diff --git a/.github/workflows/manifest.yml b/.github/workflows/manifest.yml
new file mode 100644
index 0000000..73586d1
--- /dev/null
+++ b/.github/workflows/manifest.yml
@@ -0,0 +1,95 @@
+# Simple workflow for deploying static content to GitHub Pages
+name: Deploy Installation Manifests and Versions
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+      - latest
+      - devel
+
+# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
+# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  # Single deploy job since we're just deploying
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Setup Pages
+        uses: actions/configure-pages@v3
+      - name: Setup Python
+        uses: actions/setup-python@v3.1.3
+      # Generate manifest + shields files for main branch
+      - name: Checkout main
+        id: checkout-main
+        uses: actions/checkout@v3
+        with:
+          ref: 'main'
+          clean: false
+      - name: Create outputs folders
+        if: success() || failure()
+        shell: bash
+        run: mkdir deploy; mkdir deploy/manifests; mkdir deploy/manifests/main deploy/manifests/latest deploy/manifests/devel
+      - name: Generate manifest and shields for main branch
+        id: manifest-main
+        if: ${{ (success() || failure()) && steps.checkout-main.outcome == 'success' }}
+        run: python imgen.py shields
+      - name: Save main's manifest
+        if: ${{ (success() || failure()) && steps.manifest-main.outcome == 'success' }}
+        run: mv install_manifest.json deploy/manifests/main
+      # Generate manifest for latest branch
+      - name: Checkout latest
+        id: checkout-latest
+        if: success() || failure()
+        uses: actions/checkout@v3
+        with:
+          ref: 'latest'
+          clean: false
+      - name: Generate manifest for latest
+        id: manifest-latest
+        if: ${{ (success() || failure()) && steps.checkout-latest.outcome == 'success' }}
+        run: python imgen.py
+      - name: Save latest's manifest
+        if: ${{ (success() || failure()) && steps.manifest-latest.outcome == 'success' }}
+        run: mv install_manifest.json deploy/manifests/latest
+      # Generate manifest for devel branch
+      - name: Checkout devel
+        id: checkout-devel
+        if: success() || failure()
+        uses: actions/checkout@v3
+        with:
+          ref: 'devel'
+          clean: false
+      - name: Generate manifest for devel
+        id: manifest-devel
+        if: ${{ (success() || failure()) && steps.checkout-devel.outcome == 'success' }}
+        run: python imgen.py
+      - name: Save devel's manifest
+        if: ${{ (success() || failure()) && steps.manifest-devel.outcome == 'success' }}
+        run: mv install_manifest.json deploy/manifests/devel
+      # All artifacts ready now, upload deploy directory
+      - name: Upload artifacts
+        id: upload-artifacts
+        if: ${{ (success() || failure()) && (steps.manifest-main.outcome == 'success' || steps.manifest-latest.outcome == 'success' || steps.manifest-devel.outcome == 'success') }}
+        uses: actions/upload-pages-artifact@v1
+        with:
+          # Upload manifest JSON
+          path: 'deploy/'
+      - name: Deploy to GitHub Pages
+        if: ${{ (success() || failure()) && steps.upload-artifacts.outcome == 'success' }}
+        id: deployment
+        uses: actions/deploy-pages@v2
diff --git a/.github/workflows/shields.yml b/.github/workflows/shields.yml
deleted file mode 100644
index 50698af..0000000
--- a/.github/workflows/shields.yml
+++ /dev/null
@@ -1,47 +0,0 @@
-# Simple workflow for deploying static content to GitHub Pages
-name: Deploy Component Versions
-
-on:
-  # Runs on pushes targeting the default branch
-  push:
-    branches: ["main"]
-
-  # Allows you to run this workflow manually from the Actions tab
-  workflow_dispatch:
-
-# Sets permissions of the GITHUB_TOKEN to allow deployment to GitHub Pages
-permissions:
-  contents: read
-  pages: write
-  id-token: write
-
-# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
-# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
-concurrency:
-  group: "pages"
-  cancel-in-progress: false
-
-jobs:
-  # Single deploy job since we're just deploying
-  deploy:
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-      - name: Setup Pages
-        uses: actions/configure-pages@v3
-      - name: Setup Python
-        uses: actions/setup-python@v3.1.3
-      - run: mkdir shields
-      - run: python imgen.py shields
-      - name: Upload artifact
-        uses: actions/upload-pages-artifact@v1
-        with:
-          # Upload shields JSON
-          path: 'shields/'
-      - name: Deploy to GitHub Pages
-        id: deployment
-        uses: actions/deploy-pages@v2
diff --git a/ccmsi.lua b/ccmsi.lua
index 962d5f0..a8fff8a 100644
--- a/ccmsi.lua
+++ b/ccmsi.lua
@@ -20,9 +20,10 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 local function println(message) print(tostring(message)) end
 local function print(message) term.write(tostring(message)) end
 
-local CCMSI_VERSION = "v1.0"
+local CCMSI_VERSION = "v1.2"
 
 local install_dir = "/.install-cache"
+local manifest_path = "https://mikaylafischler.github.io/cc-mek-scada/manifests/"
 local repo_path = "http://raw.githubusercontent.com/MikaylaFischler/cc-mek-scada/"
 
 local opts = { ... }
@@ -122,8 +123,8 @@ if mode == "check" then
     -- GET REMOTE MANIFEST --
     -------------------------
 
-    if opts[2] then repo_path = repo_path .. opts[2] .. "/" else repo_path = repo_path .. "main/" end
-    local install_manifest = repo_path .. "install_manifest.json"
+    if opts[2] then manifest_path = manifest_path .. opts[2] .. "/" else manifest_path = manifest_path .. "main/" end
+    local install_manifest = manifest_path .. "install_manifest.json"
 
     local response, error = http.get(install_manifest)
 
@@ -203,7 +204,8 @@ elseif mode == "install" or mode == "update" then
     -------------------------
 
     if opts[3] then repo_path = repo_path .. opts[3] .. "/" else repo_path = repo_path .. "main/" end
-    local install_manifest = repo_path .. "install_manifest.json"
+    if opts[3] then manifest_path = manifest_path .. opts[3] .. "/" else manifest_path = manifest_path .. "main/" end
+    local install_manifest = manifest_path .. "install_manifest.json"
 
     local response, error = http.get(install_manifest)
 
diff --git a/coordinator/config.lua b/coordinator/config.lua
index 3196e80..ecb7599 100644
--- a/coordinator/config.lua
+++ b/coordinator/config.lua
@@ -1,11 +1,11 @@
 local config = {}
 
--- port of the SCADA supervisor
-config.SCADA_SV_PORT = 16100
--- port to listen to incoming packets from supervisor
-config.SCADA_SV_CTL_LISTEN = 16101
--- listen port for SCADA coordinator API access
-config.SCADA_API_LISTEN = 16200
+-- supervisor comms channel
+config.SVR_CHANNEL = 16240
+-- coordinator comms channel
+config.CRD_CHANNEL = 16243
+-- pocket comms channel
+config.PKT_CHANNEL = 16244
 -- max trusted modem message distance (0 to disable check)
 config.TRUSTED_RANGE = 0
 -- time in seconds (>= 2) before assuming a remote device is no longer active
diff --git a/coordinator/coordinator.lua b/coordinator/coordinator.lua
index d7e58f7..f6e8038 100644
--- a/coordinator/coordinator.lua
+++ b/coordinator/coordinator.lua
@@ -213,14 +213,15 @@ end
 ---@nodiscard
 ---@param version string coordinator version
 ---@param modem table modem device
----@param sv_port integer port of configured supervisor
----@param sv_listen integer listening port for supervisor replys
----@param api_listen integer listening port for pocket API
+---@param crd_channel integer port of configured supervisor
+---@param svr_channel integer listening port for supervisor replys
+---@param pkt_channel integer listening port for pocket API
 ---@param range integer trusted device connection range
 ---@param sv_watchdog watchdog
-function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range, sv_watchdog)
+function coordinator.comms(version, modem, crd_channel, svr_channel, pkt_channel, range, sv_watchdog)
     local self = {
         sv_linked = false,
+        sv_addr = comms.BROADCAST,
         sv_seq_num = 0,
         sv_r_seq_num = nil,
         sv_config_err = false,
@@ -236,8 +237,7 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
     -- configure modem channels
     local function _conf_channels()
         modem.closeAll()
-        modem.open(sv_listen)
-        modem.open(api_listen)
+        modem.open(crd_channel)
     end
 
     _conf_channels()
@@ -261,23 +261,24 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
         end
 
         pkt.make(msg_type, msg)
-        s_pkt.make(self.sv_seq_num, protocol, pkt.raw_sendable())
+        s_pkt.make(self.sv_addr, self.sv_seq_num, protocol, pkt.raw_sendable())
 
-        modem.transmit(sv_port, sv_listen, s_pkt.raw_sendable())
+        modem.transmit(svr_channel, crd_channel, s_pkt.raw_sendable())
         self.sv_seq_num = self.sv_seq_num + 1
     end
 
     -- send an API establish request response
-    ---@param dest integer
-    ---@param msg table
-    local function _send_api_establish_ack(seq_id, dest, msg)
+    ---@param packet scada_packet
+    ---@param ack ESTABLISH_ACK
+    local function _send_api_establish_ack(packet, ack)
         local s_pkt = comms.scada_packet()
         local m_pkt = comms.mgmt_packet()
 
-        m_pkt.make(SCADA_MGMT_TYPE.ESTABLISH, msg)
-        s_pkt.make(seq_id, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        m_pkt.make(SCADA_MGMT_TYPE.ESTABLISH, { ack })
+        s_pkt.make(packet.src_addr(), packet.seq_num() + 1, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
-        modem.transmit(dest, api_listen, s_pkt.raw_sendable())
+        modem.transmit(pkt_channel, crd_channel, s_pkt.raw_sendable())
+        self.last_api_est_acks[packet.src_addr()] = ack
     end
 
     -- attempt connection establishment
@@ -307,7 +308,9 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
     -- close the connection to the server
     function public.close()
         sv_watchdog.cancel()
+        self.sv_addr = comms.BROADCAST
         self.sv_linked = false
+        self.sv_r_seq_num = nil
         _send_sv(PROTOCOL.SCADA_MGMT, SCADA_MGMT_TYPE.CLOSE, {})
     end
 
@@ -335,12 +338,13 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                 tick_dmesg_waiting(math.max(0, timeout_s - (util.time_s() - start)))
                 _send_establish()
                 clock.start()
+            elseif event == "timer" then
+                -- keep checking watchdog timers
+                apisessions.check_all_watchdogs(p1)
             elseif event == "modem_message" then
                 -- handle message
                 local packet = public.parse_packet(p1, p2, p3, p4, p5)
-                if packet ~= nil and packet.type == SCADA_MGMT_TYPE.ESTABLISH then
-                    public.handle_packet(packet)
-                end
+                public.handle_packet(packet)
             elseif event == "terminate" then
                 terminated = true
                 break
@@ -435,15 +439,18 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
     ---@param packet mgmt_frame|crdn_frame|capi_frame|nil
     function public.handle_packet(packet)
         if packet ~= nil then
-            local l_port = packet.scada_frame.local_port()
-            local r_port = packet.scada_frame.remote_port()
+            local l_chan = packet.scada_frame.local_channel()
+            local r_chan = packet.scada_frame.remote_channel()
+            local src_addr = packet.scada_frame.src_addr()
             local protocol = packet.scada_frame.protocol()
 
-            if l_port == api_listen then
+            if l_chan ~= crd_channel then
+                log.debug("received packet on unconfigured channel " .. l_chan, true)
+            elseif r_chan == pkt_channel then
                 if protocol == PROTOCOL.COORD_API then
                     ---@cast packet capi_frame
                     -- look for an associated session
-                    local session = apisessions.find_session(r_port)
+                    local session = apisessions.find_session(src_addr)
 
                     -- API packet
                     if session ~= nil then
@@ -456,7 +463,7 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                 elseif protocol == PROTOCOL.SCADA_MGMT then
                     ---@cast packet mgmt_frame
                     -- look for an associated session
-                    local session = apisessions.find_session(r_port)
+                    local session = apisessions.find_session(src_addr)
 
                     -- SCADA management packet
                     if session ~= nil then
@@ -464,8 +471,6 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                         session.in_queue.push_packet(packet)
                     elseif packet.type == SCADA_MGMT_TYPE.ESTABLISH then
                         -- establish a new session
-                        local next_seq_id = packet.scada_frame.seq_num() + 1
-
                         -- validate packet and continue
                         if packet.length == 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
                             local comms_v = packet.data[1]
@@ -473,42 +478,43 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                             local dev_type = packet.data[3]
 
                             if comms_v ~= comms.version then
-                                if self.last_api_est_acks[r_port] ~= ESTABLISH_ACK.BAD_VERSION then
+                                if self.last_api_est_acks[src_addr] ~= ESTABLISH_ACK.BAD_VERSION then
                                     log.info(util.c("dropping API establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                                    self.last_api_est_acks[r_port] = ESTABLISH_ACK.BAD_VERSION
                                 end
 
-                                _send_api_establish_ack(next_seq_id, r_port, { ESTABLISH_ACK.BAD_VERSION })
+                                _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
                             elseif dev_type == DEVICE_TYPE.PKT then
                                 -- pocket linking request
-                                local id = apisessions.establish_session(l_port, r_port, firmware_v)
-                                println(util.c("API: pocket (", firmware_v, ") [:", r_port, "] connected with session ID ", id))
-                                coordinator.log_comms(util.c("API: pocket (", firmware_v, ") [:", r_port, "] connected with session ID ", id))
+                                local id = apisessions.establish_session(src_addr, firmware_v)
+                                println(util.c("[API] pocket (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+                                coordinator.log_comms(util.c("API_ESTABLISH: pocket (", firmware_v, ") [@", src_addr, "] connected with session ID ", id))
 
-                                _send_api_establish_ack(next_seq_id, r_port, { ESTABLISH_ACK.ALLOW })
-                                self.last_api_est_acks[r_port] = ESTABLISH_ACK.ALLOW
+                                _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.ALLOW)
                             else
-                                log.debug(util.c("illegal establish packet for device ", dev_type, " on API listening channel"))
-                                _send_api_establish_ack(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                                log.debug(util.c("API_ESTABLISH: illegal establish packet for device ", dev_type, " on pocket channel"))
+                                _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.DENY)
                             end
                         else
                             log.debug("invalid establish packet (on API listening channel)")
-                            _send_api_establish_ack(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                            _send_api_establish_ack(packet.scada_frame, ESTABLISH_ACK.DENY)
                         end
                     else
                         -- any other packet should be session related, discard it
-                        log.debug(util.c(r_port, "->", l_port, ": discarding SCADA_MGMT packet without a known session"))
+                        log.debug(util.c("discarding pocket SCADA_MGMT packet without a known session from computer ", src_addr))
                     end
                 else
-                    log.debug("illegal packet type " .. protocol .. " on api listening channel", true)
+                    log.debug("illegal packet type " .. protocol .. " on pocket channel", true)
                 end
-            elseif l_port == sv_listen then
+            elseif r_chan == svr_channel then
                 -- check sequence number
                 if self.sv_r_seq_num == nil then
                     self.sv_r_seq_num = packet.scada_frame.seq_num()
                 elseif self.connected and ((self.sv_r_seq_num + 1) ~= packet.scada_frame.seq_num()) then
                     log.warning("sequence out-of-order: last = " .. self.sv_r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
                     return
+                elseif self.sv_linked and src_addr ~= self.sv_addr then
+                    log.debug("received packet from unknown computer " .. src_addr .. " while linked; channel in use by another system?")
+                    return
                 else
                     self.sv_r_seq_num = packet.scada_frame.seq_num()
                 end
@@ -659,6 +665,7 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                                         -- init io controller
                                         iocontrol.init(conf, public)
 
+                                        self.sv_addr = src_addr
                                         self.sv_linked = true
                                         self.sv_config_err = false
                                     else
@@ -704,10 +711,10 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                                 local trip_time = util.time() - timestamp
 
                                 if trip_time > 750 then
-                                    log.warning("coord KEEP_ALIVE trip time > 750ms (" .. trip_time .. "ms)")
+                                    log.warning("coordinator KEEP_ALIVE trip time > 750ms (" .. trip_time .. "ms)")
                                 end
 
-                                -- log.debug("coord RTT = " .. trip_time .. "ms")
+                                -- log.debug("coordinator RTT = " .. trip_time .. "ms")
 
                                 iocontrol.get_db().facility.ps.publish("sv_ping", trip_time)
 
@@ -718,7 +725,9 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                         elseif packet.type == SCADA_MGMT_TYPE.CLOSE then
                             -- handle session close
                             sv_watchdog.cancel()
+                            self.sv_addr = comms.BROADCAST
                             self.sv_linked = false
+                            self.sv_r_seq_num = nil
                             println_ts("server connection closed by remote host")
                             log.info("server connection closed by remote host")
                         else
@@ -731,7 +740,7 @@ function coordinator.comms(version, modem, sv_port, sv_listen, api_listen, range
                     log.debug("illegal packet type " .. protocol .. " on supervisor listening channel", true)
                 end
             else
-                log.debug("received packet on unconfigured channel " .. l_port, true)
+                log.debug("received packet for unknown channel " .. r_chan, true)
             end
         end
     end
diff --git a/coordinator/session/apisessions.lua b/coordinator/session/apisessions.lua
index c6d5a20..17988f5 100644
--- a/coordinator/session/apisessions.lua
+++ b/coordinator/session/apisessions.lua
@@ -5,7 +5,7 @@ local util   = require("scada-common.util")
 
 local config = require("coordinator.config")
 
-local api    = require("coordinator.session.api")
+local pocket = require("coordinator.session.pocket")
 
 local apisessions = {}
 
@@ -18,7 +18,7 @@ local self = {
 -- PRIVATE FUNCTIONS --
 
 -- handle a session output queue
----@param session api_session_struct
+---@param session pkt_session_struct
 local function _api_handle_outq(session)
     -- record handler start time
     local handle_start = util.time()
@@ -31,7 +31,7 @@ local function _api_handle_outq(session)
         if msg ~= nil then
             if msg.qtype == mqueue.TYPE.PACKET then
                 -- handle a packet to be sent
-                self.modem.transmit(session.r_port, session.l_port, msg.message.raw_sendable())
+                self.modem.transmit(config.PKT_CHANNEL, config.CRD_CHANNEL, msg.message.raw_sendable())
             elseif msg.qtype == mqueue.TYPE.COMMAND then
                 -- handle instruction/notification
             elseif msg.qtype == mqueue.TYPE.DATA then
@@ -41,15 +41,15 @@ local function _api_handle_outq(session)
 
         -- max 100ms spent processing queue
         if util.time() - handle_start > 100 then
-            log.warning("API out queue handler exceeded 100ms queue process limit")
-            log.warning(util.c("offending session: port ", session.r_port))
+            log.warning("[API] out queue handler exceeded 100ms queue process limit")
+            log.warning(util.c("[API] offending session: ", session))
             break
         end
     end
 end
 
 -- cleanly close a session
----@param session api_session_struct
+---@param session pkt_session_struct
 local function _shutdown(session)
     session.open = false
     session.instance.close()
@@ -58,11 +58,11 @@ local function _shutdown(session)
     while session.out_queue.ready() do
         local msg = session.out_queue.pop()
         if msg ~= nil and msg.qtype == mqueue.TYPE.PACKET then
-            self.modem.transmit(session.r_port, session.l_port, msg.message.raw_sendable())
+            self.modem.transmit(config.PKT_CHANNEL, config.CRD_CHANNEL, msg.message.raw_sendable())
         end
     end
 
-    log.debug(util.c("closed API session ", session.instance.get_id(), " on remote port ", session.r_port))
+    log.debug(util.c("[API] closed session ", session))
 end
 
 -- PUBLIC FUNCTIONS --
@@ -81,54 +81,60 @@ end
 
 -- find a session by remote port
 ---@nodiscard
----@param port integer
----@return api_session_struct|nil
-function apisessions.find_session(port)
+---@param source_addr integer
+---@return pkt_session_struct|nil
+function apisessions.find_session(source_addr)
     for i = 1, #self.sessions do
-        if self.sessions[i].r_port == port then return self.sessions[i] end
+        if self.sessions[i].s_addr == source_addr then return self.sessions[i] end
     end
     return nil
 end
 
 -- establish a new API session
 ---@nodiscard
----@param local_port integer
----@param remote_port integer
+---@param source_addr integer
 ---@param version string
 ---@return integer session_id
-function apisessions.establish_session(local_port, remote_port, version)
-    ---@class api_session_struct
-    local api_s = {
+function apisessions.establish_session(source_addr, version)
+    ---@class pkt_session_struct
+    local pkt_s = {
         open = true,
         version = version,
-        l_port = local_port,
-        r_port = remote_port,
+        s_addr = source_addr,
         in_queue = mqueue.new(),
         out_queue = mqueue.new(),
-        instance = nil  ---@type api_session
+        instance = nil  ---@type pkt_session
     }
 
-    api_s.instance = api.new_session(self.next_id, api_s.in_queue, api_s.out_queue, config.API_TIMEOUT)
-    table.insert(self.sessions, api_s)
+    local id = self.next_id
 
-    log.debug(util.c("established new API session to ", remote_port, " with ID ", self.next_id))
+    pkt_s.instance = pocket.new_session(id, source_addr, pkt_s.in_queue, pkt_s.out_queue, config.API_TIMEOUT)
+    table.insert(self.sessions, pkt_s)
 
-    self.next_id = self.next_id + 1
+    local mt = {
+        ---@param s pkt_session_struct
+        __tostring = function (s)  return util.c("PKT [", id, "] (@", s.s_addr, ")") end
+    }
+
+    setmetatable(pkt_s, mt)
+
+    log.debug(util.c("[API] established new session: ", pkt_s))
+
+    self.next_id = id + 1
 
     -- success
-    return api_s.instance.get_id()
+    return pkt_s.instance.get_id()
 end
 
 -- attempt to identify which session's watchdog timer fired
 ---@param timer_event number
 function apisessions.check_all_watchdogs(timer_event)
     for i = 1, #self.sessions do
-        local session = self.sessions[i]  ---@type api_session_struct
+        local session = self.sessions[i]  ---@type pkt_session_struct
         if session.open then
             local triggered = session.instance.check_wd(timer_event)
             if triggered then
-                log.debug(util.c("watchdog closing API session ", session.instance.get_id(),
-                    " on remote port ", session.r_port, "..."))
+                log.debug(util.c("[API] watchdog closing session ", session, "..."))
                 _shutdown(session)
             end
         end
@@ -138,7 +144,7 @@ end
 -- iterate all the API sessions
 function apisessions.iterate_all()
     for i = 1, #self.sessions do
-        local session = self.sessions[i]    ---@type api_session_struct
+        local session = self.sessions[i]    ---@type pkt_session_struct
 
         if session.open and session.instance.iterate() then
             _api_handle_outq(session)
@@ -152,10 +158,9 @@ end
 function apisessions.free_all_closed()
     local f = function (session) return session.open end
 
-    ---@param session api_session_struct
+    ---@param session pkt_session_struct
     local on_delete = function (session)
-        log.debug(util.c("free'ing closed API session ", session.instance.get_id(),
-            " on remote port ", session.r_port))
+        log.debug(util.c("[API] free'ing closed session ", session))
     end
 
     util.filter_table(self.sessions, f, on_delete)
@@ -164,7 +169,7 @@ end
 -- close all open connections
 function apisessions.close_all()
     for i = 1, #self.sessions do
-        local session = self.sessions[i]  ---@type api_session_struct
+        local session = self.sessions[i]  ---@type pkt_session_struct
         if session.open then _shutdown(session) end
     end
 
diff --git a/coordinator/session/api.lua b/coordinator/session/pocket.lua
similarity index 89%
rename from coordinator/session/api.lua
rename to coordinator/session/pocket.lua
index 8f21483..ddabdda 100644
--- a/coordinator/session/api.lua
+++ b/coordinator/session/pocket.lua
@@ -3,7 +3,7 @@ local log    = require("scada-common.log")
 local mqueue = require("scada-common.mqueue")
 local util   = require("scada-common.util")
 
-local api = {}
+local pocket = {}
 
 local PROTOCOL = comms.PROTOCOL
 -- local CAPI_TYPE = comms.CAPI_TYPE
@@ -21,8 +21,8 @@ local API_S_CMDS = {
 local API_S_DATA = {
 }
 
-api.API_S_CMDS = API_S_CMDS
-api.API_S_DATA = API_S_DATA
+pocket.API_S_CMDS = API_S_CMDS
+pocket.API_S_DATA = API_S_DATA
 
 local PERIODICS = {
     KEEP_ALIVE = 2000
@@ -31,11 +31,12 @@ local PERIODICS = {
 -- pocket API session
 ---@nodiscard
 ---@param id integer session ID
+---@param s_addr integer device source address
 ---@param in_queue mqueue in message queue
 ---@param out_queue mqueue out message queue
 ---@param timeout number communications timeout
-function api.new_session(id, in_queue, out_queue, timeout)
-    local log_header = "api_session(" .. id .. "): "
+function pocket.new_session(id, s_addr, in_queue, out_queue, timeout)
+    local log_header = "pkt_session(" .. id .. "): "
 
     local self = {
         -- connection properties
@@ -61,10 +62,10 @@ function api.new_session(id, in_queue, out_queue, timeout)
         }
     }
 
-    ---@class api_session
+    ---@class pkt_session
     local public = {}
 
-    -- mark this API session as closed, stop watchdog
+    -- mark this pocket session as closed, stop watchdog
     local function _close()
         self.conn_watchdog.cancel()
         self.connected = false
@@ -92,7 +93,7 @@ function api.new_session(id, in_queue, out_queue, timeout)
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -117,8 +118,6 @@ function api.new_session(id, in_queue, out_queue, timeout)
         -- process packet
         if pkt.scada_frame.protocol() == PROTOCOL.COORD_API then
             ---@cast pkt capi_frame
-            -- feed watchdog
-            self.conn_watchdog.feed()
 
             -- handle packet by type
             if pkt.type == nil then
@@ -136,11 +135,11 @@ function api.new_session(id, in_queue, out_queue, timeout)
                     self.last_rtt = srv_now - srv_start
 
                     if self.last_rtt > 750 then
-                        log.warning(log_header .. "API KEEP_ALIVE round trip time > 750ms (" .. self.last_rtt .. "ms)")
+                        log.warning(log_header .. "PKT KEEP_ALIVE round trip time > 750ms (" .. self.last_rtt .. "ms)")
                     end
 
-                    -- log.debug(log_header .. "API RTT = " .. self.last_rtt .. "ms")
-                    -- log.debug(log_header .. "API TT  = " .. (srv_now - api_send) .. "ms")
+                    -- log.debug(log_header .. "PKT RTT = " .. self.last_rtt .. "ms")
+                    -- log.debug(log_header .. "PKT TT  = " .. (srv_now - api_send) .. "ms")
                 else
                     log.debug(log_header .. "SCADA keep alive packet length mismatch")
                 end
@@ -173,7 +172,7 @@ function api.new_session(id, in_queue, out_queue, timeout)
     function public.close()
         _close()
         _send_mgmt(SCADA_MGMT_TYPE.CLOSE, {})
-        println("connection to API session " .. id .. " closed by server")
+        println("connection to pocket session " .. id .. " closed by server")
         log.info(log_header .. "session closed by server")
     end
 
@@ -212,7 +211,7 @@ function api.new_session(id, in_queue, out_queue, timeout)
 
             -- exit if connection was closed
             if not self.connected then
-                println("connection to API session " .. id .. " closed by remote host")
+                println("connection to pocket session " .. id .. " closed by remote host")
                 log.info(log_header .. "session closed by remote host")
                 return self.connected
             end
@@ -248,4 +247,4 @@ function api.new_session(id, in_queue, out_queue, timeout)
     return public
 end
 
-return api
+return pocket
diff --git a/coordinator/startup.lua b/coordinator/startup.lua
index 367c1ca..5d4fec8 100644
--- a/coordinator/startup.lua
+++ b/coordinator/startup.lua
@@ -4,23 +4,23 @@
 
 require("/initenv").init_env()
 
-local crash        = require("scada-common.crash")
-local log          = require("scada-common.log")
-local ppm          = require("scada-common.ppm")
-local tcallbackdsp = require("scada-common.tcallbackdsp")
-local util         = require("scada-common.util")
+local crash       = require("scada-common.crash")
+local log         = require("scada-common.log")
+local ppm         = require("scada-common.ppm")
+local tcd         = require("scada-common.tcd")
+local util        = require("scada-common.util")
 
-local core         = require("graphics.core")
+local core        = require("graphics.core")
 
-local config       = require("coordinator.config")
-local coordinator  = require("coordinator.coordinator")
-local iocontrol    = require("coordinator.iocontrol")
-local renderer     = require("coordinator.renderer")
-local sounder      = require("coordinator.sounder")
+local config      = require("coordinator.config")
+local coordinator = require("coordinator.coordinator")
+local iocontrol   = require("coordinator.iocontrol")
+local renderer    = require("coordinator.renderer")
+local sounder     = require("coordinator.sounder")
 
-local apisessions  = require("coordinator.session.apisessions")
+local apisessions = require("coordinator.session.apisessions")
 
-local COORDINATOR_VERSION = "v0.15.2"
+local COORDINATOR_VERSION = "v0.16.0"
 
 local println = util.println
 local println_ts = util.println_ts
@@ -37,9 +37,9 @@ local log_comms_connecting = coordinator.log_comms_connecting
 
 local cfv = util.new_validator()
 
-cfv.assert_port(config.SCADA_SV_PORT)
-cfv.assert_port(config.SCADA_SV_CTL_LISTEN)
-cfv.assert_port(config.SCADA_API_LISTEN)
+cfv.assert_channel(config.SVR_CHANNEL)
+cfv.assert_channel(config.CRD_CHANNEL)
+cfv.assert_channel(config.PKT_CHANNEL)
 cfv.assert_type_int(config.TRUSTED_RANGE)
 cfv.assert_type_num(config.SV_TIMEOUT)
 cfv.assert_min(config.SV_TIMEOUT, 2)
@@ -148,8 +148,8 @@ local function main()
     log.debug("startup> conn watchdog created")
 
     -- start comms, open all channels
-    local coord_comms = coordinator.comms(COORDINATOR_VERSION, modem, config.SCADA_SV_PORT, config.SCADA_SV_CTL_LISTEN,
-                                            config.SCADA_API_LISTEN, config.TRUSTED_RANGE, conn_watchdog)
+    local coord_comms = coordinator.comms(COORDINATOR_VERSION, modem, config.CRD_CHANNEL, config.SVR_CHANNEL,
+                                            config.PKT_CHANNEL, config.TRUSTED_RANGE, conn_watchdog)
     log.debug("startup> comms init")
     log_comms("comms initialized")
 
@@ -163,7 +163,7 @@ local function main()
 
     -- attempt to connect to the supervisor or exit
     local function init_connect_sv()
-        local tick_waiting, task_done = log_comms_connecting("attempting to connect to configured supervisor on channel " .. config.SCADA_SV_PORT)
+        local tick_waiting, task_done = log_comms_connecting("attempting to connect to configured supervisor on channel " .. config.SVR_CHANNEL)
 
         -- attempt to establish a connection with the supervisory computer
         if not coord_comms.sv_connect(60, tick_waiting, task_done) then
@@ -334,7 +334,7 @@ local function main()
                 apisessions.check_all_watchdogs(param1)
 
                 -- notify timer callback dispatcher
-                tcallbackdsp.handle(param1)
+                tcd.handle(param1)
             end
         elseif event == "modem_message" then
             -- got a packet
diff --git a/coordinator/ui/components/processctl.lua b/coordinator/ui/components/processctl.lua
index a238a8c..eaeb8ab 100644
--- a/coordinator/ui/components/processctl.lua
+++ b/coordinator/ui/components/processctl.lua
@@ -1,4 +1,4 @@
-local tcd               = require("scada-common.tcallbackdsp")
+local tcd               = require("scada-common.tcd")
 local util              = require("scada-common.util")
 
 local iocontrol         = require("coordinator.iocontrol")
@@ -33,7 +33,7 @@ local period = core.flasher.PERIOD
 ---@param x integer top left x
 ---@param y integer top left y
 local function new_view(root, x, y)
-    assert(root.height() >= (y + 24), "main display not of sufficient vertical resolution (add an additional row of monitors)")
+    assert(root.get_height() >= (y + 24), "main display not of sufficient vertical resolution (add an additional row of monitors)")
 
     local facility = iocontrol.get_db().facility
     local units = iocontrol.get_db().units
diff --git a/coordinator/ui/components/unit_overview.lua b/coordinator/ui/components/unit_overview.lua
index bd341bf..3af8c83 100644
--- a/coordinator/ui/components/unit_overview.lua
+++ b/coordinator/ui/components/unit_overview.lua
@@ -38,7 +38,7 @@ local function make(parent, x, y, unit)
         height = 17
     end
 
-    assert(parent.height() >= (y + height), "main display not of sufficient vertical resolution (add an additional row of monitors)")
+    assert(parent.get_height() >= (y + height), "main display not of sufficient vertical resolution (add an additional row of monitors)")
 
     -- bounding box div
     local root = Div{parent=parent,x=x,y=y,width=80,height=height}
diff --git a/coordinator/ui/layout/main_view.lua b/coordinator/ui/layout/main_view.lua
index a758b24..a7b3c86 100644
--- a/coordinator/ui/layout/main_view.lua
+++ b/coordinator/ui/layout/main_view.lua
@@ -32,7 +32,7 @@ local function init(main)
     local header = TextBox{parent=main,y=1,text="Nuclear Generation Facility SCADA Coordinator",alignment=TEXT_ALIGN.CENTER,height=1,fg_bg=style.header}
     local ping = DataIndicator{parent=main,x=1,y=1,label="SVTT",format="%d",value=0,unit="ms",lu_colors=cpair(colors.lightGray, colors.white),width=12,fg_bg=style.header}
     -- max length example: "01:23:45 AM - Wednesday, September 28 2022"
-    local datetime = TextBox{parent=main,x=(header.width()-42),y=1,text="",alignment=TEXT_ALIGN.RIGHT,width=42,height=1,fg_bg=style.header}
+    local datetime = TextBox{parent=main,x=(header.get_width()-42),y=1,text="",alignment=TEXT_ALIGN.RIGHT,width=42,height=1,fg_bg=style.header}
 
     ping.register(facility.ps, "sv_ping", ping.update)
     datetime.register(facility.ps, "date_time", datetime.set_value)
@@ -45,12 +45,12 @@ local function init(main)
     -- unit overviews
     if facility.num_units >= 1 then
         uo_1 = unit_overview(main, 2, 3, units[1])
-        row_1_height = uo_1.height()
+        row_1_height = uo_1.get_height()
     end
 
     if facility.num_units >= 2 then
         uo_2 = unit_overview(main, 84, 3, units[2])
-        row_1_height = math.max(row_1_height, uo_2.height())
+        row_1_height = math.max(row_1_height, uo_2.get_height())
     end
 
     cnc_y_start = cnc_y_start + row_1_height + 1
@@ -60,11 +60,11 @@ local function init(main)
         local row_2_offset = cnc_y_start
 
         uo_3 = unit_overview(main, 2, row_2_offset, units[3])
-        cnc_y_start = row_2_offset + uo_3.height() + 1
+        cnc_y_start = row_2_offset + uo_3.get_height() + 1
 
         if facility.num_units == 4 then
             uo_4 = unit_overview(main, 84, row_2_offset, units[4])
-            cnc_y_start = math.max(cnc_y_start, row_2_offset + uo_4.height() + 1)
+            cnc_y_start = math.max(cnc_y_start, row_2_offset + uo_4.get_height() + 1)
         end
     end
 
@@ -73,11 +73,11 @@ local function init(main)
     cnc_y_start = cnc_y_start
 
     -- induction matrix and process control interfaces are 24 tall + space needed for divider
-    local cnc_bottom_align_start = main.height() - 26
+    local cnc_bottom_align_start = main.get_height() - 26
 
     assert(cnc_bottom_align_start >= cnc_y_start, "main display not of sufficient vertical resolution (add an additional row of monitors)")
 
-    TextBox{parent=main,y=cnc_bottom_align_start,text=util.strrep("\x8c", header.width()),alignment=TEXT_ALIGN.CENTER,height=1,fg_bg=cpair(colors.lightGray,colors.gray)}
+    TextBox{parent=main,y=cnc_bottom_align_start,text=util.strrep("\x8c", header.get_width()),alignment=TEXT_ALIGN.CENTER,height=1,fg_bg=cpair(colors.lightGray,colors.gray)}
 
     cnc_bottom_align_start = cnc_bottom_align_start + 2
 
diff --git a/graphics/element.lua b/graphics/element.lua
index b865af0..ae2daee 100644
--- a/graphics/element.lua
+++ b/graphics/element.lua
@@ -12,12 +12,11 @@ local element = {}
 ---@field id? string element id
 ---@field x? integer 1 if omitted
 ---@field y? integer next line if omitted
----@field offset_x? integer 0 if omitted
----@field offset_y? integer 0 if omitted
 ---@field width? integer parent width if omitted
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 ---@alias graphics_args graphics_args_generic
 ---|waiting_args
@@ -46,6 +45,7 @@ local element = {}
 ---|colormap_args
 ---|displaybox_args
 ---|div_args
+---|listbox_args
 ---|multipane_args
 ---|pipenet_args
 ---|rectangle_args
@@ -62,26 +62,26 @@ local element = {}
 ---@param args graphics_args arguments
 function element.new(args)
     local self = {
-        id = -1,
+        id = nil,                                       ---@type element_id|nil
         elem_type = debug.getinfo(2).name,
         define_completed = false,
         p_window = nil,                                 ---@type table
         position = { x = 1, y = 1 },                    ---@type coordinate_2d
-        child_offset = { x = 0, y = 0 },
         bounds = { x1 = 1, y1 = 1, x2 = 1, y2 = 1 },    ---@class element_bounds
         next_y = 1,
-        children = {},
         subscriptions = {},
         mt = {}
     }
 
-    ---@class graphics_template
+    ---@class graphics_base
     local protected = {
         enabled = true,
-        value = nil,    ---@type any
-        window = nil,   ---@type table
+        value = nil,            ---@type any
+        window = nil,           ---@type table
+        content_window = nil,   ---@type table|nil
         fg_bg = core.cpair(colors.white, colors.black),
-        frame = core.gframe(1, 1, 1, 1)
+        frame = core.gframe(1, 1, 1, 1),
+        children = {}
     }
 
     local name_brief = "graphics.element{" .. self.elem_type .. "}: "
@@ -101,10 +101,8 @@ function element.new(args)
     -------------------------
 
     -- prepare the template
-    ---@param offset_x integer x offset
-    ---@param offset_y integer y offset
     ---@param next_y integer next line if no y was provided
-    function protected.prepare_template(offset_x, offset_y, next_y)
+    function protected.prepare_template(next_y)
         -- get frame coordinates/size
         if args.gframe ~= nil then
             protected.frame.x = args.gframe.x
@@ -114,36 +112,18 @@ function element.new(args)
         else
             local w, h = self.p_window.getSize()
             protected.frame.x = args.x or 1
-
-            if args.parent ~= nil then
-                protected.frame.y = args.y or (next_y - offset_y)
-            else
-                protected.frame.y = args.y or next_y
-            end
-
+            protected.frame.y = args.y or next_y
             protected.frame.w = args.width or w
             protected.frame.h = args.height or h
         end
 
-        -- inner offsets
-        if args.offset_x ~= nil then self.child_offset.x = args.offset_x end
-        if args.offset_y ~= nil then self.child_offset.y = args.offset_y end
-
         -- adjust window frame if applicable
         local f = protected.frame
-        local x = f.x
-        local y = f.y
-
-        -- apply offsets
         if args.parent ~= nil then
             -- constrain to parent inner width/height
             local w, h = self.p_window.getSize()
-            f.w = math.min(f.w, w - ((2 * offset_x) + (f.x - 1)))
-            f.h = math.min(f.h, h - ((2 * offset_y) + (f.y - 1)))
-
-            -- offset x/y
-            f.x = x + offset_x
-            f.y = y + offset_y
+            f.w = math.min(f.w, w - (f.x - 1))
+            f.h = math.min(f.h, h - (f.y - 1))
         end
 
         -- check frame
@@ -153,7 +133,7 @@ function element.new(args)
         assert(f.h >= 1, name_brief .. "frame height not >= 1")
 
         -- create window
-        protected.window = window.create(self.p_window, f.x, f.y, f.w, f.h, true)
+        protected.window = window.create(self.p_window, f.x, f.y, f.w, f.h, args.hidden ~= true)
 
         -- init colors
         if args.fg_bg ~= nil then
@@ -198,15 +178,15 @@ function element.new(args)
 -- luacheck: push ignore
 ---@diagnostic disable: unused-local, unused-vararg
 
-    -- dynamically insert a child element
-    ---@param id string|integer element identifier
-    ---@param elem graphics_element element
-    function protected.insert(id, elem)
+    -- handle a child element having been added
+    ---@param id element_id element identifier
+    ---@param child graphics_element child element
+    function protected.on_added(id, child)
     end
 
-    -- dynamically remove a child element
-    ---@param id string|integer element identifier
-    function protected.remove(id)
+    -- handle a child element having been removed
+    ---@param id element_id element identifier
+    function protected.on_removed(id)
     end
 
     -- handle a mouse event
@@ -279,6 +259,14 @@ function element.new(args)
     ---@return graphics_element element, element_id id
     function protected.get() return public, self.id end
 
+    -- report completion of element instantiation and get the public interface
+    ---@nodiscard
+    ---@return graphics_element element, element_id id
+    function protected.complete()
+        if args.parent ~= nil then args.parent.__child_ready(self.id, public) end
+        return public, self.id
+    end
+
     -----------
     -- SETUP --
     -----------
@@ -294,7 +282,8 @@ function element.new(args)
 
     -- prepare the template
     if args.parent == nil then
-        protected.prepare_template(0, 0, 1)
+        self.id = args.id or "__ROOT__"
+        protected.prepare_template(1)
     else
         self.id = args.parent.__add_child(args.id, protected)
     end
@@ -305,11 +294,21 @@ function element.new(args)
 
     -- get the window object
     ---@nodiscard
-    function public.window() return protected.window end
+    function public.window() return protected.content_window or protected.window end
 
     -- delete this element (hide and unsubscribe from PSIL)
     function public.delete()
-        -- hide + stop animations
+        local fg_bg = protected.fg_bg
+
+        if args.parent ~= nil then
+            -- grab parent fg/bg so we can clear cleanly as a child element
+            fg_bg = args.parent.get_fg_bg()
+        end
+
+        -- clear, hide, and stop animations
+        protected.window.setBackgroundColor(fg_bg.bkg)
+        protected.window.setTextColor(fg_bg.fgd)
+        protected.window.clear()
         public.hide()
 
         -- unsubscribe from PSIL
@@ -319,9 +318,14 @@ function element.new(args)
         end
 
         -- delete all children
-        for k, v in pairs(self.children) do
+        for k, v in pairs(protected.children) do
             v.delete()
-            self.children[k] = nil
+            protected.children[k] = nil
+        end
+
+        if args.parent ~= nil then
+            -- remove self from parent
+            args.parent.__remove_child(self.id)
         end
     end
 
@@ -330,41 +334,53 @@ function element.new(args)
     -- add a child element
     ---@nodiscard
     ---@param key string|nil id
-    ---@param child graphics_template
+    ---@param child graphics_base
     ---@return integer|string key
     function public.__add_child(key, child)
-        -- offset first automatic placement
-        if self.next_y <= self.child_offset.y then
-            self.next_y = self.child_offset.y + 1
-        end
-
-        child.prepare_template(self.child_offset.x, self.child_offset.y, self.next_y)
+        child.prepare_template(self.next_y)
 
         self.next_y = child.frame.y + child.frame.h
 
         local child_element = child.get()
 
         if key == nil then
-            table.insert(self.children, child_element)
-            return #self.children
+            table.insert(protected.children, child_element)
+            return #protected.children
         else
-            self.children[key] = child_element
+            protected.children[key] = child_element
             return key
         end
     end
 
+    -- remove a child element
+    ---@param key element_id id
+    function public.__remove_child(key)
+        if protected.children[key] ~= nil then
+            protected.on_removed(key)
+            protected.children[key] = nil
+        end
+    end
+
+    -- actions to take upon a child element becoming ready (initial draw/construction completed)
+    ---@param key element_id id
+    ---@param child graphics_element
+    function public.__child_ready(key, child)
+        protected.on_added(key, child)
+    end
+
     -- get a child element
     ---@nodiscard
     ---@param id element_id
     ---@return graphics_element
-    function public.get_child(id) return self.children[id] end
+    function public.get_child(id) return protected.children[id] end
 
     -- remove a child element
     ---@param id element_id
     function public.remove(id)
-        if self.children[id] ~= nil then
-            self.children[id].delete()
-            self.children[id] = nil
+        if protected.children[id] ~= nil then
+            protected.children[id].delete()
+            protected.on_removed(id)
+            protected.children[id] = nil
         end
     end
 
@@ -373,37 +389,18 @@ function element.new(args)
     ---@param id element_id
     ---@return graphics_element|nil element
     function public.get_element_by_id(id)
-        if self.children[id] == nil then
-            for _, child in pairs(self.children) do
+        if protected.children[id] == nil then
+            for _, child in pairs(protected.children) do
                 local elem = child.get_element_by_id(id)
                 if elem ~= nil then return elem end
             end
         else
-            return self.children[id]
+            return protected.children[id]
         end
 
         return nil
     end
 
-    -- DYNAMIC CHILD ELEMENTS --
-
-    -- insert an element as a contained child<br>
-    -- this is intended to be used dynamically, and depends on the target element type.<br>
-    -- not all elements support dynamic children.
-    ---@param id string|integer element identifier
-    ---@param elem graphics_element element
-    function public.insert_element(id, elem)
-        protected.insert(id, elem)
-    end
-
-    -- remove an element from contained children<br>
-    -- this is intended to be used dynamically, and depends on the target element type.<br>
-    -- not all elements support dynamic children.
-    ---@param id string|integer element identifier
-    function public.remove_element(id)
-        protected.remove(id)
-    end
-
     -- AUTO-PLACEMENT --
 
     -- skip a line for automatically placed elements
@@ -437,14 +434,14 @@ function element.new(args)
     -- get element width
     ---@nodiscard
     ---@return integer width
-    function public.width()
+    function public.get_width()
         return protected.frame.w
     end
 
     -- get element height
     ---@nodiscard
     ---@return integer height
-    function public.height()
+    function public.get_height()
         return protected.frame.h
     end
 
@@ -519,7 +516,7 @@ function element.new(args)
 
             -- handle the mouse event then pass to children
             protected.handle_mouse(event_T)
-            for _, child in pairs(self.children) do child.handle_mouse(event_T) end
+            for _, child in pairs(protected.children) do child.handle_mouse(event_T) end
         end
     end
 
@@ -545,27 +542,61 @@ function element.new(args)
         ps.subscribe(key, func)
     end
 
-    -- VISIBILITY --
+    -- VISIBILITY & ANIMATIONS --
 
-    -- show the element
-    function public.show()
+    -- show the element and enables animations by default
+    ---@param animate? boolean true (default) to automatically resume animations
+    function public.show(animate)
         protected.window.setVisible(true)
-        protected.start_anim()
-        for _, child in pairs(self.children) do child.show() end
+        if animate ~= false then public.animate_all() end
     end
 
-    -- hide the element
+    -- hide the element and disables animations<br>
+    -- this alone does not cause an element to be fully hidden, it only prevents updates from being shown<br>
+    ---@see graphics_element.content_redraw
     function public.hide()
-        protected.stop_anim()
-        for _, child in pairs(self.children) do child.hide() end
+        public.freeze_all() -- stop animations for efficiency/performance
         protected.window.setVisible(false)
     end
 
+    -- start/resume animation(s)
+    function public.animate()
+        protected.start_anim()
+    end
+
+    -- start/resume animation(s) for this element and all its children<br>
+    -- only animates if a window is visible
+    function public.animate_all()
+        if protected.window.isVisible() then
+            public.animate()
+            for _, child in pairs(protected.children) do child.animate_all() end
+        end
+    end
+
+    -- freeze animation(s)
+    function public.freeze()
+        protected.stop_anim()
+    end
+
+    -- freeze animation(s) for this element and all its children
+    function public.freeze_all()
+        public.freeze()
+        for _, child in pairs(protected.children) do child.freeze_all() end
+    end
+
     -- re-draw the element
     function public.redraw()
         protected.window.redraw()
     end
 
+    -- if a content window is set, clears it then re-draws all children
+    function public.content_redraw()
+        if protected.content_window ~= nil then
+            protected.content_window.clear()
+            for _, child in pairs(protected.children) do child.redraw() end
+        end
+    end
+
     return protected
 end
 
diff --git a/graphics/elements/animations/waiting.lua b/graphics/elements/animations/waiting.lua
index a0d7b3e..286c82e 100644
--- a/graphics/elements/animations/waiting.lua
+++ b/graphics/elements/animations/waiting.lua
@@ -1,6 +1,6 @@
 -- Loading/Waiting Animation Graphics Element
 
-local tcd     = require("scada-common.tcallbackdsp")
+local tcd     = require("scada-common.tcd")
 
 local element = require("graphics.element")
 
@@ -10,6 +10,7 @@ local element = require("graphics.element")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new waiting animation element
 ---@param args waiting_args
@@ -102,7 +103,7 @@ local function waiting(args)
 
     e.start_anim()
 
-    return e.get()
+    return e.complete()
 end
 
 return waiting
diff --git a/graphics/elements/colormap.lua b/graphics/elements/colormap.lua
index 4c7ba94..be92d83 100644
--- a/graphics/elements/colormap.lua
+++ b/graphics/elements/colormap.lua
@@ -9,6 +9,7 @@ local element = require("graphics.element")
 ---@field id? string element id
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
+---@field hidden? boolean true to hide on initial draw
 
 -- new color map
 ---@param args colormap_args
@@ -27,7 +28,7 @@ local function colormap(args)
     e.window.setCursorPos(1, 1)
     e.window.blit(spaces, bkg, bkg)
 
-    return e.get()
+    return e.complete()
 end
 
 return colormap
diff --git a/graphics/elements/controls/hazard_button.lua b/graphics/elements/controls/hazard_button.lua
index 4dca5c4..4745f4f 100644
--- a/graphics/elements/controls/hazard_button.lua
+++ b/graphics/elements/controls/hazard_button.lua
@@ -1,6 +1,6 @@
 -- Hazard-bordered Button Graphics Element
 
-local tcd     = require("scada-common.tcallbackdsp")
+local tcd     = require("scada-common.tcd")
 local util    = require("scada-common.util")
 
 local core    = require("graphics.core")
@@ -16,6 +16,7 @@ local element = require("graphics.element")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new hazard button
 ---@param args hazard_button_args
@@ -198,7 +199,7 @@ local function hazard_button(args)
     -- initial draw of border
     draw_border(args.accent)
 
-    return e.get()
+    return e.complete()
 end
 
 return hazard_button
diff --git a/graphics/elements/controls/multi_button.lua b/graphics/elements/controls/multi_button.lua
index e44bad0..279c9a7 100644
--- a/graphics/elements/controls/multi_button.lua
+++ b/graphics/elements/controls/multi_button.lua
@@ -23,6 +23,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field height? integer parent height if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new multi button (latch selection, exclusively one button at a time)
 ---@param args multi_button_args
@@ -130,7 +131,7 @@ local function multi_button(args)
     -- initial draw
     draw()
 
-    return e.get()
+    return e.complete()
 end
 
 return multi_button
diff --git a/graphics/elements/controls/push_button.lua b/graphics/elements/controls/push_button.lua
index 27be991..e6f4920 100644
--- a/graphics/elements/controls/push_button.lua
+++ b/graphics/elements/controls/push_button.lua
@@ -1,6 +1,6 @@
 -- Button Graphics Element
 
-local tcd     = require("scada-common.tcallbackdsp")
+local tcd     = require("scada-common.tcd")
 
 local core    = require("graphics.core")
 local element = require("graphics.element")
@@ -19,6 +19,7 @@ local CLICK_TYPE = core.events.CLICK_TYPE
 ---@field y? integer 1 if omitted
 ---@field height? integer parent height if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new push button
 ---@param args push_button_args
@@ -120,7 +121,7 @@ local function push_button(args)
     -- initial draw
     draw()
 
-    return e.get()
+    return e.complete()
 end
 
 return push_button
diff --git a/graphics/elements/controls/radio_button.lua b/graphics/elements/controls/radio_button.lua
index 050bf39..e3edf24 100644
--- a/graphics/elements/controls/radio_button.lua
+++ b/graphics/elements/controls/radio_button.lua
@@ -15,6 +15,7 @@ local element = require("graphics.element")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new radio button list (latch selection, exclusively one button at a time)
 ---@param args radio_button_args
@@ -103,7 +104,7 @@ local function radio_button(args)
     -- initial draw
     draw()
 
-    return e.get()
+    return e.complete()
 end
 
 return radio_button
diff --git a/graphics/elements/controls/sidebar.lua b/graphics/elements/controls/sidebar.lua
index 45771b2..d43317a 100644
--- a/graphics/elements/controls/sidebar.lua
+++ b/graphics/elements/controls/sidebar.lua
@@ -1,6 +1,6 @@
 -- Sidebar Graphics Element
 
-local tcd     = require("scada-common.tcallbackdsp")
+local tcd     = require("scada-common.tcd")
 
 local core    = require("graphics.core")
 local element = require("graphics.element")
@@ -20,6 +20,7 @@ local CLICK_TYPE = core.events.CLICK_TYPE
 ---@field y? integer 1 if omitted
 ---@field height? integer parent height if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new sidebar tab selector
 ---@param args sidebar_args
@@ -115,7 +116,7 @@ local function sidebar(args)
     -- initial draw
     draw(false)
 
-    return e.get()
+    return e.complete()
 end
 
 return sidebar
diff --git a/graphics/elements/controls/spinbox_numeric.lua b/graphics/elements/controls/spinbox_numeric.lua
index 6b88c0e..767d97b 100644
--- a/graphics/elements/controls/spinbox_numeric.lua
+++ b/graphics/elements/controls/spinbox_numeric.lua
@@ -18,6 +18,7 @@ local element = require("graphics.element")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new spinbox control (minimum value is 0)
 ---@param args spinbox_args
@@ -188,7 +189,7 @@ local function spinbox(args)
     e.value = 0
     set_digits()
 
-    return e.get()
+    return e.complete()
 end
 
 return spinbox
diff --git a/graphics/elements/controls/switch_button.lua b/graphics/elements/controls/switch_button.lua
index 645bf8a..6d2e09c 100644
--- a/graphics/elements/controls/switch_button.lua
+++ b/graphics/elements/controls/switch_button.lua
@@ -15,6 +15,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field height? integer parent height if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new switch button (latch high/low)
 ---@param args switch_button_args
@@ -86,7 +87,7 @@ local function switch_button(args)
         draw_state()
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return switch_button
diff --git a/graphics/elements/controls/tabbar.lua b/graphics/elements/controls/tabbar.lua
index 6249951..da4738b 100644
--- a/graphics/elements/controls/tabbar.lua
+++ b/graphics/elements/controls/tabbar.lua
@@ -21,6 +21,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field width? integer parent width if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new tab selector
 ---@param args tabbar_args
@@ -124,7 +125,7 @@ local function tabbar(args)
     -- initial draw
     draw()
 
-    return e.get()
+    return e.complete()
 end
 
 return tabbar
diff --git a/graphics/elements/displaybox.lua b/graphics/elements/displaybox.lua
index c7e5c9f..3578a63 100644
--- a/graphics/elements/displaybox.lua
+++ b/graphics/elements/displaybox.lua
@@ -4,19 +4,22 @@ local element = require("graphics.element")
 
 ---@class displaybox_args
 ---@field window table
+---@field id? string element id
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field width? integer parent width if omitted
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new root display box
 ---@nodiscard
 ---@param args displaybox_args
+---@return graphics_element element, element_id id
 local function displaybox(args)
     -- create new graphics element base object
-    return element.new(args).get()
+    return element.new(args).complete()
 end
 
 return displaybox
diff --git a/graphics/elements/div.lua b/graphics/elements/div.lua
index 5eeef71..4b6bd6a 100644
--- a/graphics/elements/div.lua
+++ b/graphics/elements/div.lua
@@ -11,6 +11,7 @@ local element = require("graphics.element")
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new div element
 ---@nodiscard
@@ -18,7 +19,7 @@ local element = require("graphics.element")
 ---@return graphics_element element, element_id id
 local function div(args)
     -- create new graphics element base object
-    return element.new(args).get()
+    return element.new(args).complete()
 end
 
 return div
diff --git a/graphics/elements/indicators/alight.lua b/graphics/elements/indicators/alight.lua
index 8bb8fa6..ff9b1ad 100644
--- a/graphics/elements/indicators/alight.lua
+++ b/graphics/elements/indicators/alight.lua
@@ -18,6 +18,7 @@ local flasher = require("graphics.flasher")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new alarm indicator light
 ---@nodiscard
@@ -108,7 +109,7 @@ local function alarm_indicator_light(args)
     e.on_update(1)
     e.window.write(args.label)
 
-    return e.get()
+    return e.complete()
 end
 
 return alarm_indicator_light
diff --git a/graphics/elements/indicators/coremap.lua b/graphics/elements/indicators/coremap.lua
index 05434a3..127a8a3 100644
--- a/graphics/elements/indicators/coremap.lua
+++ b/graphics/elements/indicators/coremap.lua
@@ -163,7 +163,7 @@ local function core_map(args)
     -- initial draw
     e.on_update(0)
 
-    return e.get()
+    return e.complete()
 end
 
 return core_map
diff --git a/graphics/elements/indicators/data.lua b/graphics/elements/indicators/data.lua
index 66d45dc..9282a03 100644
--- a/graphics/elements/indicators/data.lua
+++ b/graphics/elements/indicators/data.lua
@@ -17,6 +17,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field width integer length
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new data indicator
 ---@nodiscard
@@ -43,8 +44,9 @@ local function data(args)
     e.window.setCursorPos(1, 1)
     e.window.write(args.label)
 
-    local label_len = string.len(args.label)
-    local data_start = 1
+    local value_color = e.fg_bg.fgd
+    local label_len   = string.len(args.label)
+    local data_start  = 1
     local clear_width = args.width
 
     if label_len > 0 then
@@ -64,7 +66,7 @@ local function data(args)
         -- write data
         local data_str = util.sprintf(args.format, value)
         e.window.setCursorPos(data_start, 1)
-        e.window.setTextColor(e.fg_bg.fgd)
+        e.window.setTextColor(value_color)
         if args.commas then
             e.window.write(util.comma_format(data_str))
         else
@@ -84,10 +86,17 @@ local function data(args)
     ---@param val any new value
     function e.set_value(val) e.on_update(val) end
 
+    -- change the foreground color of the value, or all text if no label/unit colors provided
+    ---@param c color
+    function e.recolor(c)
+        value_color = c
+        e.on_update(e.value)
+    end
+
     -- initial value draw
     e.on_update(args.value)
 
-    return e.get()
+    return e.complete()
 end
 
 return data
diff --git a/graphics/elements/indicators/hbar.lua b/graphics/elements/indicators/hbar.lua
index 2d9b110..9bee59f 100644
--- a/graphics/elements/indicators/hbar.lua
+++ b/graphics/elements/indicators/hbar.lua
@@ -15,6 +15,7 @@ local element = require("graphics.element")
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new horizontal bar
 ---@nodiscard
@@ -119,7 +120,7 @@ local function hbar(args)
     -- initialize to 0
     e.on_update(0)
 
-    return e.get()
+    return e.complete()
 end
 
 return hbar
diff --git a/graphics/elements/indicators/icon.lua b/graphics/elements/indicators/icon.lua
index f31479d..03c88fb 100644
--- a/graphics/elements/indicators/icon.lua
+++ b/graphics/elements/indicators/icon.lua
@@ -18,6 +18,7 @@ local element = require("graphics.element")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new icon indicator
 ---@nodiscard
@@ -68,7 +69,7 @@ local function icon(args)
     -- initial icon draw
     e.on_update(args.value or 1)
 
-    return e.get()
+    return e.complete()
 end
 
 return icon
diff --git a/graphics/elements/indicators/led.lua b/graphics/elements/indicators/led.lua
index dd2264e..077cab3 100644
--- a/graphics/elements/indicators/led.lua
+++ b/graphics/elements/indicators/led.lua
@@ -16,6 +16,7 @@ local flasher = require("graphics.flasher")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new indicator LED
 ---@nodiscard
@@ -94,7 +95,7 @@ local function indicator_led(args)
         e.window.write(args.label)
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return indicator_led
diff --git a/graphics/elements/indicators/ledpair.lua b/graphics/elements/indicators/ledpair.lua
index 727d4cd..47c9a0a 100644
--- a/graphics/elements/indicators/ledpair.lua
+++ b/graphics/elements/indicators/ledpair.lua
@@ -18,6 +18,7 @@ local flasher = require("graphics.flasher")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new dual LED indicator light
 ---@nodiscard
@@ -108,7 +109,7 @@ local function indicator_led_pair(args)
         e.window.write(args.label)
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return indicator_led_pair
diff --git a/graphics/elements/indicators/ledrgb.lua b/graphics/elements/indicators/ledrgb.lua
index 266e0ab..dbcb947 100644
--- a/graphics/elements/indicators/ledrgb.lua
+++ b/graphics/elements/indicators/ledrgb.lua
@@ -11,6 +11,7 @@ local element = require("graphics.element")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new RGB LED indicator light
 ---@nodiscard
@@ -53,7 +54,7 @@ local function indicator_led_rgb(args)
         e.window.write(args.label)
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return indicator_led_rgb
diff --git a/graphics/elements/indicators/light.lua b/graphics/elements/indicators/light.lua
index e764ad9..d4e8b09 100644
--- a/graphics/elements/indicators/light.lua
+++ b/graphics/elements/indicators/light.lua
@@ -16,6 +16,7 @@ local flasher = require("graphics.flasher")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new indicator light
 ---@nodiscard
@@ -92,7 +93,7 @@ local function indicator_light(args)
     e.window.setCursorPos(3, 1)
     e.window.write(args.label)
 
-    return e.get()
+    return e.complete()
 end
 
 return indicator_light
diff --git a/graphics/elements/indicators/power.lua b/graphics/elements/indicators/power.lua
index 1d727ae..323fe58 100644
--- a/graphics/elements/indicators/power.lua
+++ b/graphics/elements/indicators/power.lua
@@ -16,6 +16,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field width integer length
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new power indicator
 ---@nodiscard
@@ -79,7 +80,7 @@ local function power(args)
     -- initial value draw
     e.on_update(args.value)
 
-    return e.get()
+    return e.complete()
 end
 
 return power
diff --git a/graphics/elements/indicators/rad.lua b/graphics/elements/indicators/rad.lua
index 2e4ad56..fc89044 100644
--- a/graphics/elements/indicators/rad.lua
+++ b/graphics/elements/indicators/rad.lua
@@ -17,6 +17,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field width integer length
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new radiation indicator
 ---@nodiscard
@@ -84,7 +85,7 @@ local function rad(args)
     -- initial value draw
     e.on_update(types.new_zero_radiation_reading())
 
-    return e.get()
+    return e.complete()
 end
 
 return rad
diff --git a/graphics/elements/indicators/state.lua b/graphics/elements/indicators/state.lua
index 10d081b..d0e57b5 100644
--- a/graphics/elements/indicators/state.lua
+++ b/graphics/elements/indicators/state.lua
@@ -18,6 +18,7 @@ local element = require("graphics.element")
 ---@field y? integer 1 if omitted
 ---@field height? integer 1 if omitted, must be an odd number
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new state indicator
 ---@nodiscard
@@ -74,7 +75,7 @@ local function state_indicator(args)
     -- initial draw
     e.on_update(args.value or 1)
 
-    return e.get()
+    return e.complete()
 end
 
 return state_indicator
diff --git a/graphics/elements/indicators/trilight.lua b/graphics/elements/indicators/trilight.lua
index 543ebf5..ef8a8b6 100644
--- a/graphics/elements/indicators/trilight.lua
+++ b/graphics/elements/indicators/trilight.lua
@@ -18,6 +18,7 @@ local flasher = require("graphics.flasher")
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new tri-state indicator light
 ---@nodiscard
@@ -105,7 +106,7 @@ local function tristate_indicator_light(args)
     e.on_update(1)
     e.window.write(args.label)
 
-    return e.get()
+    return e.complete()
 end
 
 return tristate_indicator_light
diff --git a/graphics/elements/indicators/vbar.lua b/graphics/elements/indicators/vbar.lua
index fe7f9bc..4cfb6e7 100644
--- a/graphics/elements/indicators/vbar.lua
+++ b/graphics/elements/indicators/vbar.lua
@@ -13,6 +13,7 @@ local element = require("graphics.element")
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new vertical bar
 ---@nodiscard
@@ -99,7 +100,7 @@ local function vbar(args)
     ---@param val number 0.0 to 1.0
     function e.set_value(val) e.on_update(val) end
 
-    return e.get()
+    return e.complete()
 end
 
 return vbar
diff --git a/graphics/elements/listbox.lua b/graphics/elements/listbox.lua
new file mode 100644
index 0000000..e37a772
--- /dev/null
+++ b/graphics/elements/listbox.lua
@@ -0,0 +1,283 @@
+-- Scroll-able List Box Display Graphics Element
+
+local tcd     = require("scada-common.tcd")
+
+local core    = require("graphics.core")
+local element = require("graphics.element")
+
+local CLICK_TYPE = core.events.CLICK_TYPE
+
+---@class listbox_args
+---@field scroll_height integer height of internal scrolling container (must fit all elements vertically tiled)
+---@field item_pad? integer spacing (lines) between items in the list (default 0)
+---@field nav_fg_bg? cpair foreground/background colors for scroll arrows and bar area
+---@field nav_active? cpair active colors for bar held down or arrow held down
+---@field parent graphics_element
+---@field id? string element id
+---@field x? integer 1 if omitted
+---@field y? integer 1 if omitted
+---@field width? integer parent width if omitted
+---@field height? integer parent height if omitted
+---@field gframe? graphics_frame frame instead of x/y/width/height
+---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
+
+---@class listbox_item
+---@field id string|integer element ID
+---@field e graphics_element element
+---@field y integer y position
+---@field h integer element height
+
+-- new listbox element
+---@nodiscard
+---@param args listbox_args
+---@return graphics_element element, element_id id
+local function listbox(args)
+    -- create new graphics element base object
+    local e = element.new(args)
+
+    -- create content window for child elements
+    local scroll_frame = window.create(e.window, 1, 1, e.frame.w - 1, args.scroll_height, false)
+    e.content_window = scroll_frame
+
+    -- item list and scroll management
+    local list            = {}
+    local item_pad        = args.item_pad or 0
+    local scroll_offset   = 0
+    local content_height  = 0
+    local max_down_scroll = 0
+    -- bar control/tracking variables
+    local max_bar_height  = e.frame.h - 2
+    local bar_height      = 0           -- full height of bar
+    local bar_bounds      = { 0, 0 }    -- top and bottom of bar
+    local bar_is_scaled   = false       -- if the scrollbar doesn't have a 1:1 ratio with lines
+    local holding_bar     = false       -- bar is being held by mouse
+    local bar_grip_pos    = 0           -- where the bar was gripped by mouse down
+    local mouse_last_y    = 0           -- last reported y coordinate of drag
+
+    -- draw scroll bar arrows, optionally showing one of them as pressed
+    ---@param pressed_arrow? 1|0|-1 arrow to show as pressed (1 = scroll up, 0 = neither, -1 = scroll down)
+    local function draw_arrows(pressed_arrow)
+        local nav_fg_bg = args.nav_fg_bg or e.fg_bg
+        local active_fg_bg = args.nav_active or nav_fg_bg
+
+        -- draw up/down arrows
+        if pressed_arrow == 1 then
+            e.window.setTextColor(active_fg_bg.fgd)
+            e.window.setBackgroundColor(active_fg_bg.bkg)
+            e.window.setCursorPos(e.frame.w, 1)
+            e.window.write("\x1e")
+            e.window.setTextColor(nav_fg_bg.fgd)
+            e.window.setBackgroundColor(nav_fg_bg.bkg)
+            e.window.setCursorPos(e.frame.w, e.frame.h)
+            e.window.write("\x1f")
+        elseif pressed_arrow == -1 then
+            e.window.setTextColor(nav_fg_bg.fgd)
+            e.window.setBackgroundColor(nav_fg_bg.bkg)
+            e.window.setCursorPos(e.frame.w, 1)
+            e.window.write("\x1e")
+            e.window.setTextColor(active_fg_bg.fgd)
+            e.window.setBackgroundColor(active_fg_bg.bkg)
+            e.window.setCursorPos(e.frame.w, e.frame.h)
+            e.window.write("\x1f")
+        else
+            e.window.setTextColor(nav_fg_bg.fgd)
+            e.window.setBackgroundColor(nav_fg_bg.bkg)
+            e.window.setCursorPos(e.frame.w, 1)
+            e.window.write("\x1e")
+            e.window.setCursorPos(e.frame.w, e.frame.h)
+            e.window.write("\x1f")
+        end
+
+        e.window.setTextColor(e.fg_bg.fgd)
+        e.window.setBackgroundColor(e.fg_bg.bkg)
+    end
+
+    -- render the scroll bar and re-cacluate height & bounds
+    local function draw_bar()
+        local offset = 2 + math.abs(scroll_offset)
+
+        bar_height = math.min(max_bar_height + max_down_scroll, max_bar_height)
+
+        if bar_height < 1 then
+            bar_is_scaled = true
+            -- can't do a 1:1 ratio
+            -- use minimum size bar with scaled offset
+            local scroll_progress = scroll_offset / max_down_scroll
+            offset = 2 + math.floor(scroll_progress * (max_bar_height - 1))
+            bar_height = 1
+        else
+            bar_is_scaled = false
+        end
+
+        bar_bounds = { offset, (bar_height + offset) - 1 }
+
+        for i = 2, e.frame.h - 1 do
+            if (i >= offset and i < (bar_height + offset)) and (bar_height ~= max_bar_height) then
+                if args.nav_fg_bg ~= nil then
+                    e.window.setBackgroundColor(args.nav_fg_bg.fgd)
+                else
+                    e.window.setBackgroundColor(e.fg_bg.fgd)
+                end
+            else
+                if args.nav_fg_bg ~= nil then
+                    e.window.setBackgroundColor(args.nav_fg_bg.bkg)
+                else
+                    e.window.setBackgroundColor(e.fg_bg.bkg)
+                end
+            end
+
+            e.window.setCursorPos(e.frame.w, i)
+            e.window.write(" ")
+        end
+
+        e.window.setBackgroundColor(e.fg_bg.bkg)
+    end
+
+    -- update item y positions and move elements
+    local function update_positions()
+        local next_y = 1
+
+        scroll_frame.setVisible(false)
+        scroll_frame.setBackgroundColor(e.fg_bg.bkg)
+        scroll_frame.setTextColor(e.fg_bg.fgd)
+        scroll_frame.clear()
+
+        for i = 1, #list do
+            local item = list[i]    ---@type listbox_item
+            item.y = next_y
+            next_y = next_y + item.h + item_pad
+            item.e.reposition(1, item.y)
+            item.e.show()
+        end
+
+        content_height = next_y
+        max_down_scroll = math.min(-1 * (content_height - (e.frame.h + 1 + item_pad)), 0)
+        if scroll_offset < max_down_scroll then scroll_offset = max_down_scroll end
+
+        scroll_frame.reposition(1, 1 + scroll_offset)
+        scroll_frame.setVisible(true)
+
+        draw_bar()
+    end
+
+    -- determine where to scroll to based on a scrollbar being dragged without a 1:1 relationship
+    ---@param direction -1|1 negative 1 to scroll up by one, positive 1 to scroll down by one
+    local function scaled_bar_scroll(direction)
+        local scroll_progress = scroll_offset / max_down_scroll
+        local bar_position = math.floor(scroll_progress * (max_bar_height - 1))
+
+        -- check what moving the scroll bar up or down would mean for the scroll progress
+        scroll_progress = (bar_position + direction) / (max_bar_height - 1)
+
+        return math.max(math.floor(scroll_progress * max_down_scroll), max_down_scroll)
+    end
+
+    -- scroll down the list
+    local function scroll_down(scaled)
+        if scroll_offset > max_down_scroll then
+            if scaled then
+                scroll_offset = scaled_bar_scroll(1)
+            else
+                scroll_offset = scroll_offset - 1
+            end
+
+            update_positions()
+        end
+    end
+
+    -- scroll up the list
+    local function scroll_up(scaled)
+        if scroll_offset < 0 then
+            if scaled then
+                scroll_offset = scaled_bar_scroll(-1)
+            else
+                scroll_offset = scroll_offset + 1
+            end
+
+            update_positions()
+        end
+    end
+
+    -- handle a child element having been added to the list
+    ---@param id element_id element identifier
+    ---@param child graphics_element child element
+    function e.on_added(id, child)
+        table.insert(list, { id = id, e = child, y = 0, h = child.get_height() })
+        update_positions()
+    end
+
+    -- handle a child element having been removed from the list
+    ---@param id element_id element identifier
+    function e.on_removed(id)
+        for idx, elem in ipairs(list) do
+            if elem.id == id then
+                table.remove(list, idx)
+                update_positions()
+                return
+            end
+        end
+    end
+
+    -- handle mouse interaction
+    ---@param event mouse_interaction mouse event
+    function e.handle_mouse(event)
+        if e.enabled then
+            if event.type == CLICK_TYPE.TAP then
+                if event.current.x == e.frame.w then
+                    if event.current.y == 1 or event.current.y < bar_bounds[1] then
+                        draw_arrows(1)
+                        scroll_up()
+                        if args.nav_active ~= nil then tcd.dispatch(0.25, function () draw_arrows(0) end) end
+                    elseif event.current.y == e.frame.h or event.current.y > bar_bounds[2] then
+                        draw_arrows(-1)
+                        scroll_down()
+                        if args.nav_active ~= nil then tcd.dispatch(0.25, function () draw_arrows(0) end) end
+                    end
+                end
+            elseif event.type == CLICK_TYPE.DOWN then
+                if event.current.x == e.frame.w then
+                    if event.current.y == 1 or event.current.y < bar_bounds[1] then
+                        draw_arrows(1)
+                        scroll_up()
+                    elseif event.current.y == e.frame.h or event.current.y > bar_bounds[2] then
+                        draw_arrows(-1)
+                        scroll_down()
+                    else
+                        -- clicked on bar
+                        holding_bar = true
+                        bar_grip_pos = event.current.y - bar_bounds[1]
+                        mouse_last_y = event.current.y
+                    end
+                end
+            elseif event.type == CLICK_TYPE.UP then
+                holding_bar = false
+                draw_arrows(0)
+            elseif event.type == CLICK_TYPE.DRAG then
+                if holding_bar then
+                    -- if mouse is within vertical frame, including the grip point
+                    if event.current.y > (1 + bar_grip_pos) and event.current.y <= ((e.frame.h - bar_height) + bar_grip_pos) then
+                        if event.current.y < mouse_last_y then
+                            scroll_up(bar_is_scaled)
+                        elseif event.current.y > mouse_last_y then
+                            scroll_down(bar_is_scaled)
+                        end
+
+                        mouse_last_y = event.current.y
+                    end
+                end
+            elseif event.type == CLICK_TYPE.SCROLL_DOWN then
+                scroll_down()
+            elseif event.type == CLICK_TYPE.SCROLL_UP then
+                scroll_up()
+            end
+        end
+    end
+
+    draw_arrows(0)
+    draw_bar()
+
+    return e.complete()
+end
+
+return listbox
diff --git a/graphics/elements/multipane.lua b/graphics/elements/multipane.lua
index 8e25bab..790b595 100644
--- a/graphics/elements/multipane.lua
+++ b/graphics/elements/multipane.lua
@@ -12,6 +12,7 @@ local element = require("graphics.element")
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new multipane element
 ---@nodiscard
@@ -36,7 +37,7 @@ local function multipane(args)
 
     e.set_value(1)
 
-    return e.get()
+    return e.complete()
 end
 
 return multipane
diff --git a/graphics/elements/pipenet.lua b/graphics/elements/pipenet.lua
index 8a1d29b..5ca4745 100644
--- a/graphics/elements/pipenet.lua
+++ b/graphics/elements/pipenet.lua
@@ -12,6 +12,7 @@ local element = require("graphics.element")
 ---@field id? string element id
 ---@field x? integer 1 if omitted
 ---@field y? integer 1 if omitted
+---@field hidden? boolean true to hide on initial draw
 
 -- new pipe network
 ---@param args pipenet_args
@@ -141,7 +142,7 @@ local function pipenet(args)
 
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return pipenet
diff --git a/graphics/elements/rectangle.lua b/graphics/elements/rectangle.lua
index 2f7a68d..cd4b8cf 100644
--- a/graphics/elements/rectangle.lua
+++ b/graphics/elements/rectangle.lua
@@ -16,6 +16,7 @@ local element = require("graphics.element")
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new rectangle
 ---@param args rectangle_args
@@ -30,27 +31,35 @@ local function rectangle(args)
     end
 
     -- offset children
+    local offset_x = 0
+    local offset_y = 0
     if args.border ~= nil then
-        args.offset_x = args.border.width
-        args.offset_y = args.border.width
+        offset_x = args.border.width
+        offset_y = args.border.width
 
         -- slightly different y offset if the border is set to even
         if args.border.even then
             local width_x2 = (2 * args.border.width)
-            args.offset_y = math.floor(width_x2 / 3) + util.trinary(width_x2 % 3 > 0, 1, 0)
+            offset_y = math.floor(width_x2 / 3) + util.trinary(width_x2 % 3 > 0, 1, 0)
         end
     end
 
     -- create new graphics element base object
     local e = element.new(args)
 
+    -- create content window for child elements
+    e.content_window = window.create(e.window, 1 + offset_x, 1 + offset_y, e.frame.w - (2 * offset_x), e.frame.h - (2 * offset_y))
+    e.content_window.setBackgroundColor(e.fg_bg.bkg)
+    e.content_window.setTextColor(e.fg_bg.fgd)
+    e.content_window.clear()
+
     -- draw bordered box if requested
     -- element constructor will have drawn basic colored rectangle regardless
     if args.border ~= nil then
         e.window.setCursorPos(1, 1)
 
-        local border_width = args.offset_x
-        local border_height = args.offset_y
+        local border_width = offset_x
+        local border_height = offset_y
         local border_blit = colors.toBlit(args.border.color)
         local width_x2 = border_width * 2
         local inner_width = e.frame.w - width_x2
@@ -177,7 +186,7 @@ local function rectangle(args)
         end
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return rectangle
diff --git a/graphics/elements/textbox.lua b/graphics/elements/textbox.lua
index 9066deb..e72571b 100644
--- a/graphics/elements/textbox.lua
+++ b/graphics/elements/textbox.lua
@@ -18,6 +18,7 @@ local TEXT_ALIGN = core.TEXT_ALIGN
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new text box
 ---@param args textbox_args
@@ -64,7 +65,7 @@ local function textbox(args)
         display_text(val)
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return textbox
diff --git a/graphics/elements/tiling.lua b/graphics/elements/tiling.lua
index a97438a..536ed45 100644
--- a/graphics/elements/tiling.lua
+++ b/graphics/elements/tiling.lua
@@ -16,6 +16,7 @@ local element = require("graphics.element")
 ---@field height? integer parent height if omitted
 ---@field gframe? graphics_frame frame instead of x/y/width/height
 ---@field fg_bg? cpair foreground/background colors
+---@field hidden? boolean true to hide on initial draw
 
 -- new tiling box
 ---@param args tiling_args
@@ -81,7 +82,7 @@ local function tiling(args)
         if inner_width % 2 == 0 then alternator = not alternator end
     end
 
-    return e.get()
+    return e.complete()
 end
 
 return tiling
diff --git a/graphics/flasher.lua b/graphics/flasher.lua
index 0a3d9ea..520fba7 100644
--- a/graphics/flasher.lua
+++ b/graphics/flasher.lua
@@ -2,7 +2,7 @@
 -- Indicator Light Flasher
 --
 
-local tcd = require("scada-common.tcallbackdsp")
+local tcd = require("scada-common.tcd")
 
 local flasher = {}
 
diff --git a/imgen.py b/imgen.py
index 9a1e194..1456f20 100644
--- a/imgen.py
+++ b/imgen.py
@@ -111,7 +111,7 @@ f.close()
 if len(sys.argv) > 1 and sys.argv[1] == "shields":
     # write all the JSON files for shields.io
     for key, version in final_manifest["versions"].items():
-        f = open("./shields/" + key + ".json", "w")
+        f = open("./deploy/" + key + ".json", "w")
 
         if version.find("alpha") >= 0:
             color = "yellow"
diff --git a/install_manifest.json b/install_manifest.json
index d1b808d..1a6bde2 100644
--- a/install_manifest.json
+++ b/install_manifest.json
@@ -1 +1 @@
-{"versions": {"installer": "v1.0", "bootloader": "0.2", "comms": "1.4.1", "reactor-plc": "v1.3.2", "rtu": "v1.2.2", "supervisor": "v0.15.9", "coordinator": "v0.15.2", "pocket": "alpha-v0.3.2"}, "files": {"system": ["initenv.lua", "startup.lua"], "common": ["scada-common/crypto.lua", "scada-common/ppm.lua", "scada-common/comms.lua", "scada-common/psil.lua", "scada-common/tcallbackdsp.lua", "scada-common/rsio.lua", "scada-common/constants.lua", "scada-common/mqueue.lua", "scada-common/crash.lua", "scada-common/log.lua", "scada-common/types.lua", "scada-common/util.lua"], "graphics": ["graphics/element.lua", "graphics/events.lua", "graphics/flasher.lua", "graphics/core.lua", "graphics/elements/textbox.lua", "graphics/elements/displaybox.lua", "graphics/elements/pipenet.lua", "graphics/elements/rectangle.lua", "graphics/elements/div.lua", "graphics/elements/multipane.lua", "graphics/elements/tiling.lua", "graphics/elements/colormap.lua", "graphics/elements/indicators/alight.lua", "graphics/elements/indicators/icon.lua", "graphics/elements/indicators/power.lua", "graphics/elements/indicators/rad.lua", "graphics/elements/indicators/state.lua", "graphics/elements/indicators/light.lua", "graphics/elements/indicators/vbar.lua", "graphics/elements/indicators/led.lua", "graphics/elements/indicators/coremap.lua", "graphics/elements/indicators/data.lua", "graphics/elements/indicators/ledpair.lua", "graphics/elements/indicators/hbar.lua", "graphics/elements/indicators/trilight.lua", "graphics/elements/indicators/ledrgb.lua", "graphics/elements/controls/switch_button.lua", "graphics/elements/controls/spinbox_numeric.lua", "graphics/elements/controls/hazard_button.lua", "graphics/elements/controls/push_button.lua", "graphics/elements/controls/radio_button.lua", "graphics/elements/controls/multi_button.lua", "graphics/elements/controls/tabbar.lua", "graphics/elements/controls/sidebar.lua", "graphics/elements/animations/waiting.lua"], "lockbox": ["lockbox/init.lua", "lockbox/LICENSE", "lockbox/kdf/pbkdf2.lua", "lockbox/util/bit.lua", "lockbox/util/array.lua", "lockbox/util/stream.lua", "lockbox/util/queue.lua", "lockbox/digest/sha2_224.lua", "lockbox/digest/sha1.lua", "lockbox/digest/sha2_256.lua", "lockbox/cipher/aes128.lua", "lockbox/cipher/aes256.lua", "lockbox/cipher/aes192.lua", "lockbox/cipher/mode/ofb.lua", "lockbox/cipher/mode/cbc.lua", "lockbox/cipher/mode/ctr.lua", "lockbox/cipher/mode/cfb.lua", "lockbox/mac/hmac.lua", "lockbox/padding/ansix923.lua", "lockbox/padding/pkcs7.lua", "lockbox/padding/zero.lua", "lockbox/padding/isoiec7816.lua"], "reactor-plc": ["reactor-plc/renderer.lua", "reactor-plc/threads.lua", "reactor-plc/databus.lua", "reactor-plc/plc.lua", "reactor-plc/config.lua", "reactor-plc/startup.lua", "reactor-plc/panel/front_panel.lua", "reactor-plc/panel/style.lua"], "rtu": ["rtu/renderer.lua", "rtu/threads.lua", "rtu/rtu.lua", "rtu/databus.lua", "rtu/modbus.lua", "rtu/config.lua", "rtu/startup.lua", "rtu/panel/front_panel.lua", "rtu/panel/style.lua", "rtu/dev/sps_rtu.lua", "rtu/dev/envd_rtu.lua", "rtu/dev/boilerv_rtu.lua", "rtu/dev/redstone_rtu.lua", "rtu/dev/sna_rtu.lua", "rtu/dev/imatrix_rtu.lua", "rtu/dev/turbinev_rtu.lua"], "supervisor": ["supervisor/supervisor.lua", "supervisor/unit.lua", "supervisor/config.lua", "supervisor/startup.lua", "supervisor/unitlogic.lua", "supervisor/facility.lua", "supervisor/session/coordinator.lua", "supervisor/session/svqtypes.lua", "supervisor/session/pocket.lua", "supervisor/session/svsessions.lua", "supervisor/session/rtu.lua", "supervisor/session/plc.lua", "supervisor/session/rsctl.lua", "supervisor/session/rtu/boilerv.lua", "supervisor/session/rtu/txnctrl.lua", "supervisor/session/rtu/unit_session.lua", "supervisor/session/rtu/turbinev.lua", "supervisor/session/rtu/envd.lua", "supervisor/session/rtu/imatrix.lua", "supervisor/session/rtu/sps.lua", "supervisor/session/rtu/qtypes.lua", "supervisor/session/rtu/sna.lua", "supervisor/session/rtu/redstone.lua"], "coordinator": ["coordinator/coordinator.lua", "coordinator/renderer.lua", "coordinator/iocontrol.lua", "coordinator/sounder.lua", "coordinator/config.lua", "coordinator/startup.lua", "coordinator/process.lua", "coordinator/ui/dialog.lua", "coordinator/ui/style.lua", "coordinator/ui/layout/main_view.lua", "coordinator/ui/layout/unit_view.lua", "coordinator/ui/components/reactor.lua", "coordinator/ui/components/processctl.lua", "coordinator/ui/components/unit_overview.lua", "coordinator/ui/components/boiler.lua", "coordinator/ui/components/unit_detail.lua", "coordinator/ui/components/imatrix.lua", "coordinator/ui/components/turbine.lua", "coordinator/session/api.lua", "coordinator/session/apisessions.lua"], "pocket": ["pocket/pocket.lua", "pocket/renderer.lua", "pocket/config.lua", "pocket/coreio.lua", "pocket/startup.lua", "pocket/ui/main.lua", "pocket/ui/style.lua", "pocket/ui/components/turbine_page.lua", "pocket/ui/components/reactor_page.lua", "pocket/ui/components/home_page.lua", "pocket/ui/components/unit_page.lua", "pocket/ui/components/boiler_page.lua", "pocket/ui/components/conn_waiting.lua"]}, "depends": {"reactor-plc": ["system", "common", "graphics"], "rtu": ["system", "common", "graphics"], "supervisor": ["system", "common"], "coordinator": ["system", "common", "graphics"], "pocket": ["system", "common", "graphics"]}, "sizes": {"manifest": 5530, "system": 1991, "common": 91102, "graphics": 129460, "lockbox": 100797, "reactor-plc": 95896, "rtu": 100982, "supervisor": 283073, "coordinator": 197508, "pocket": 36200}}
\ No newline at end of file
+{"versions": {"installer": "v1.2", "bootloader": "0.2", "comms": "2.0.0", "reactor-plc": "v1.4.5", "rtu": "v1.3.5", "supervisor": "v0.17.5", "coordinator": "v0.16.0", "pocket": "alpha-v0.4.4"}, "files": {"system": ["initenv.lua", "startup.lua"], "common": ["scada-common/crypto.lua", "scada-common/ppm.lua", "scada-common/comms.lua", "scada-common/psil.lua", "scada-common/rsio.lua", "scada-common/constants.lua", "scada-common/mqueue.lua", "scada-common/tcd.lua", "scada-common/crash.lua", "scada-common/log.lua", "scada-common/types.lua", "scada-common/util.lua"], "graphics": ["graphics/element.lua", "graphics/events.lua", "graphics/flasher.lua", "graphics/core.lua", "graphics/elements/listbox.lua", "graphics/elements/textbox.lua", "graphics/elements/displaybox.lua", "graphics/elements/pipenet.lua", "graphics/elements/rectangle.lua", "graphics/elements/div.lua", "graphics/elements/multipane.lua", "graphics/elements/tiling.lua", "graphics/elements/colormap.lua", "graphics/elements/indicators/alight.lua", "graphics/elements/indicators/icon.lua", "graphics/elements/indicators/power.lua", "graphics/elements/indicators/rad.lua", "graphics/elements/indicators/state.lua", "graphics/elements/indicators/light.lua", "graphics/elements/indicators/vbar.lua", "graphics/elements/indicators/led.lua", "graphics/elements/indicators/coremap.lua", "graphics/elements/indicators/data.lua", "graphics/elements/indicators/ledpair.lua", "graphics/elements/indicators/hbar.lua", "graphics/elements/indicators/trilight.lua", "graphics/elements/indicators/ledrgb.lua", "graphics/elements/controls/switch_button.lua", "graphics/elements/controls/spinbox_numeric.lua", "graphics/elements/controls/hazard_button.lua", "graphics/elements/controls/push_button.lua", "graphics/elements/controls/radio_button.lua", "graphics/elements/controls/multi_button.lua", "graphics/elements/controls/tabbar.lua", "graphics/elements/controls/sidebar.lua", "graphics/elements/animations/waiting.lua"], "lockbox": ["lockbox/init.lua", "lockbox/LICENSE", "lockbox/kdf/pbkdf2.lua", "lockbox/util/bit.lua", "lockbox/util/array.lua", "lockbox/util/stream.lua", "lockbox/util/queue.lua", "lockbox/digest/sha2_224.lua", "lockbox/digest/sha1.lua", "lockbox/digest/sha2_256.lua", "lockbox/cipher/aes128.lua", "lockbox/cipher/aes256.lua", "lockbox/cipher/aes192.lua", "lockbox/cipher/mode/ofb.lua", "lockbox/cipher/mode/cbc.lua", "lockbox/cipher/mode/ctr.lua", "lockbox/cipher/mode/cfb.lua", "lockbox/mac/hmac.lua", "lockbox/padding/ansix923.lua", "lockbox/padding/pkcs7.lua", "lockbox/padding/zero.lua", "lockbox/padding/isoiec7816.lua"], "reactor-plc": ["reactor-plc/renderer.lua", "reactor-plc/threads.lua", "reactor-plc/databus.lua", "reactor-plc/plc.lua", "reactor-plc/config.lua", "reactor-plc/startup.lua", "reactor-plc/panel/front_panel.lua", "reactor-plc/panel/style.lua"], "rtu": ["rtu/renderer.lua", "rtu/threads.lua", "rtu/rtu.lua", "rtu/databus.lua", "rtu/modbus.lua", "rtu/config.lua", "rtu/startup.lua", "rtu/panel/front_panel.lua", "rtu/panel/style.lua", "rtu/dev/sps_rtu.lua", "rtu/dev/envd_rtu.lua", "rtu/dev/boilerv_rtu.lua", "rtu/dev/redstone_rtu.lua", "rtu/dev/sna_rtu.lua", "rtu/dev/imatrix_rtu.lua", "rtu/dev/turbinev_rtu.lua"], "supervisor": ["supervisor/renderer.lua", "supervisor/databus.lua", "supervisor/supervisor.lua", "supervisor/unit.lua", "supervisor/config.lua", "supervisor/startup.lua", "supervisor/unitlogic.lua", "supervisor/facility.lua", "supervisor/panel/pgi.lua", "supervisor/panel/front_panel.lua", "supervisor/panel/style.lua", "supervisor/panel/components/rtu_entry.lua", "supervisor/panel/components/pdg_entry.lua", "supervisor/session/coordinator.lua", "supervisor/session/svqtypes.lua", "supervisor/session/pocket.lua", "supervisor/session/svsessions.lua", "supervisor/session/rtu.lua", "supervisor/session/plc.lua", "supervisor/session/rsctl.lua", "supervisor/session/rtu/boilerv.lua", "supervisor/session/rtu/txnctrl.lua", "supervisor/session/rtu/unit_session.lua", "supervisor/session/rtu/turbinev.lua", "supervisor/session/rtu/envd.lua", "supervisor/session/rtu/imatrix.lua", "supervisor/session/rtu/sps.lua", "supervisor/session/rtu/qtypes.lua", "supervisor/session/rtu/sna.lua", "supervisor/session/rtu/redstone.lua"], "coordinator": ["coordinator/coordinator.lua", "coordinator/renderer.lua", "coordinator/iocontrol.lua", "coordinator/sounder.lua", "coordinator/config.lua", "coordinator/startup.lua", "coordinator/process.lua", "coordinator/ui/dialog.lua", "coordinator/ui/style.lua", "coordinator/ui/layout/main_view.lua", "coordinator/ui/layout/unit_view.lua", "coordinator/ui/components/reactor.lua", "coordinator/ui/components/processctl.lua", "coordinator/ui/components/unit_overview.lua", "coordinator/ui/components/boiler.lua", "coordinator/ui/components/unit_detail.lua", "coordinator/ui/components/imatrix.lua", "coordinator/ui/components/turbine.lua", "coordinator/session/pocket.lua", "coordinator/session/apisessions.lua"], "pocket": ["pocket/pocket.lua", "pocket/renderer.lua", "pocket/config.lua", "pocket/coreio.lua", "pocket/startup.lua", "pocket/ui/main.lua", "pocket/ui/style.lua", "pocket/ui/components/conn_waiting.lua", "pocket/ui/pages/turbine_page.lua", "pocket/ui/pages/reactor_page.lua", "pocket/ui/pages/home_page.lua", "pocket/ui/pages/unit_page.lua", "pocket/ui/pages/boiler_page.lua"]}, "depends": {"reactor-plc": ["system", "common", "graphics"], "rtu": ["system", "common", "graphics"], "supervisor": ["system", "common"], "coordinator": ["system", "common", "graphics"], "pocket": ["system", "common", "graphics"]}, "sizes": {"manifest": 5769, "system": 1991, "common": 92736, "graphics": 144028, "lockbox": 100797, "reactor-plc": 97335, "rtu": 102240, "supervisor": 315402, "coordinator": 197991, "pocket": 37581}}
\ No newline at end of file
diff --git a/pocket/config.lua b/pocket/config.lua
index 27e1489..0c35b59 100644
--- a/pocket/config.lua
+++ b/pocket/config.lua
@@ -1,11 +1,11 @@
 local config = {}
 
--- port of the SCADA supervisor
-config.SCADA_SV_PORT = 16100
--- port for SCADA coordinator API access
-config.SCADA_API_PORT = 16200
--- port to listen to incoming packets FROM servers
-config.LISTEN_PORT = 16201
+-- supervisor comms channel
+config.SVR_CHANNEL = 16240
+-- coordinator comms channel
+config.CRD_CHANNEL = 16243
+-- pocket comms channel
+config.PKT_CHANNEL = 16244
 -- max trusted modem message distance (0 to disable check)
 config.TRUSTED_RANGE = 0
 -- time in seconds (>= 2) before assuming a remote device is no longer active
diff --git a/pocket/pocket.lua b/pocket/pocket.lua
index cc4d870..0281e92 100644
--- a/pocket/pocket.lua
+++ b/pocket/pocket.lua
@@ -18,22 +18,24 @@ local pocket = {}
 ---@nodiscard
 ---@param version string pocket version
 ---@param modem table modem device
----@param local_port integer local pocket port
----@param sv_port integer port of supervisor
----@param api_port integer port of coordinator API
+---@param pkt_channel integer pocket comms channel
+---@param svr_channel integer supervisor access channel
+---@param crd_channel integer coordinator access channel
 ---@param range integer trusted device connection range
 ---@param sv_watchdog watchdog
 ---@param api_watchdog watchdog
-function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_watchdog, api_watchdog)
+function pocket.comms(version, modem, pkt_channel, svr_channel, crd_channel, range, sv_watchdog, api_watchdog)
     local self = {
         sv = {
             linked = false,
+            addr = comms.BROADCAST,
             seq_num = 0,
             r_seq_num = nil,    ---@type nil|integer
             last_est_ack = ESTABLISH_ACK.ALLOW
         },
         api = {
             linked = false,
+            addr = comms.BROADCAST,
             seq_num = 0,
             r_seq_num = nil,    ---@type nil|integer
             last_est_ack = ESTABLISH_ACK.ALLOW
@@ -48,7 +50,7 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
     -- configure modem channels
     local function _conf_channels()
         modem.closeAll()
-        modem.open(local_port)
+        modem.open(pkt_channel)
     end
 
     _conf_channels()
@@ -61,9 +63,9 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
         local pkt = comms.mgmt_packet()
 
         pkt.make(msg_type, msg)
-        s_pkt.make(self.sv.seq_num, PROTOCOL.SCADA_MGMT, pkt.raw_sendable())
+        s_pkt.make(self.sv.addr, self.sv.seq_num, PROTOCOL.SCADA_MGMT, pkt.raw_sendable())
 
-        modem.transmit(sv_port, local_port, s_pkt.raw_sendable())
+        modem.transmit(svr_channel, pkt_channel, s_pkt.raw_sendable())
         self.sv.seq_num = self.sv.seq_num + 1
     end
 
@@ -75,9 +77,9 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
         local pkt = comms.mgmt_packet()
 
         pkt.make(msg_type, msg)
-        s_pkt.make(self.api.seq_num, PROTOCOL.SCADA_MGMT, pkt.raw_sendable())
+        s_pkt.make(self.api.addr, self.api.seq_num, PROTOCOL.SCADA_MGMT, pkt.raw_sendable())
 
-        modem.transmit(api_port, local_port, s_pkt.raw_sendable())
+        modem.transmit(crd_channel, pkt_channel, s_pkt.raw_sendable())
         self.api.seq_num = self.api.seq_num + 1
     end
 
@@ -89,9 +91,9 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
     --     local pkt = comms.capi_packet()
 
     --     pkt.make(msg_type, msg)
-    --     s_pkt.make(self.api.seq_num, PROTOCOL.COORD_API, pkt.raw_sendable())
+    --     s_pkt.make(self.api.addr, self.api.seq_num, PROTOCOL.COORD_API, pkt.raw_sendable())
 
-    --     modem.transmit(api_port, local_port, s_pkt.raw_sendable())
+    --     modem.transmit(crd_channel, pkt_channel, s_pkt.raw_sendable())
     --     self.api.seq_num = self.api.seq_num + 1
     -- end
 
@@ -133,6 +135,8 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
     function public.close_sv()
         sv_watchdog.cancel()
         self.sv.linked = false
+        self.sv.r_seq_num = nil
+        self.sv.addr = comms.BROADCAST
         _send_sv(SCADA_MGMT_TYPE.CLOSE, {})
     end
 
@@ -140,6 +144,8 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
     function public.close_api()
         api_watchdog.cancel()
         self.api.linked = false
+        self.api.r_seq_num = nil
+        self.api.addr = comms.BROADCAST
         _send_crd(SCADA_MGMT_TYPE.CLOSE, {})
     end
 
@@ -214,18 +220,23 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
     ---@param packet mgmt_frame|capi_frame|nil
     function public.handle_packet(packet)
         if packet ~= nil then
-            local l_port = packet.scada_frame.local_port()
-            local r_port = packet.scada_frame.remote_port()
+            local l_chan   = packet.scada_frame.local_channel()
+            local r_chan   = packet.scada_frame.remote_channel()
             local protocol = packet.scada_frame.protocol()
+            local src_addr = packet.scada_frame.src_addr()
 
-            if l_port ~= local_port then
-                log.debug("received packet on unconfigured channel " .. l_port, true)
-            elseif r_port == api_port then
+            if l_chan ~= pkt_channel then
+                log.debug("received packet on unconfigured channel " .. l_chan, true)
+            elseif r_chan == crd_channel then
                 -- check sequence number
                 if self.api.r_seq_num == nil then
                     self.api.r_seq_num = packet.scada_frame.seq_num()
                 elseif self.connected and ((self.api.r_seq_num + 1) ~= packet.scada_frame.seq_num()) then
-                    log.warning("sequence out-of-order: last = " .. self.api.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
+                    log.warning("sequence out-of-order (API): last = " .. self.api.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
+                    return
+                elseif self.api.linked and (src_addr ~= self.api.addr) then
+                    log.debug("received packet from unknown computer " .. src_addr .. " while linked (API expected " .. self.api.addr ..
+                                "); channel in use by another system?")
                     return
                 else
                     self.api.r_seq_num = packet.scada_frame.seq_num()
@@ -247,6 +258,7 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
                                 log.info("coordinator connection established")
                                 self.establish_delay_counter = 0
                                 self.api.linked = true
+                                self.api.addr = src_addr
 
                                 if self.sv.linked then
                                     coreio.report_link_state(LINK_STATE.LINKED)
@@ -294,6 +306,8 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
                             -- handle session close
                             api_watchdog.cancel()
                             self.api.linked = false
+                            self.api.r_seq_num = nil
+                            self.api.addr = comms.BROADCAST
                             log.info("coordinator server connection closed by remote host")
                         else
                             log.debug("received unknown SCADA_MGMT packet type " .. packet.type .. " from coordinator")
@@ -304,12 +318,16 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
                 else
                     log.debug("illegal packet type " .. protocol .. " from coordinator", true)
                 end
-            elseif r_port == sv_port then
+            elseif r_chan == svr_channel then
                 -- check sequence number
                 if self.sv.r_seq_num == nil then
                     self.sv.r_seq_num = packet.scada_frame.seq_num()
                 elseif self.connected and ((self.sv.r_seq_num + 1) ~= packet.scada_frame.seq_num()) then
-                    log.warning("sequence out-of-order: last = " .. self.sv.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
+                    log.warning("sequence out-of-order (SVR): last = " .. self.sv.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
+                    return
+                elseif self.sv.linked and (src_addr ~= self.sv.addr) then
+                    log.debug("received packet from unknown computer " .. src_addr .. " while linked (SVR expected " .. self.sv.addr ..
+                                "); channel in use by another system?")
                     return
                 else
                     self.sv.r_seq_num = packet.scada_frame.seq_num()
@@ -330,6 +348,7 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
                                 log.info("supervisor connection established")
                                 self.establish_delay_counter = 0
                                 self.sv.linked = true
+                                self.sv.addr = src_addr
 
                                 if self.api.linked then
                                     coreio.report_link_state(LINK_STATE.LINKED)
@@ -377,6 +396,8 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
                             -- handle session close
                             sv_watchdog.cancel()
                             self.sv.linked = false
+                            self.sv.r_seq_num = nil
+                            self.sv.addr = comms.BROADCAST
                             log.info("supervisor server connection closed by remote host")
                         else
                             log.debug("received unknown SCADA_MGMT packet type " .. packet.type .. " from supervisor")
@@ -388,7 +409,7 @@ function pocket.comms(version, modem, local_port, sv_port, api_port, range, sv_w
                     log.debug("illegal packet type " .. protocol .. " from supervisor", true)
                 end
             else
-                log.debug("received packet from unconfigured channel " .. r_port, true)
+                log.debug("received packet from unconfigured channel " .. r_chan, true)
             end
         end
     end
diff --git a/pocket/startup.lua b/pocket/startup.lua
index 075919d..0683af6 100644
--- a/pocket/startup.lua
+++ b/pocket/startup.lua
@@ -4,20 +4,20 @@
 
 require("/initenv").init_env()
 
-local crash        = require("scada-common.crash")
-local log          = require("scada-common.log")
-local ppm          = require("scada-common.ppm")
-local tcallbackdsp = require("scada-common.tcallbackdsp")
-local util         = require("scada-common.util")
+local crash    = require("scada-common.crash")
+local log      = require("scada-common.log")
+local ppm      = require("scada-common.ppm")
+local tcd      = require("scada-common.tcd")
+local util     = require("scada-common.util")
 
-local core         = require("graphics.core")
+local core     = require("graphics.core")
 
-local config       = require("pocket.config")
-local coreio       = require("pocket.coreio")
-local pocket       = require("pocket.pocket")
-local renderer     = require("pocket.renderer")
+local config   = require("pocket.config")
+local coreio   = require("pocket.coreio")
+local pocket   = require("pocket.pocket")
+local renderer = require("pocket.renderer")
 
-local POCKET_VERSION = "alpha-v0.3.2"
+local POCKET_VERSION = "alpha-v0.4.4"
 
 local println = util.println
 local println_ts = util.println_ts
@@ -28,9 +28,9 @@ local println_ts = util.println_ts
 
 local cfv = util.new_validator()
 
-cfv.assert_port(config.SCADA_SV_PORT)
-cfv.assert_port(config.SCADA_API_PORT)
-cfv.assert_port(config.LISTEN_PORT)
+cfv.assert_channel(config.SVR_CHANNEL)
+cfv.assert_channel(config.CRD_CHANNEL)
+cfv.assert_channel(config.PKT_CHANNEL)
 cfv.assert_type_int(config.TRUSTED_RANGE)
 cfv.assert_type_num(config.COMMS_TIMEOUT)
 cfv.assert_min(config.COMMS_TIMEOUT, 2)
@@ -89,8 +89,8 @@ local function main()
     log.debug("startup> conn watchdogs created")
 
     -- start comms, open all channels
-    local pocket_comms = pocket.comms(POCKET_VERSION, modem, config.LISTEN_PORT, config.SCADA_SV_PORT,
-                                        config.SCADA_API_PORT, config.TRUSTED_RANGE, conn_wd.sv, conn_wd.api)
+    local pocket_comms = pocket.comms(POCKET_VERSION, modem, config.PKT_CHANNEL, config.SVR_CHANNEL,
+                                        config.CRD_CHANNEL, config.TRUSTED_RANGE, conn_wd.sv, conn_wd.api)
     log.debug("startup> comms init")
 
     -- base loop clock (2Hz, 10 ticks)
@@ -120,54 +120,54 @@ local function main()
         conn_wd.sv.feed()
         conn_wd.api.feed()
         log.debug("startup> conn watchdog started")
-    end
 
-    -- main event loop
-    while ui_ok do
-        local event, param1, param2, param3, param4, param5 = util.pull_event()
+        -- main event loop
+        while true do
+            local event, param1, param2, param3, param4, param5 = util.pull_event()
 
-        -- handle event
-        if event == "timer" then
-            if loop_clock.is_clock(param1) then
-                -- main loop tick
+            -- handle event
+            if event == "timer" then
+                if loop_clock.is_clock(param1) then
+                    -- main loop tick
 
-                -- relink if necessary
-                pocket_comms.link_update()
+                    -- relink if necessary
+                    pocket_comms.link_update()
 
-                loop_clock.start()
-            elseif conn_wd.sv.is_timer(param1) then
-                -- supervisor watchdog timeout
-                log.info("supervisor server timeout")
-                pocket_comms.close_sv()
-            elseif conn_wd.api.is_timer(param1) then
-                -- coordinator watchdog timeout
-                log.info("coordinator api server timeout")
-                pocket_comms.close_api()
-            else
-                -- a non-clock/main watchdog timer event
-                -- notify timer callback dispatcher
-                tcallbackdsp.handle(param1)
+                    loop_clock.start()
+                elseif conn_wd.sv.is_timer(param1) then
+                    -- supervisor watchdog timeout
+                    log.info("supervisor server timeout")
+                    pocket_comms.close_sv()
+                elseif conn_wd.api.is_timer(param1) then
+                    -- coordinator watchdog timeout
+                    log.info("coordinator api server timeout")
+                    pocket_comms.close_api()
+                else
+                    -- a non-clock/main watchdog timer event
+                    -- notify timer callback dispatcher
+                    tcd.handle(param1)
+                end
+            elseif event == "modem_message" then
+                -- got a packet
+                local packet = pocket_comms.parse_packet(param1, param2, param3, param4, param5)
+                pocket_comms.handle_packet(packet)
+            elseif event == "mouse_click" or event == "mouse_up" or event == "mouse_drag" or event == "mouse_scroll" then
+                -- handle a monitor touch event
+                renderer.handle_mouse(core.events.new_mouse_event(event, param1, param2, param3))
+            end
+
+            -- check for termination request
+            if event == "terminate" or ppm.should_terminate() then
+                log.info("terminate requested, closing server connections...")
+                pocket_comms.close()
+                log.info("connections closed")
+                break
             end
-        elseif event == "modem_message" then
-            -- got a packet
-            local packet = pocket_comms.parse_packet(param1, param2, param3, param4, param5)
-            pocket_comms.handle_packet(packet)
-        elseif event == "mouse_click" or event == "mouse_up" or event == "mouse_drag" or event == "mouse_scroll" then
-            -- handle a monitor touch event
-            renderer.handle_mouse(core.events.new_mouse_event(event, param1, param2, param3))
         end
 
-        -- check for termination request
-        if event == "terminate" or ppm.should_terminate() then
-            log.info("terminate requested, closing server connections...")
-            pocket_comms.close()
-            log.info("connections closed")
-            break
-        end
+        renderer.close_ui()
     end
 
-    renderer.close_ui()
-
     println_ts("exited")
     log.info("exited")
 end
diff --git a/pocket/ui/components/conn_waiting.lua b/pocket/ui/components/conn_waiting.lua
index 9bbbfc0..114d165 100644
--- a/pocket/ui/components/conn_waiting.lua
+++ b/pocket/ui/components/conn_waiting.lua
@@ -25,7 +25,7 @@ local function init(parent, y, is_api)
     -- bounding box div
     local box = Div{parent=root,x=1,y=y,height=5}
 
-    local waiting_x = math.floor(parent.width() / 2) - 1
+    local waiting_x = math.floor(parent.get_width() / 2) - 1
 
     if is_api then
         WaitingAnim{parent=box,x=waiting_x,y=1,fg_bg=cpair(colors.blue,style.root.bkg)}
diff --git a/pocket/ui/main.lua b/pocket/ui/main.lua
index c143b0b..11331e4 100644
--- a/pocket/ui/main.lua
+++ b/pocket/ui/main.lua
@@ -8,11 +8,11 @@ local style        = require("pocket.ui.style")
 
 local conn_waiting = require("pocket.ui.components.conn_waiting")
 
-local home_page    = require("pocket.ui.components.home_page")
-local unit_page    = require("pocket.ui.components.unit_page")
-local reactor_page = require("pocket.ui.components.reactor_page")
-local boiler_page  = require("pocket.ui.components.boiler_page")
-local turbine_page = require("pocket.ui.components.turbine_page")
+local home_page    = require("pocket.ui.pages.home_page")
+local unit_page    = require("pocket.ui.pages.unit_page")
+local reactor_page = require("pocket.ui.pages.reactor_page")
+local boiler_page  = require("pocket.ui.pages.boiler_page")
+local turbine_page = require("pocket.ui.pages.turbine_page")
 
 local core         = require("graphics.core")
 
diff --git a/pocket/ui/components/boiler_page.lua b/pocket/ui/pages/boiler_page.lua
similarity index 100%
rename from pocket/ui/components/boiler_page.lua
rename to pocket/ui/pages/boiler_page.lua
diff --git a/pocket/ui/components/home_page.lua b/pocket/ui/pages/home_page.lua
similarity index 100%
rename from pocket/ui/components/home_page.lua
rename to pocket/ui/pages/home_page.lua
diff --git a/pocket/ui/components/reactor_page.lua b/pocket/ui/pages/reactor_page.lua
similarity index 100%
rename from pocket/ui/components/reactor_page.lua
rename to pocket/ui/pages/reactor_page.lua
diff --git a/pocket/ui/components/turbine_page.lua b/pocket/ui/pages/turbine_page.lua
similarity index 100%
rename from pocket/ui/components/turbine_page.lua
rename to pocket/ui/pages/turbine_page.lua
diff --git a/pocket/ui/components/unit_page.lua b/pocket/ui/pages/unit_page.lua
similarity index 100%
rename from pocket/ui/components/unit_page.lua
rename to pocket/ui/pages/unit_page.lua
diff --git a/reactor-plc/config.lua b/reactor-plc/config.lua
index e402bbb..3462b2c 100644
--- a/reactor-plc/config.lua
+++ b/reactor-plc/config.lua
@@ -9,10 +9,10 @@ config.REACTOR_ID = 1
 -- when emergency coolant is needed due to low coolant
 -- config.EMERGENCY_COOL = { side = "right", color = nil }
 
--- port to send packets TO server
-config.SERVER_PORT = 16000
--- port to listen to incoming packets FROM server
-config.LISTEN_PORT = 14001
+-- supervisor comms channel
+config.SVR_CHANNEL = 16240
+-- PLC comms channel
+config.PLC_CHANNEL = 16241
 -- max trusted modem message distance (0 to disable check)
 config.TRUSTED_RANGE = 0
 -- time in seconds (>= 2) before assuming a remote device is no longer active
diff --git a/reactor-plc/panel/front_panel.lua b/reactor-plc/panel/front_panel.lua
index 8e28a75..12c8266 100644
--- a/reactor-plc/panel/front_panel.lua
+++ b/reactor-plc/panel/front_panel.lua
@@ -2,6 +2,7 @@
 -- Main SCADA Coordinator GUI
 --
 
+local types      = require("scada-common.types")
 local util       = require("scada-common.util")
 
 local config     = require("reactor-plc.config")
@@ -49,7 +50,7 @@ local function init(panel)
     local reactor = LEDPair{parent=system,label="REACTOR",off=colors.red,c1=colors.yellow,c2=colors.green}
     local modem = LED{parent=system,label="MODEM",colors=cpair(colors.green,colors.green_off)}
     local network = RGBLED{parent=system,label="NETWORK",colors={colors.green,colors.red,colors.orange,colors.yellow,colors.gray}}
-    network.update(5)
+    network.update(types.PANEL_LINK_STATE.DISCONNECTED)
     system.line_break()
 
     reactor.register(databus.ps, "reactor_dev_state", reactor.update)
@@ -69,6 +70,10 @@ local function init(panel)
     rt_cmrx.register(databus.ps, "routine__comms_rx", rt_cmrx.update)
     rt_sctl.register(databus.ps, "routine__spctl", rt_sctl.update)
 
+---@diagnostic disable-next-line: undefined-field
+    local comp_id = util.sprintf("(%d)", os.getComputerID())
+    TextBox{parent=system,x=9,y=5,width=6,height=1,text=comp_id,fg_bg=cpair(colors.lightGray,colors.ivory)}
+
     --
     -- status & controls
     --
diff --git a/reactor-plc/plc.lua b/reactor-plc/plc.lua
index 4f04138..02e592a 100644
--- a/reactor-plc/plc.lua
+++ b/reactor-plc/plc.lua
@@ -446,14 +446,15 @@ end
 ---@param id integer reactor ID
 ---@param version string PLC version
 ---@param modem table modem device
----@param local_port integer local listening port
----@param server_port integer remote server port
+---@param plc_channel integer PLC comms channel
+---@param svr_channel integer supervisor server channel
 ---@param range integer trusted device connection range
 ---@param reactor table reactor device
 ---@param rps rps RPS reference
 ---@param conn_watchdog watchdog watchdog reference
-function plc.comms(id, version, modem, local_port, server_port, range, reactor, rps, conn_watchdog)
+function plc.comms(id, version, modem, plc_channel, svr_channel, range, reactor, rps, conn_watchdog)
     local self = {
+        sv_addr = comms.BROADCAST,
         seq_num = 0,
         r_seq_num = nil,
         scrammed = false,
@@ -472,7 +473,7 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
     -- configure modem channels
     local function _conf_channels()
         modem.closeAll()
-        modem.open(local_port)
+        modem.open(plc_channel)
     end
 
     _conf_channels()
@@ -485,9 +486,9 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
         local r_pkt = comms.rplc_packet()
 
         r_pkt.make(id, msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.RPLC, r_pkt.raw_sendable())
+        s_pkt.make(self.sv_addr, self.seq_num, PROTOCOL.RPLC, r_pkt.raw_sendable())
 
-        modem.transmit(server_port, local_port, s_pkt.raw_sendable())
+        modem.transmit(svr_channel, plc_channel, s_pkt.raw_sendable())
         self.seq_num = self.seq_num + 1
     end
 
@@ -499,9 +500,9 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(self.sv_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
-        modem.transmit(server_port, local_port, s_pkt.raw_sendable())
+        modem.transmit(svr_channel, plc_channel, s_pkt.raw_sendable())
         self.seq_num = self.seq_num + 1
     end
 
@@ -667,9 +668,11 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
 
     -- unlink from the server
     function public.unlink()
+        self.sv_addr = comms.BROADCAST
         self.linked = false
         self.r_seq_num = nil
         self.status_cache = nil
+        databus.tx_link_state(types.PANEL_LINK_STATE.DISCONNECTED)
     end
 
     -- close the connection to the server
@@ -731,7 +734,7 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
         end
     end
 
-    -- parse an RPLC packet
+    -- parse a packet
     ---@nodiscard
     ---@param side string
     ---@param sender integer
@@ -760,14 +763,14 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
                     pkt = mgmt_pkt.get()
                 end
             else
-                log.debug("illegal packet type " .. s_pkt.protocol(), true)
+                log.debug("unsupported packet type " .. s_pkt.protocol(), true)
             end
         end
 
         return pkt
     end
 
-    -- handle an RPLC packet
+    -- handle RPLC and MGMT packets
     ---@param packet rplc_frame|mgmt_frame packet frame
     ---@param plc_state plc_state PLC state
     ---@param setpoints setpoints setpoint control table
@@ -775,16 +778,22 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
         -- print a log message to the terminal as long as the UI isn't running
         local function println_ts(message) if not plc_state.fp_ok then util.println_ts(message) end end
 
-        local l_port = packet.scada_frame.local_port()
+        local protocol = packet.scada_frame.protocol()
+        local l_chan   = packet.scada_frame.local_channel()
+        local src_addr = packet.scada_frame.src_addr()
 
         -- handle packets now that we have prints setup
-        if l_port == local_port then
+        if l_chan == plc_channel then
             -- check sequence number
             if self.r_seq_num == nil then
                 self.r_seq_num = packet.scada_frame.seq_num()
             elseif self.linked and ((self.r_seq_num + 1) ~= packet.scada_frame.seq_num()) then
                 log.warning("sequence out-of-order: last = " .. self.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
                 return
+            elseif self.linked and (src_addr ~= self.sv_addr) then
+                log.debug("received packet from unknown computer " .. src_addr .. " while linked (expected " .. self.sv_addr ..
+                            "); channel in use by another system?")
+                return
             else
                 self.r_seq_num = packet.scada_frame.seq_num()
             end
@@ -792,11 +801,10 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
             -- feed the watchdog first so it doesn't uhh...eat our packets :)
             conn_watchdog.feed()
 
-            local protocol = packet.scada_frame.protocol()
-
             -- handle packet
             if protocol == PROTOCOL.RPLC then
                 ---@cast packet rplc_frame
+                -- if linked, only accept packets from configured supervisor
                 if self.linked then
                     if packet.type == RPLC_TYPE.STATUS then
                         -- request of full status, clear cache first
@@ -933,6 +941,7 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
                 end
             elseif protocol == PROTOCOL.SCADA_MGMT then
                 ---@cast packet mgmt_frame
+                -- if linked, only accept packets from configured supervisor
                 if self.linked then
                     if packet.type == SCADA_MGMT_TYPE.ESTABLISH then
                         -- link request confirmation
@@ -945,22 +954,26 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
                                 self.status_cache = nil
                                 _send_struct()
                                 public.send_status(plc_state.no_reactor, plc_state.reactor_formed)
-                                log.debug("re-sent initial status data")
-                            elseif est_ack == ESTABLISH_ACK.DENY then
-                                println_ts("received unsolicited link denial, unlinking")
-                                log.warning("unsolicited establish request denied")
-                            elseif est_ack == ESTABLISH_ACK.COLLISION then
-                                println_ts("received unsolicited link collision, unlinking")
-                                log.warning("unsolicited establish request collision")
-                            elseif est_ack == ESTABLISH_ACK.BAD_VERSION then
-                                println_ts("received unsolicited link version mismatch, unlinking")
-                                log.warning("unsolicited establish request version mismatch")
+                                log.debug("re-sent initial status data due to re-establish")
                             else
-                                println_ts("invalid unsolicited link response")
-                                log.debug("unsolicited unknown establish request response")
-                            end
+                                if est_ack == ESTABLISH_ACK.DENY then
+                                    println_ts("received unsolicited link denial, unlinking")
+                                    log.warning("unsolicited establish request denied")
+                                elseif est_ack == ESTABLISH_ACK.COLLISION then
+                                    println_ts("received unsolicited link collision, unlinking")
+                                    log.warning("unsolicited establish request collision")
+                                elseif est_ack == ESTABLISH_ACK.BAD_VERSION then
+                                    println_ts("received unsolicited link version mismatch, unlinking")
+                                    log.warning("unsolicited establish request version mismatch")
+                                else
+                                    println_ts("invalid unsolicited link response")
+                                    log.debug("unsolicited unknown establish request response")
+                                end
 
-                            self.linked = est_ack == ESTABLISH_ACK.ALLOW
+                                -- unlink
+                                self.sv_addr = comms.BROADCAST
+                                self.linked = false
+                            end
 
                             -- clear this since this is for something that was unsolicited
                             self.last_est_ack = ESTABLISH_ACK.ALLOW
@@ -980,7 +993,7 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
                                 log.warning("PLC KEEP_ALIVE trip time > 750ms (" .. trip_time .. "ms)")
                             end
 
-                            -- log.debug("RPLC RTT = " .. trip_time .. "ms")
+                            -- log.debug("PLC RTT = " .. trip_time .. "ms")
 
                             _send_keep_alive_ack(timestamp)
                         else
@@ -1002,9 +1015,11 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
 
                         if est_ack == ESTABLISH_ACK.ALLOW then
                             println_ts("linked!")
-                            log.info("supervisor establish request approved, PLC is linked")
+                            log.info("supervisor establish request approved, linked to SV (CID#" .. src_addr .. ")")
 
-                            -- reset remote sequence number and cache
+                            -- link + reset remote sequence number and cache
+                            self.sv_addr = src_addr
+                            self.linked = true
                             self.r_seq_num = nil
                             self.status_cache = nil
 
@@ -1012,23 +1027,28 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
                             public.send_status(plc_state.no_reactor, plc_state.reactor_formed)
 
                             log.debug("sent initial status data")
-                        elseif self.last_est_ack ~= est_ack then
-                            if est_ack == ESTABLISH_ACK.DENY then
-                                println_ts("link request denied, retrying...")
-                                log.info("supervisor establish request denied, retrying")
-                            elseif est_ack == ESTABLISH_ACK.COLLISION then
-                                println_ts("reactor PLC ID collision (check config), retrying...")
-                                log.warning("establish request collision, retrying")
-                            elseif est_ack == ESTABLISH_ACK.BAD_VERSION then
-                                println_ts("supervisor version mismatch (try updating), retrying...")
-                                log.warning("establish request version mismatch, retrying")
-                            else
-                                println_ts("invalid link response, bad channel? retrying...")
-                                log.error("unknown establish request response, retrying")
+                        else
+                            if self.last_est_ack ~= est_ack then
+                                if est_ack == ESTABLISH_ACK.DENY then
+                                    println_ts("link request denied, retrying...")
+                                    log.info("supervisor establish request denied, retrying")
+                                elseif est_ack == ESTABLISH_ACK.COLLISION then
+                                    println_ts("reactor PLC ID collision (check config), retrying...")
+                                    log.warning("establish request collision, retrying")
+                                elseif est_ack == ESTABLISH_ACK.BAD_VERSION then
+                                    println_ts("supervisor version mismatch (try updating), retrying...")
+                                    log.warning("establish request version mismatch, retrying")
+                                else
+                                    println_ts("invalid link response, bad channel? retrying...")
+                                    log.error("unknown establish request response, retrying")
+                                end
                             end
+
+                            -- unlink
+                            self.sv_addr = comms.BROADCAST
+                            self.linked = false
                         end
 
-                        self.linked = est_ack == ESTABLISH_ACK.ALLOW
                         self.last_est_ack = est_ack
 
                         -- report link state
@@ -1044,7 +1064,7 @@ function plc.comms(id, version, modem, local_port, server_port, range, reactor,
                 log.error("illegal packet type " .. protocol, true)
             end
         else
-            log.debug("received packet on unconfigured channel " .. l_port, true)
+            log.debug("received packet on unconfigured channel " .. l_chan, true)
         end
     end
 
diff --git a/reactor-plc/startup.lua b/reactor-plc/startup.lua
index 1a7f550..227bd27 100644
--- a/reactor-plc/startup.lua
+++ b/reactor-plc/startup.lua
@@ -18,7 +18,7 @@ local plc      = require("reactor-plc.plc")
 local renderer = require("reactor-plc.renderer")
 local threads  = require("reactor-plc.threads")
 
-local R_PLC_VERSION = "v1.3.2"
+local R_PLC_VERSION = "v1.4.5"
 
 local println = util.println
 local println_ts = util.println_ts
@@ -31,8 +31,8 @@ local cfv = util.new_validator()
 
 cfv.assert_type_bool(config.NETWORKED)
 cfv.assert_type_int(config.REACTOR_ID)
-cfv.assert_port(config.SERVER_PORT)
-cfv.assert_port(config.LISTEN_PORT)
+cfv.assert_channel(config.SVR_CHANNEL)
+cfv.assert_channel(config.PLC_CHANNEL)
 cfv.assert_type_int(config.TRUSTED_RANGE)
 cfv.assert_type_num(config.COMMS_TIMEOUT)
 cfv.assert_min(config.COMMS_TIMEOUT, 2)
@@ -197,7 +197,7 @@ local function main()
                 log.debug("init> conn watchdog started")
 
                 -- start comms
-                smem_sys.plc_comms = plc.comms(config.REACTOR_ID, R_PLC_VERSION, smem_dev.modem, config.LISTEN_PORT, config.SERVER_PORT,
+                smem_sys.plc_comms = plc.comms(config.REACTOR_ID, R_PLC_VERSION, smem_dev.modem, config.PLC_CHANNEL, config.SVR_CHANNEL,
                                                 config.TRUSTED_RANGE, smem_dev.reactor, smem_sys.rps, smem_sys.conn_watchdog)
                 log.debug("init> comms init")
             else
diff --git a/reactor-plc/threads.lua b/reactor-plc/threads.lua
index 8dbea6d..b9c986d 100644
--- a/reactor-plc/threads.lua
+++ b/reactor-plc/threads.lua
@@ -1,13 +1,13 @@
-local log          = require("scada-common.log")
-local mqueue       = require("scada-common.mqueue")
-local ppm          = require("scada-common.ppm")
-local tcallbackdsp = require("scada-common.tcallbackdsp")
-local util         = require("scada-common.util")
+local log      = require("scada-common.log")
+local mqueue   = require("scada-common.mqueue")
+local ppm      = require("scada-common.ppm")
+local tcd      = require("scada-common.tcd")
+local util     = require("scada-common.util")
 
-local databus      = require("reactor-plc.databus")
-local renderer     = require("reactor-plc.renderer")
+local databus  = require("reactor-plc.databus")
+local renderer = require("reactor-plc.renderer")
 
-local core         = require("graphics.core")
+local core     = require("graphics.core")
 
 local threads = {}
 
@@ -157,7 +157,7 @@ function threads.thread__main(smem, init)
                 smem.q.mq_rps.push_command(MQ__RPS_CMD.TRIP_TIMEOUT)
             elseif event == "timer" then
                 -- notify timer callback dispatcher if no other timer case claimed this event
-                tcallbackdsp.handle(param1)
+                tcd.handle(param1)
             elseif event == "peripheral_detach" then
                 -- peripheral disconnect
                 local type, device = ppm.handle_unmount(param1)
diff --git a/rtu/config.lua b/rtu/config.lua
index 1b96bec..2279759 100644
--- a/rtu/config.lua
+++ b/rtu/config.lua
@@ -2,11 +2,11 @@ local rsio = require("scada-common.rsio")
 
 local config = {}
 
--- port to send packets TO server
-config.SERVER_PORT = 16000
--- port to listen to incoming packets FROM server
-config.LISTEN_PORT = 15001
--- max trusted modem message distance (< 1 to disable check)
+-- supervisor comms channel
+config.SVR_CHANNEL = 16240
+-- RTU/MODBUS comms channel
+config.RTU_CHANNEL = 16242
+-- max trusted modem message distance (0 to disable check)
 config.TRUSTED_RANGE = 0
 -- time in seconds (>= 2) before assuming a remote device is no longer active
 config.COMMS_TIMEOUT = 5
diff --git a/rtu/panel/front_panel.lua b/rtu/panel/front_panel.lua
index 4c4aa78..467386e 100644
--- a/rtu/panel/front_panel.lua
+++ b/rtu/panel/front_panel.lua
@@ -2,6 +2,7 @@
 -- Main SCADA Coordinator GUI
 --
 
+local types      = require("scada-common.types")
 local util       = require("scada-common.util")
 
 local databus    = require("rtu.databus")
@@ -44,7 +45,7 @@ local function init(panel, units)
 
     local system = Div{parent=panel,width=14,height=18,x=2,y=3}
 
-    local on = LED{parent=system,label="POWER",colors=cpair(colors.green,colors.red)}
+    local on = LED{parent=system,label="STATUS",colors=cpair(colors.green,colors.red)}
     local heartbeat = LED{parent=system,label="HEARTBEAT",colors=cpair(colors.green,colors.green_off)}
     on.update(true)
     system.line_break()
@@ -53,7 +54,7 @@ local function init(panel, units)
 
     local modem = LED{parent=system,label="MODEM",colors=cpair(colors.green,colors.green_off)}
     local network = RGBLED{parent=system,label="NETWORK",colors={colors.green,colors.red,colors.orange,colors.yellow,colors.gray}}
-    network.update(5)
+    network.update(types.PANEL_LINK_STATE.DISCONNECTED)
     system.line_break()
 
     modem.register(databus.ps, "has_modem", modem.update)
@@ -66,6 +67,10 @@ local function init(panel, units)
     rt_main.register(databus.ps, "routine__main", rt_main.update)
     rt_comm.register(databus.ps, "routine__comms", rt_comm.update)
 
+---@diagnostic disable-next-line: undefined-field
+    local comp_id = util.sprintf("(%d)", os.getComputerID())
+    TextBox{parent=system,x=9,y=4,width=6,height=1,text=comp_id,fg_bg=cpair(colors.lightGray,colors.ivory)}
+
     --
     -- about label
     --
diff --git a/rtu/rtu.lua b/rtu/rtu.lua
index bb43706..831e231 100644
--- a/rtu/rtu.lua
+++ b/rtu/rtu.lua
@@ -159,12 +159,13 @@ end
 ---@nodiscard
 ---@param version string RTU version
 ---@param modem table modem device
----@param local_port integer local listening port
----@param server_port integer remote server port
+---@param rtu_channel integer PLC comms channel
+---@param svr_channel integer supervisor server channel
 ---@param range integer trusted device connection range
 ---@param conn_watchdog watchdog watchdog reference
-function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog)
+function rtu.comms(version, modem, rtu_channel, svr_channel, range, conn_watchdog)
     local self = {
+        sv_addr = comms.BROADCAST,
         seq_num = 0,
         r_seq_num = nil,
         txn_id = 0,
@@ -180,7 +181,7 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
     -- configure modem channels
     local function _conf_channels()
         modem.closeAll()
-        modem.open(local_port)
+        modem.open(rtu_channel)
     end
 
     _conf_channels()
@@ -193,9 +194,9 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(self.sv_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
-        modem.transmit(server_port, local_port, s_pkt.raw_sendable())
+        modem.transmit(svr_channel, rtu_channel, s_pkt.raw_sendable())
         self.seq_num = self.seq_num + 1
     end
 
@@ -238,8 +239,8 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
     ---@param m_pkt modbus_packet
     function public.send_modbus(m_pkt)
         local s_pkt = comms.scada_packet()
-        s_pkt.make(self.seq_num, PROTOCOL.MODBUS_TCP, m_pkt.raw_sendable())
-        modem.transmit(server_port, local_port, s_pkt.raw_sendable())
+        s_pkt.make(self.sv_addr, self.seq_num, PROTOCOL.MODBUS_TCP, m_pkt.raw_sendable())
+        modem.transmit(svr_channel, rtu_channel, s_pkt.raw_sendable())
         self.seq_num = self.seq_num + 1
     end
 
@@ -254,7 +255,9 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
     ---@param rtu_state rtu_state
     function public.unlink(rtu_state)
         rtu_state.linked = false
+        self.sv_addr = comms.BROADCAST
         self.r_seq_num = nil
+        databus.tx_link_state(types.PANEL_LINK_STATE.DISCONNECTED)
     end
 
     -- close the connection to the server
@@ -327,13 +330,21 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
         -- print a log message to the terminal as long as the UI isn't running
         local function println_ts(message) if not rtu_state.fp_ok then util.println_ts(message) end end
 
-        if packet.scada_frame.local_port() == local_port then
+        local protocol = packet.scada_frame.protocol()
+        local l_chan   = packet.scada_frame.local_channel()
+        local src_addr = packet.scada_frame.src_addr()
+
+        if l_chan == rtu_channel then
             -- check sequence number
             if self.r_seq_num == nil then
                 self.r_seq_num = packet.scada_frame.seq_num()
             elseif rtu_state.linked and ((self.r_seq_num + 1) ~= packet.scada_frame.seq_num()) then
                 log.warning("sequence out-of-order: last = " .. self.r_seq_num .. ", new = " .. packet.scada_frame.seq_num())
                 return
+            elseif rtu_state.linked and (src_addr ~= self.sv_addr) then
+                log.debug("received packet from unknown computer " .. src_addr .. " while linked (expected " .. self.sv_addr ..
+                            "); channel in use by another system?")
+                return
             else
                 self.r_seq_num = packet.scada_frame.seq_num()
             end
@@ -341,8 +352,7 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
             -- feed watchdog on valid sequence number
             conn_watchdog.feed()
 
-            local protocol = packet.scada_frame.protocol()
-
+            -- handle packet
             if protocol == PROTOCOL.MODBUS_TCP then
                 ---@cast packet modbus_frame
                 if rtu_state.linked then
@@ -398,6 +408,7 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
                         if est_ack == ESTABLISH_ACK.ALLOW then
                             -- establish allowed
                             rtu_state.linked = true
+                            self.sv_addr = packet.scada_frame.src_addr()
                             self.r_seq_num = nil
                             println_ts("supervisor connection established")
                             log.info("supervisor connection established")
@@ -461,6 +472,8 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
                 -- should be unreachable assuming packet is from parse_packet()
                 log.error("illegal packet type " .. protocol, true)
             end
+        else
+            log.debug("received packet on unconfigured channel " .. l_chan, true)
         end
     end
 
diff --git a/rtu/startup.lua b/rtu/startup.lua
index 6ff5e7d..05b131b 100644
--- a/rtu/startup.lua
+++ b/rtu/startup.lua
@@ -28,7 +28,7 @@ local sna_rtu      = require("rtu.dev.sna_rtu")
 local sps_rtu      = require("rtu.dev.sps_rtu")
 local turbinev_rtu = require("rtu.dev.turbinev_rtu")
 
-local RTU_VERSION = "v1.2.2"
+local RTU_VERSION = "v1.3.5"
 
 local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 local RTU_UNIT_HW_STATE = databus.RTU_UNIT_HW_STATE
@@ -42,8 +42,8 @@ local println_ts = util.println_ts
 
 local cfv = util.new_validator()
 
-cfv.assert_port(config.SERVER_PORT)
-cfv.assert_port(config.LISTEN_PORT)
+cfv.assert_channel(config.SVR_CHANNEL)
+cfv.assert_channel(config.RTU_CHANNEL)
 cfv.assert_type_int(config.TRUSTED_RANGE)
 cfv.assert_type_num(config.COMMS_TIMEOUT)
 cfv.assert_min(config.COMMS_TIMEOUT, 2)
@@ -457,9 +457,9 @@ local function main()
         if not rtu_state.fp_ok then
             renderer.close_ui()
             println_ts(util.c("UI error: ", message))
-            println("init> running without front panel")
+            println("startup> running without front panel")
             log.error(util.c("GUI crashed with error ", message))
-            log.info("init> running in headless mode without front panel")
+            log.info("startup> running in headless mode without front panel")
         end
 
         -- start connection watchdog
@@ -467,7 +467,7 @@ local function main()
         log.debug("startup> conn watchdog started")
 
         -- setup comms
-        smem_sys.rtu_comms = rtu.comms(RTU_VERSION, smem_dev.modem, config.LISTEN_PORT, config.SERVER_PORT,
+        smem_sys.rtu_comms = rtu.comms(RTU_VERSION, smem_dev.modem, config.RTU_CHANNEL, config.SVR_CHANNEL,
                                         config.TRUSTED_RANGE, smem_sys.conn_watchdog)
         log.debug("startup> comms init")
 
diff --git a/rtu/threads.lua b/rtu/threads.lua
index 046525c..fdb82b3 100644
--- a/rtu/threads.lua
+++ b/rtu/threads.lua
@@ -1,6 +1,7 @@
 local log          = require("scada-common.log")
 local mqueue       = require("scada-common.mqueue")
 local ppm          = require("scada-common.ppm")
+local tcd          = require("scada-common.tcd")
 local types        = require("scada-common.types")
 local util         = require("scada-common.util")
 
@@ -82,6 +83,9 @@ function threads.thread__main(smem)
             elseif event == "timer" and conn_watchdog.is_timer(param1) then
                 -- haven't heard from server recently? unlink
                 rtu_comms.unlink(rtu_state)
+            elseif event == "timer" then
+                -- notify timer callback dispatcher if no other timer case claimed this event
+                tcd.handle(param1)
             elseif event == "peripheral_detach" then
                 -- handle loss of a device
                 local type, device = ppm.handle_unmount(param1)
diff --git a/scada-common/comms.lua b/scada-common/comms.lua
index fb54101..c5e9fd2 100644
--- a/scada-common/comms.lua
+++ b/scada-common/comms.lua
@@ -4,14 +4,17 @@
 
 local log = require("scada-common.log")
 
+local insert = table.insert
+
+---@diagnostic disable-next-line: undefined-field
+local C_ID = os.getComputerID() ---@type integer computer ID
+
+local max_distance = nil        ---@type number|nil maximum acceptable transmission distance
+
 ---@class comms
 local comms = {}
 
-local insert = table.insert
-
-local max_distance = nil
-
-comms.version = "1.4.1"
+comms.version = "2.0.0"
 
 ---@enum PROTOCOL
 local PROTOCOL = {
@@ -122,27 +125,28 @@ comms.PLC_AUTO_ACK = PLC_AUTO_ACK
 comms.UNIT_COMMAND = UNIT_COMMAND
 comms.FAC_COMMAND = FAC_COMMAND
 
+-- destination broadcast address (to all devices)
+comms.BROADCAST = -1
+
 ---@alias packet scada_packet|modbus_packet|rplc_packet|mgmt_packet|crdn_packet|capi_packet
 ---@alias frame modbus_frame|rplc_frame|mgmt_frame|crdn_frame|capi_frame
 
 -- configure the maximum allowable message receive distance<br>
 -- packets received with distances greater than this will be silently discarded
----@param distance integer max modem message distance (less than 1 disables the limit)
+---@param distance integer max modem message distance (0 disables the limit)
 function comms.set_trusted_range(distance)
-    if distance < 1 then
-        max_distance = nil
-    else
-        max_distance = distance
-    end
+    if distance == 0 then max_distance = nil else max_distance = distance end
 end
 
 -- generic SCADA packet object
 ---@nodiscard
 function comms.scada_packet()
     local self = {
-        modem_msg_in = nil,
+        modem_msg_in = nil, ---@type modem_message|nil
         valid = false,
-        raw = { -1, PROTOCOL.SCADA_MGMT, {} },
+        raw = {},
+        src_addr = comms.BROADCAST,
+        dest_addr = comms.BROADCAST,
         seq_num = -1,
         protocol = PROTOCOL.SCADA_MGMT,
         length = 0,
@@ -153,34 +157,40 @@ function comms.scada_packet()
     local public = {}
 
     -- make a SCADA packet
-    ---@param seq_num integer
+    ---@param dest_addr integer destination computer address (ID)
+    ---@param seq_num integer sequence number
     ---@param protocol PROTOCOL
     ---@param payload table
-    function public.make(seq_num, protocol, payload)
+    function public.make(dest_addr, seq_num, protocol, payload)
         self.valid = true
+---@diagnostic disable-next-line: undefined-field
+        self.src_addr = C_ID
+        self.dest_addr = dest_addr
         self.seq_num = seq_num
         self.protocol = protocol
         self.length = #payload
         self.payload = payload
-        self.raw = { self.seq_num, self.protocol, self.payload }
+        self.raw = { self.src_addr, self.dest_addr, self.seq_num, self.protocol, self.payload }
     end
 
     -- parse in a modem message as a SCADA packet
     ---@param side string modem side
-    ---@param sender integer sender port
-    ---@param reply_to integer reply port
+    ---@param sender integer sender channel
+    ---@param reply_to integer reply channel
     ---@param message any message body
     ---@param distance integer transmission distance
     ---@return boolean valid valid message received
     function public.receive(side, sender, reply_to, message, distance)
+        ---@class modem_message
         self.modem_msg_in = {
             iface = side,
-            s_port = sender,
-            r_port = reply_to,
+            s_channel = sender,
+            r_channel = reply_to,
             msg = message,
             dist = distance
         }
 
+        self.valid = false
         self.raw = self.modem_msg_in.msg
 
         if (type(max_distance) == "number") and (distance > max_distance) then
@@ -188,20 +198,31 @@ function comms.scada_packet()
             -- log.debug("comms.scada_packet.receive(): discarding packet with distance " .. distance .. " outside of trusted range")
         else
             if type(self.raw) == "table" then
-                if #self.raw >= 3 then
-                    self.seq_num = self.raw[1]
-                    self.protocol = self.raw[2]
+                if #self.raw == 5 then
+                    self.src_addr = self.raw[1]
+                    self.dest_addr = self.raw[2]
+                    self.seq_num = self.raw[3]
+                    self.protocol = self.raw[4]
 
-                    -- element 3 must be a table
-                    if type(self.raw[3]) == "table" then
-                        self.length = #self.raw[3]
-                        self.payload = self.raw[3]
+                    -- element 5 must be a table
+                    if type(self.raw[5]) == "table" then
+                        self.length = #self.raw[5]
+                        self.payload = self.raw[5]
                     end
+                else
+                    self.src_addr = nil
+                    self.dest_addr = nil
+                    self.seq_num = nil
+                    self.protocol = nil
+                    self.length = 0
+                    self.payload = {}
                 end
 
-                self.valid = type(self.seq_num) == "number" and
-                             type(self.protocol) == "number" and
-                             type(self.payload) == "table"
+                -- check if this packet is destined for this device
+                local is_destination = (self.dest_addr == comms.BROADCAST) or (self.dest_addr == C_ID)
+
+                self.valid = is_destination and type(self.src_addr) == "number" and type(self.dest_addr) == "number" and
+                             type(self.seq_num) == "number" and type(self.protocol) == "number" and type(self.payload) == "table"
             end
         end
 
@@ -216,13 +237,17 @@ function comms.scada_packet()
     function public.raw_sendable() return self.raw end
 
     ---@nodiscard
-    function public.local_port() return self.modem_msg_in.s_port end
+    function public.local_channel() return self.modem_msg_in.s_channel end
     ---@nodiscard
-    function public.remote_port() return self.modem_msg_in.r_port end
+    function public.remote_channel() return self.modem_msg_in.r_channel end
 
     ---@nodiscard
     function public.is_valid() return self.valid end
 
+    ---@nodiscard
+    function public.src_addr() return self.src_addr end
+    ---@nodiscard
+    function public.dest_addr() return self.dest_addr end
     ---@nodiscard
     function public.seq_num() return self.seq_num end
     ---@nodiscard
diff --git a/scada-common/tcallbackdsp.lua b/scada-common/tcd.lua
similarity index 91%
rename from scada-common/tcallbackdsp.lua
rename to scada-common/tcd.lua
index 3f8f07a..f5ff0e5 100644
--- a/scada-common/tcallbackdsp.lua
+++ b/scada-common/tcd.lua
@@ -5,14 +5,14 @@
 local log  = require("scada-common.log")
 local util = require("scada-common.util")
 
-local tcallbackdsp = {}
+local tcd = {}
 
 local registry = {}
 
 -- request a function to be called after the specified time
 ---@param time number seconds
 ---@param f function callback function
-function tcallbackdsp.dispatch(time, f)
+function tcd.dispatch(time, f)
     local timer = util.start_timer(time)
     registry[timer] = {
         callback = f,
@@ -24,7 +24,7 @@ end
 -- request a function to be called after the specified time, aborting any registered instances of that function reference
 ---@param time number seconds
 ---@param f function callback function
-function tcallbackdsp.dispatch_unique(time, f)
+function tcd.dispatch_unique(time, f)
     -- cancel if already registered
     for timer, entry in pairs(registry) do
         if entry.callback == f then
@@ -47,7 +47,7 @@ end
 
 -- abort a requested callback
 ---@param f function callback function
-function tcallbackdsp.abort(f)
+function tcd.abort(f)
     for timer, entry in pairs(registry) do
         if entry.callback == f then
             -- cancel event and remove from registry (even if it fires it won't call)
@@ -59,7 +59,7 @@ end
 
 -- lookup a timer event and execute the callback if found
 ---@param event integer timer event timer ID
-function tcallbackdsp.handle(event)
+function tcd.handle(event)
     if registry[event] ~= nil then
         local callback = registry[event].callback
         -- clear first so that dispatch_unique call from inside callback won't throw a debug message
@@ -70,7 +70,7 @@ end
 
 -- identify any overdo callbacks<br>
 -- prints to log debug output
-function tcallbackdsp.diagnostics()
+function tcd.diagnostics()
     for timer, entry in pairs(registry) do
         if entry.expiry < util.time_s() then
             local overtime = util.time_s() - entry.expiry
@@ -82,4 +82,4 @@ function tcallbackdsp.diagnostics()
     end
 end
 
-return tcallbackdsp
+return tcd
diff --git a/scada-common/types.lua b/scada-common/types.lua
index 8df01c1..21429b5 100644
--- a/scada-common/types.lua
+++ b/scada-common/types.lua
@@ -74,6 +74,15 @@ function types.new_zero_coordinate() return { x = 0, y = 0, z = 0 } end
 -- ENUMERATION TYPES --
 --#region
 
+---@enum PANEL_LINK_STATE
+types.PANEL_LINK_STATE = {
+    LINKED = 1,
+    DENIED = 2,
+    COLLISION = 3,
+    BAD_VERSION = 4,
+    DISCONNECTED = 5
+}
+
 ---@enum RTU_UNIT_TYPE
 types.RTU_UNIT_TYPE = {
     VIRTUAL = 0,        -- virtual device
diff --git a/scada-common/util.lua b/scada-common/util.lua
index 063143c..99f62a6 100644
--- a/scada-common/util.lua
+++ b/scada-common/util.lua
@@ -65,7 +65,8 @@ end
 ---@return string
 function util.strval(val)
     local t = type(val)
-    if t == "table" or t == "function" then
+    -- this depends on Lua short-circuiting the or check for metatables (note: metatables won't have metatables)
+    if (t == "table" and (getmetatable(val) == nil or getmetatable(val).__tostring == nil)) or t == "function" then
         return "[" .. tostring(val) .. "]"
     else
         return tostring(val)
@@ -539,7 +540,7 @@ function util.new_validator()
     function public.assert_range(check, min, max) valid = valid and check >= min and check <= max end
     function public.assert_range_ex(check, min, max) valid = valid and check > min and check < max end
 
-    function public.assert_port(port) valid = valid and type(port) == "number" and port >= 0 and port <= 65535 end
+    function public.assert_channel(channel) valid = valid and type(channel) == "number" and channel >= 0 and channel <= 65535 end
 
     -- check if all assertions passed successfully
     ---@nodiscard
diff --git a/supervisor/config.lua b/supervisor/config.lua
index b716d38..a4a595b 100644
--- a/supervisor/config.lua
+++ b/supervisor/config.lua
@@ -1,9 +1,15 @@
 local config = {}
 
--- scada network listen for PLC's and RTU's
-config.SCADA_DEV_LISTEN = 16000
--- listen port for SCADA supervisor access
-config.SCADA_SV_CTL_LISTEN = 16100
+-- supervisor comms channel
+config.SVR_CHANNEL = 16240
+-- PLC comms channel
+config.PLC_CHANNEL = 16241
+-- RTU/MODBUS comms channel
+config.RTU_CHANNEL = 16242
+-- coordinator comms channel
+config.CRD_CHANNEL = 16243
+-- pocket comms channel
+config.PKT_CHANNEL = 16244
 -- max trusted modem message distance (0 to disable check)
 config.TRUSTED_RANGE = 0
 -- time in seconds (>= 2) before assuming a remote device is no longer active
diff --git a/supervisor/databus.lua b/supervisor/databus.lua
new file mode 100644
index 0000000..00185c7
--- /dev/null
+++ b/supervisor/databus.lua
@@ -0,0 +1,179 @@
+--
+-- Data Bus - Central Communication Linking for Supervisor Front Panel
+--
+
+local psil = require("scada-common.psil")
+local util = require("scada-common.util")
+
+local pgi  = require("supervisor.panel.pgi")
+
+-- nominal RTT is ping (0ms to 10ms usually) + 150ms for SV main loop tick
+local WARN_RTT = 300    -- 2x as long as expected w/ 0 ping
+local HIGH_RTT = 500    -- 3.33x as long as expected w/ 0 ping
+
+local databus = {}
+
+-- databus PSIL
+databus.ps = psil.create()
+
+-- call to toggle heartbeat signal
+function databus.heartbeat() databus.ps.toggle("heartbeat") end
+
+-- transmit firmware versions across the bus
+---@param sv_v string supervisor version
+---@param comms_v string comms version
+function databus.tx_versions(sv_v, comms_v)
+    databus.ps.publish("version", sv_v)
+    databus.ps.publish("comms_version", comms_v)
+end
+
+-- transmit hardware status for modem connection state
+---@param has_modem boolean
+function databus.tx_hw_modem(has_modem)
+    databus.ps.publish("has_modem", has_modem)
+end
+
+-- transmit PLC firmware version and session connection state
+---@param reactor_id integer reactor unit ID
+---@param fw string firmware version
+---@param s_addr integer PLC computer ID
+function databus.tx_plc_connected(reactor_id, fw, s_addr)
+    databus.ps.publish("plc_" .. reactor_id .. "_fw", fw)
+    databus.ps.publish("plc_" .. reactor_id .. "_conn", true)
+    databus.ps.publish("plc_" .. reactor_id .. "_addr", util.sprintf("@% 4d", s_addr))
+end
+
+-- transmit PLC disconnected
+---@param reactor_id integer reactor unit ID
+function databus.tx_plc_disconnected(reactor_id)
+    databus.ps.publish("plc_" .. reactor_id .. "_fw", " ------- ")
+    databus.ps.publish("plc_" .. reactor_id .. "_conn", false)
+    databus.ps.publish("plc_" .. reactor_id .. "_addr", " --- ")
+    databus.ps.publish("plc_" .. reactor_id .. "_rtt", 0)
+    databus.ps.publish("plc_" .. reactor_id .. "_rtt_color", colors.lightGray)
+end
+
+-- transmit PLC session RTT
+---@param reactor_id integer reactor unit ID
+---@param rtt integer round trip time
+function databus.tx_plc_rtt(reactor_id, rtt)
+    databus.ps.publish("plc_" .. reactor_id .. "_rtt", rtt)
+
+    if rtt > HIGH_RTT then
+        databus.ps.publish("plc_" .. reactor_id .. "_rtt_color", colors.red)
+    elseif rtt > WARN_RTT then
+        databus.ps.publish("plc_" .. reactor_id .. "_rtt_color", colors.yellow_hc)
+    else
+        databus.ps.publish("plc_" .. reactor_id .. "_rtt_color", colors.green)
+    end
+end
+
+-- transmit RTU firmware version and session connection state
+---@param session_id integer RTU session
+---@param fw string firmware version
+---@param s_addr integer RTU computer ID
+function databus.tx_rtu_connected(session_id, fw, s_addr)
+    databus.ps.publish("rtu_" .. session_id .. "_fw", fw)
+    databus.ps.publish("rtu_" .. session_id .. "_addr", util.sprintf("@ C% 3d", s_addr))
+    pgi.create_rtu_entry(session_id)
+end
+
+-- transmit RTU disconnected
+---@param session_id integer RTU session
+function databus.tx_rtu_disconnected(session_id)
+    pgi.delete_rtu_entry(session_id)
+end
+
+-- transmit RTU session RTT
+---@param session_id integer RTU session
+---@param rtt integer round trip time
+function databus.tx_rtu_rtt(session_id, rtt)
+    databus.ps.publish("rtu_" .. session_id .. "_rtt", rtt)
+
+    if rtt > HIGH_RTT then
+        databus.ps.publish("rtu_" .. session_id .. "_rtt_color", colors.red)
+    elseif rtt > WARN_RTT then
+        databus.ps.publish("rtu_" .. session_id .. "_rtt_color", colors.yellow_hc)
+    else
+        databus.ps.publish("rtu_" .. session_id .. "_rtt_color", colors.green)
+    end
+end
+
+-- transmit RTU session unit count
+---@param session_id integer RTU session
+---@param units integer unit count
+function databus.tx_rtu_units(session_id, units)
+    databus.ps.publish("rtu_" .. session_id .. "_units", units)
+end
+
+-- transmit coordinator firmware version and session connection state
+---@param fw string firmware version
+---@param s_addr integer coordinator computer ID
+function databus.tx_crd_connected(fw, s_addr)
+    databus.ps.publish("crd_fw", fw)
+    databus.ps.publish("crd_conn", true)
+    databus.ps.publish("crd_addr", tostring(s_addr))
+end
+
+-- transmit coordinator disconnected
+function databus.tx_crd_disconnected()
+    databus.ps.publish("crd_fw", " ------- ")
+    databus.ps.publish("crd_conn", false)
+    databus.ps.publish("crd_addr", "---")
+    databus.ps.publish("crd_rtt", 0)
+    databus.ps.publish("crd_rtt_color", colors.lightGray)
+end
+
+-- transmit coordinator session RTT
+---@param rtt integer round trip time
+function databus.tx_crd_rtt(rtt)
+    databus.ps.publish("crd_rtt", rtt)
+
+    if rtt > HIGH_RTT then
+        databus.ps.publish("crd_rtt_color", colors.red)
+    elseif rtt > WARN_RTT then
+        databus.ps.publish("crd_rtt_color", colors.yellow_hc)
+    else
+        databus.ps.publish("crd_rtt_color", colors.green)
+    end
+end
+
+-- transmit PKT firmware version and PDG session connection state
+---@param session_id integer PDG session
+---@param fw string firmware version
+---@param s_addr integer PDG computer ID
+function databus.tx_pdg_connected(session_id, fw, s_addr)
+    databus.ps.publish("pdg_" .. session_id .. "_fw", fw)
+    databus.ps.publish("pdg_" .. session_id .. "_addr", util.sprintf("@ C% 3d", s_addr))
+    pgi.create_pdg_entry(session_id)
+end
+
+-- transmit PDG session disconnected
+---@param session_id integer PDG session
+function databus.tx_pdg_disconnected(session_id)
+    pgi.delete_pdg_entry(session_id)
+end
+
+-- transmit PDG session RTT
+---@param session_id integer PDG session
+---@param rtt integer round trip time
+function databus.tx_pdg_rtt(session_id, rtt)
+    databus.ps.publish("pdg_" .. session_id .. "_rtt", rtt)
+
+    if rtt > HIGH_RTT then
+        databus.ps.publish("pdg_" .. session_id .. "_rtt_color", colors.red)
+    elseif rtt > WARN_RTT then
+        databus.ps.publish("pdg_" .. session_id .. "_rtt_color", colors.yellow_hc)
+    else
+        databus.ps.publish("pdg_" .. session_id .. "_rtt_color", colors.green)
+    end
+end
+
+-- link a function to receive data from the bus
+---@param field string field name
+---@param func function function to link
+function databus.rx_field(field, func)
+    databus.ps.subscribe(field, func)
+end
+
+return databus
diff --git a/supervisor/facility.lua b/supervisor/facility.lua
index f37de26..e3b8059 100644
--- a/supervisor/facility.lua
+++ b/supervisor/facility.lua
@@ -128,7 +128,7 @@ function facility.new(num_reactors, cooling_conf)
         for i = 1, #self.prio_defs do
             local units = self.prio_defs[i]
             for u = 1, #units do
-                all_ramped = all_ramped and units[u].a_ramp_complete()
+                all_ramped = all_ramped and units[u].auto_ramp_complete()
             end
         end
 
@@ -159,7 +159,7 @@ function facility.new(num_reactors, cooling_conf)
                     local u = units[id] ---@type reactor_unit
 
                     local ctl = u.get_control_inf()
-                    local lim_br100 = u.a_get_effective_limit()
+                    local lim_br100 = u.auto_get_effective_limit()
 
                     if abort_on_fault and (lim_br100 ~= ctl.lim_br100) then
                         -- effective limit differs from set limit, unit is degraded
@@ -183,7 +183,7 @@ function facility.new(num_reactors, cooling_conf)
 
                     unallocated = math.max(0, unallocated - ctl.br100)
 
-                    if last ~= ctl.br100 then u.a_commit_br100(ramp) end
+                    if last ~= ctl.br100 then u.auto_commit_br100(ramp) end
                 end
             end
         end
@@ -320,7 +320,7 @@ function facility.new(num_reactors, cooling_conf)
                             self.start_fail = START_STATUS.BLADE_MISMATCH
                         end
 
-                        if self.start_fail == START_STATUS.OK then u.a_engage() end
+                        if self.start_fail == START_STATUS.OK then u.auto_engage() end
 
                         self.max_burn_combined = self.max_burn_combined + (u.get_control_inf().lim_br100 / 100.0)
                     end
@@ -340,7 +340,7 @@ function facility.new(num_reactors, cooling_conf)
                     -- use manual SCRAM since inactive was requested, and automatic SCRAM trips an alarm
                     for _, u in pairs(self.prio_defs[i]) do
                         u.scram()
-                        u.a_disengage()
+                        u.auto_disengage()
                     end
                 end
 
@@ -601,7 +601,7 @@ function facility.new(num_reactors, cooling_conf)
                 -- SCRAM all units
                 for i = 1, #self.prio_defs do
                     for _, u in pairs(self.prio_defs[i]) do
-                        u.a_scram()
+                        u.auto_scram()
                     end
                 end
 
@@ -653,7 +653,7 @@ function facility.new(num_reactors, cooling_conf)
                 -- reset PLC RPS trips if we should
                 for i = 1, #self.units do
                     local u = self.units[i] ---@type reactor_unit
-                    u.a_cond_rps_reset()
+                    u.auto_cond_rps_reset()
                 end
             end
         end
diff --git a/supervisor/panel/components/pdg_entry.lua b/supervisor/panel/components/pdg_entry.lua
new file mode 100644
index 0000000..1e49fca
--- /dev/null
+++ b/supervisor/panel/components/pdg_entry.lua
@@ -0,0 +1,46 @@
+--
+-- Pocket Diagnostics Connection Entry
+--
+
+local databus       = require("supervisor.databus")
+
+local core          = require("graphics.core")
+
+local Div           = require("graphics.elements.div")
+local TextBox       = require("graphics.elements.textbox")
+
+local DataIndicator = require("graphics.elements.indicators.data")
+
+local TEXT_ALIGN = core.TEXT_ALIGN
+
+local cpair = core.cpair
+
+-- create a pocket diagnostics list entry
+---@param parent graphics_element parent
+---@param id integer PDG session ID
+local function init(parent, id)
+    -- root div
+    local root = Div{parent=parent,x=2,y=2,height=4,width=parent.get_width()-2,hidden=true}
+    local entry = Div{parent=root,x=2,y=1,height=3,fg_bg=cpair(colors.black,colors.white)}
+
+    local ps_prefix = "pdg_" .. id .. "_"
+
+    TextBox{parent=entry,x=1,y=1,text="",width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+    local pdg_addr = TextBox{parent=entry,x=1,y=2,text="@ C ??",alignment=TEXT_ALIGN.CENTER,width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray),nav_active=cpair(colors.gray,colors.black)}
+    TextBox{parent=entry,x=1,y=3,text="",width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+    pdg_addr.register(databus.ps, ps_prefix .. "addr", pdg_addr.set_value)
+
+    TextBox{parent=entry,x=10,y=2,text="FW:",width=3,height=1}
+    local pdg_fw_v = TextBox{parent=entry,x=14,y=2,text=" ------- ",width=20,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+    pdg_fw_v.register(databus.ps, ps_prefix .. "fw", pdg_fw_v.set_value)
+
+    TextBox{parent=entry,x=35,y=2,text="RTT:",width=4,height=1}
+    local pdg_rtt = DataIndicator{parent=entry,x=40,y=2,label="",unit="",format="%5d",value=0,width=5,fg_bg=cpair(colors.lightGray,colors.white)}
+    TextBox{parent=entry,x=46,y=2,text="ms",width=4,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+    pdg_rtt.register(databus.ps, ps_prefix .. "rtt", pdg_rtt.update)
+    pdg_rtt.register(databus.ps, ps_prefix .. "rtt_color", pdg_rtt.recolor)
+
+    return root
+end
+
+return init
diff --git a/supervisor/panel/components/rtu_entry.lua b/supervisor/panel/components/rtu_entry.lua
new file mode 100644
index 0000000..d9634e9
--- /dev/null
+++ b/supervisor/panel/components/rtu_entry.lua
@@ -0,0 +1,50 @@
+--
+-- RTU Connection Entry
+--
+
+local databus       = require("supervisor.databus")
+
+local core          = require("graphics.core")
+
+local Div           = require("graphics.elements.div")
+local TextBox       = require("graphics.elements.textbox")
+
+local DataIndicator = require("graphics.elements.indicators.data")
+
+local TEXT_ALIGN = core.TEXT_ALIGN
+
+local cpair = core.cpair
+
+-- create an RTU list entry
+---@param parent graphics_element parent
+---@param id integer RTU session ID
+local function init(parent, id)
+    -- root div
+    local root = Div{parent=parent,x=2,y=2,height=4,width=parent.get_width()-2,hidden=true}
+    local entry = Div{parent=root,x=2,y=1,height=3,fg_bg=cpair(colors.black,colors.white)}
+
+    local ps_prefix = "rtu_" .. id .. "_"
+
+    TextBox{parent=entry,x=1,y=1,text="",width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+    local rtu_addr = TextBox{parent=entry,x=1,y=2,text="@ C ??",alignment=TEXT_ALIGN.CENTER,width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray),nav_active=cpair(colors.gray,colors.black)}
+    TextBox{parent=entry,x=1,y=3,text="",width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+    rtu_addr.register(databus.ps, ps_prefix .. "addr", rtu_addr.set_value)
+
+    TextBox{parent=entry,x=10,y=2,text="UNITS:",width=7,height=1}
+    local unit_count = DataIndicator{parent=entry,x=17,y=2,label="",unit="",format="%2d",value=0,width=2,fg_bg=cpair(colors.gray,colors.white)}
+    unit_count.register(databus.ps, ps_prefix .. "units", unit_count.set_value)
+
+    TextBox{parent=entry,x=21,y=2,text="FW:",width=3,height=1}
+    local rtu_fw_v = TextBox{parent=entry,x=25,y=2,text=" ------- ",width=9,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+    rtu_fw_v.register(databus.ps, ps_prefix .. "fw", rtu_fw_v.set_value)
+
+    TextBox{parent=entry,x=36,y=2,text="RTT:",width=4,height=1}
+    local rtu_rtt = DataIndicator{parent=entry,x=40,y=2,label="",unit="",format="%5d",value=0,width=5,fg_bg=cpair(colors.lightGray,colors.white)}
+    TextBox{parent=entry,x=46,y=2,text="ms",width=4,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+    rtu_rtt.register(databus.ps, ps_prefix .. "rtt", rtu_rtt.update)
+    rtu_rtt.register(databus.ps, ps_prefix .. "rtt_color", rtu_rtt.recolor)
+
+    return root
+end
+
+return init
diff --git a/supervisor/panel/front_panel.lua b/supervisor/panel/front_panel.lua
new file mode 100644
index 0000000..b6ee692
--- /dev/null
+++ b/supervisor/panel/front_panel.lua
@@ -0,0 +1,164 @@
+--
+-- Main SCADA Coordinator GUI
+--
+
+local util          = require("scada-common.util")
+
+local config        = require("supervisor.config")
+local databus       = require("supervisor.databus")
+
+local pgi           = require("supervisor.panel.pgi")
+local style         = require("supervisor.panel.style")
+
+local pdg_entry     = require("supervisor.panel.components.pdg_entry")
+local rtu_entry     = require("supervisor.panel.components.rtu_entry")
+
+local core          = require("graphics.core")
+
+local Div           = require("graphics.elements.div")
+local ListBox       = require("graphics.elements.listbox")
+local MultiPane     = require("graphics.elements.multipane")
+local TextBox       = require("graphics.elements.textbox")
+
+local TabBar        = require("graphics.elements.controls.tabbar")
+
+local LED           = require("graphics.elements.indicators.led")
+local DataIndicator = require("graphics.elements.indicators.data")
+
+local TEXT_ALIGN = core.TEXT_ALIGN
+
+local cpair = core.cpair
+
+-- create new main view
+---@param panel graphics_element main displaybox
+local function init(panel)
+    TextBox{parent=panel,y=1,text="SCADA SUPERVISOR",alignment=TEXT_ALIGN.CENTER,height=1,fg_bg=style.header}
+
+    local page_div = Div{parent=panel,x=1,y=3}
+
+    --
+    -- system indicators
+    --
+
+    local main_page = Div{parent=page_div,x=1,y=1}
+
+    local system = Div{parent=main_page,width=14,height=17,x=2,y=2}
+
+    local on = LED{parent=system,label="STATUS",colors=cpair(colors.green,colors.red)}
+    local heartbeat = LED{parent=system,label="HEARTBEAT",colors=cpair(colors.green,colors.green_off)}
+    on.update(true)
+    system.line_break()
+
+    heartbeat.register(databus.ps, "heartbeat", heartbeat.update)
+
+    local modem = LED{parent=system,label="MODEM",colors=cpair(colors.green,colors.green_off)}
+    system.line_break()
+
+    modem.register(databus.ps, "has_modem", modem.update)
+
+---@diagnostic disable-next-line: undefined-field
+    local comp_id = util.sprintf("(%d)", os.getComputerID())
+    TextBox{parent=system,x=9,y=4,width=6,height=1,text=comp_id,fg_bg=cpair(colors.lightGray,colors.ivory)}
+
+    --
+    -- about footer
+    --
+
+    local about   = Div{parent=main_page,width=15,height=3,x=1,y=16,fg_bg=cpair(colors.lightGray,colors.ivory)}
+    local fw_v    = TextBox{parent=about,x=1,y=1,text="FW: v00.00.00",alignment=TEXT_ALIGN.LEFT,height=1}
+    local comms_v = TextBox{parent=about,x=1,y=2,text="NT: v00.00.00",alignment=TEXT_ALIGN.LEFT,height=1}
+
+    fw_v.register(databus.ps, "version", function (version) fw_v.set_value(util.c("FW: ", version)) end)
+    comms_v.register(databus.ps, "comms_version", function (version) comms_v.set_value(util.c("NT: v", version)) end)
+
+    --
+    -- page handling
+    --
+
+    -- plc page
+
+    local plc_page = Div{parent=page_div,x=1,y=1,hidden=true}
+    local plc_list = Div{parent=plc_page,x=2,y=2,width=49}
+
+    for i = 1, config.NUM_REACTORS do
+        local ps_prefix = "plc_" .. i .. "_"
+        local plc_entry = Div{parent=plc_list,height=3,fg_bg=cpair(colors.black,colors.white)}
+
+        TextBox{parent=plc_entry,x=1,y=1,text="",width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+        TextBox{parent=plc_entry,x=1,y=2,text="UNIT "..i,alignment=TEXT_ALIGN.CENTER,width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+        TextBox{parent=plc_entry,x=1,y=3,text="",width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray)}
+
+        local conn = LED{parent=plc_entry,x=10,y=2,label="LINK",colors=cpair(colors.green,colors.green_off)}
+        conn.register(databus.ps, ps_prefix .. "conn", conn.update)
+
+        local plc_addr = TextBox{parent=plc_entry,x=17,y=2,text=" --- ",width=5,height=1,fg_bg=cpair(colors.gray,colors.white)}
+        plc_addr.register(databus.ps, ps_prefix .. "addr", plc_addr.set_value)
+
+        TextBox{parent=plc_entry,x=23,y=2,text="FW:",width=3,height=1}
+        local plc_fw_v = TextBox{parent=plc_entry,x=27,y=2,text=" ------- ",width=9,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+        plc_fw_v.register(databus.ps, ps_prefix .. "fw", plc_fw_v.set_value)
+
+        TextBox{parent=plc_entry,x=37,y=2,text="RTT:",width=4,height=1}
+        local plc_rtt = DataIndicator{parent=plc_entry,x=42,y=2,label="",unit="",format="%4d",value=0,width=4,fg_bg=cpair(colors.lightGray,colors.white)}
+        TextBox{parent=plc_entry,x=47,y=2,text="ms",width=4,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+        plc_rtt.register(databus.ps, ps_prefix .. "rtt", plc_rtt.update)
+        plc_rtt.register(databus.ps, ps_prefix .. "rtt_color", plc_rtt.recolor)
+
+        plc_list.line_break()
+    end
+
+    -- rtu page
+
+    local rtu_page = Div{parent=page_div,x=1,y=1,hidden=true}
+    local rtu_list = ListBox{parent=rtu_page,x=1,y=1,height=17,width=51,scroll_height=1000,fg_bg=cpair(colors.black,colors.ivory),nav_fg_bg=cpair(colors.gray,colors.lightGray),nav_active=cpair(colors.black,colors.gray)}
+    local _ = Div{parent=rtu_list,height=1,hidden=true} -- padding
+
+    -- coordinator page
+
+    local crd_page = Div{parent=page_div,x=1,y=1,hidden=true}
+    local crd_box = Div{parent=crd_page,x=2,y=2,width=49,height=4,fg_bg=cpair(colors.black,colors.white)}
+
+    local crd_conn = LED{parent=crd_box,x=2,y=2,label="CONNECTION",colors=cpair(colors.green,colors.green_off)}
+    crd_conn.register(databus.ps, "crd_conn", crd_conn.update)
+
+    TextBox{parent=crd_box,x=4,y=3,text="COMPUTER",width=8,height=1,fg_bg=cpair(colors.gray,colors.white)}
+    local crd_addr = TextBox{parent=crd_box,x=13,y=3,text="---",width=5,height=1,fg_bg=cpair(colors.gray,colors.white)}
+    crd_addr.register(databus.ps, "crd_addr", crd_addr.set_value)
+
+    TextBox{parent=crd_box,x=22,y=2,text="FW:",width=3,height=1}
+    local crd_fw_v = TextBox{parent=crd_box,x=26,y=2,text=" ------- ",width=9,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+    crd_fw_v.register(databus.ps, "crd_fw", crd_fw_v.set_value)
+
+    TextBox{parent=crd_box,x=36,y=2,text="RTT:",width=4,height=1}
+    local crd_rtt = DataIndicator{parent=crd_box,x=41,y=2,label="",unit="",format="%5d",value=0,width=5,fg_bg=cpair(colors.lightGray,colors.white)}
+    TextBox{parent=crd_box,x=47,y=2,text="ms",width=4,height=1,fg_bg=cpair(colors.lightGray,colors.white)}
+    crd_rtt.register(databus.ps, "crd_rtt", crd_rtt.update)
+    crd_rtt.register(databus.ps, "crd_rtt_color", crd_rtt.recolor)
+
+    -- pocket diagnostics page
+
+    local pkt_page = Div{parent=page_div,x=1,y=1,hidden=true}
+    local pdg_list = ListBox{parent=pkt_page,x=1,y=1,height=17,width=51,scroll_height=1000,fg_bg=cpair(colors.black,colors.ivory),nav_fg_bg=cpair(colors.gray,colors.lightGray),nav_active=cpair(colors.black,colors.gray)}
+    local _ = Div{parent=pdg_list,height=1,hidden=true} -- padding
+
+    -- assemble page panes
+
+    local panes = { main_page, plc_page, rtu_page, crd_page, pkt_page }
+
+    local page_pane = MultiPane{parent=page_div,x=1,y=1,panes=panes}
+
+    local tabs = {
+        { name = "SVR", color = cpair(colors.black, colors.ivory) },
+        { name = "PLC", color = cpair(colors.black, colors.ivory) },
+        { name = "RTU", color = cpair(colors.black, colors.ivory) },
+        { name = "CRD", color = cpair(colors.black, colors.ivory) },
+        { name = "PKT", color = cpair(colors.black, colors.ivory) },
+    }
+
+    TabBar{parent=panel,y=2,tabs=tabs,min_width=9,callback=page_pane.set_value,fg_bg=cpair(colors.black,colors.white)}
+
+    -- link RTU/PDG list management to PGI
+    pgi.link_elements(rtu_list, rtu_entry, pdg_list, pdg_entry)
+end
+
+return init
diff --git a/supervisor/panel/pgi.lua b/supervisor/panel/pgi.lua
new file mode 100644
index 0000000..9065f72
--- /dev/null
+++ b/supervisor/panel/pgi.lua
@@ -0,0 +1,93 @@
+--
+-- Protected Graphics Interface
+--
+
+local log  = require("scada-common.log")
+local util = require("scada-common.util")
+
+local pgi = {}
+
+local data = {
+    rtu_list = nil,     ---@type nil|graphics_element
+    pdg_list = nil,     ---@type nil|graphics_element
+    rtu_entry = nil,    ---@type function
+    pdg_entry = nil,    ---@type function
+    -- session entries
+    s_entries = { rtu = {}, pdg = {} }
+}
+
+-- link list boxes
+---@param rtu_list graphics_element RTU list element
+---@param rtu_entry function RTU entry constructor
+---@param pdg_list graphics_element pocket diagnostics list element
+---@param pdg_entry function pocket diagnostics entry constructor
+function pgi.link_elements(rtu_list, rtu_entry, pdg_list, pdg_entry)
+    data.rtu_list = rtu_list
+    data.pdg_list = pdg_list
+    data.rtu_entry = rtu_entry
+    data.pdg_entry = pdg_entry
+end
+
+-- unlink all fields, disabling the PGI
+function pgi.unlink()
+    data.rtu_list = nil
+    data.pdg_list = nil
+    data.rtu_entry = nil
+    data.pdg_entry = nil
+end
+
+-- add an RTU entry to the RTU list
+---@param session_id integer RTU session
+function pgi.create_rtu_entry(session_id)
+    if data.rtu_list ~= nil and data.rtu_entry ~= nil then
+        local success, result = pcall(data.rtu_entry, data.rtu_list, session_id)
+
+        if success then
+            data.s_entries.rtu[session_id] = result
+        else
+            log.error(util.c("PGI: failed to create RTU entry (", result, ")"), true)
+        end
+    end
+end
+
+-- delete an RTU entry from the RTU list
+---@param session_id integer RTU session
+function pgi.delete_rtu_entry(session_id)
+    if data.s_entries.rtu[session_id] ~= nil then
+        local success, result = pcall(data.s_entries.rtu[session_id].delete)
+        data.s_entries.rtu[session_id] = nil
+
+        if not success then
+            log.error(util.c("PGI: failed to delete RTU entry (", result, ")"), true)
+        end
+    end
+end
+
+-- add a PDG entry to the PDG list
+---@param session_id integer pocket diagnostics session
+function pgi.create_pdg_entry(session_id)
+    if data.pdg_list ~= nil and data.pdg_entry ~= nil then
+        local success, result = pcall(data.pdg_entry, data.pdg_list, session_id)
+
+        if success then
+            data.s_entries.pdg[session_id] = result
+        else
+            log.error(util.c("PGI: failed to create PDG entry (", result, ")"), true)
+        end
+    end
+end
+
+-- delete a PDG entry from the PDG list
+---@param session_id integer pocket diagnostics session
+function pgi.delete_pdg_entry(session_id)
+    if data.s_entries.pdg[session_id] ~= nil then
+        local success, result = pcall(data.s_entries.pdg[session_id].delete)
+        data.s_entries.pdg[session_id] = nil
+
+        if not success then
+            log.error(util.c("PGI: failed to delete PDG entry (", result, ")"), true)
+        end
+    end
+end
+
+return pgi
diff --git a/supervisor/panel/style.lua b/supervisor/panel/style.lua
new file mode 100644
index 0000000..0668ccc
--- /dev/null
+++ b/supervisor/panel/style.lua
@@ -0,0 +1,42 @@
+--
+-- Graphics Style Options
+--
+
+local core = require("graphics.core")
+
+local style = {}
+
+local cpair = core.cpair
+
+-- GLOBAL --
+
+-- remap global colors
+colors.ivory = colors.pink
+colors.yellow_hc = colors.purple
+colors.red_off = colors.brown
+colors.yellow_off = colors.magenta
+colors.green_off = colors.lime
+
+style.root = cpair(colors.black, colors.ivory)
+style.header = cpair(colors.black, colors.lightGray)
+
+style.colors = {
+    { c = colors.red,       hex = 0xdf4949 },   -- RED ON
+    { c = colors.orange,    hex = 0xffb659 },
+    { c = colors.yellow,    hex = 0xf9fb53 },   -- YELLOW ON
+    { c = colors.lime,      hex = 0x16665a },   -- GREEN OFF
+    { c = colors.green,     hex = 0x6be551 },   -- GREEN ON
+    { c = colors.cyan,      hex = 0x34bac8 },
+    { c = colors.lightBlue, hex = 0x6cc0f2 },
+    { c = colors.blue,      hex = 0x0008fe },   -- LCD BLUE
+    { c = colors.purple,    hex = 0xe3bc2a },   -- YELLOW HIGH CONTRAST
+    { c = colors.pink,      hex = 0xdcd9ca },   -- IVORY
+    { c = colors.magenta,   hex = 0x85862c },   -- YELLOW OFF
+    -- { c = colors.white,     hex = 0xdcd9ca },
+    { c = colors.lightGray, hex = 0xb1b8b3 },
+    { c = colors.gray,      hex = 0x575757 },
+    -- { c = colors.black,     hex = 0x191919 },
+    { c = colors.brown,     hex = 0x672223 }    -- RED OFF
+}
+
+return style
diff --git a/supervisor/renderer.lua b/supervisor/renderer.lua
new file mode 100644
index 0000000..1bc70a4
--- /dev/null
+++ b/supervisor/renderer.lua
@@ -0,0 +1,84 @@
+--
+-- Graphics Rendering Control
+--
+
+local panel_view = require("supervisor.panel.front_panel")
+local pgi        = require("supervisor.panel.pgi")
+local style      = require("supervisor.panel.style")
+
+local flasher    = require("graphics.flasher")
+
+local DisplayBox = require("graphics.elements.displaybox")
+
+local renderer = {}
+
+local ui = {
+    display = nil
+}
+
+-- start the UI
+function renderer.start_ui()
+    if ui.display == nil then
+        -- reset terminal
+        term.setTextColor(colors.white)
+        term.setBackgroundColor(colors.black)
+        term.clear()
+        term.setCursorPos(1, 1)
+
+        -- set overridden colors
+        for i = 1, #style.colors do
+            term.setPaletteColor(style.colors[i].c, style.colors[i].hex)
+        end
+
+        -- init front panel view
+        ui.display = DisplayBox{window=term.current(),fg_bg=style.root}
+        panel_view(ui.display)
+
+        -- start flasher callback task
+        flasher.run()
+    end
+end
+
+-- close out the UI
+function renderer.close_ui()
+    if ui.display ~= nil then
+        -- stop blinking indicators
+        flasher.clear()
+
+        -- disable PGI
+        pgi.unlink()
+
+        -- hide to stop animation callbacks
+        ui.display.hide()
+
+        -- clear root UI elements
+        ui.display = nil
+
+        -- restore colors
+        for i = 1, #style.colors do
+            local r, g, b = term.nativePaletteColor(style.colors[i].c)
+            term.setPaletteColor(style.colors[i].c, r, g, b)
+        end
+
+        -- reset terminal
+        term.setTextColor(colors.white)
+        term.setBackgroundColor(colors.black)
+        term.clear()
+        term.setCursorPos(1, 1)
+    end
+end
+
+-- is the UI ready?
+---@nodiscard
+---@return boolean ready
+function renderer.ui_ready() return ui.display ~= nil end
+
+-- handle a mouse event
+---@param event mouse_interaction|nil
+function renderer.handle_mouse(event)
+    if ui.display ~= nil and event ~= nil then
+        ui.display.handle_mouse(event)
+    end
+end
+
+return renderer
diff --git a/supervisor/session/coordinator.lua b/supervisor/session/coordinator.lua
index b093d87..1b75078 100644
--- a/supervisor/session/coordinator.lua
+++ b/supervisor/session/coordinator.lua
@@ -4,6 +4,8 @@ local mqueue   = require("scada-common.mqueue")
 local types    = require("scada-common.types")
 local util     = require("scada-common.util")
 
+local databus  = require("supervisor.databus")
+
 local svqtypes = require("supervisor.session.svqtypes")
 
 local coordinator = {}
@@ -18,8 +20,6 @@ local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 
 local SV_Q_DATA = svqtypes.SV_Q_DATA
 
-local println = util.println
-
 -- retry time constants in ms
 -- local INITIAL_WAIT = 1500
 local RETRY_PERIOD = 1000
@@ -45,11 +45,16 @@ local PERIODICS = {
 -- coordinator supervisor session
 ---@nodiscard
 ---@param id integer session ID
+---@param s_addr integer device source address
 ---@param in_queue mqueue in message queue
 ---@param out_queue mqueue out message queue
 ---@param timeout number communications timeout
 ---@param facility facility facility data table
-function coordinator.new_session(id, in_queue, out_queue, timeout, facility)
+---@param fp_ok boolean if the front panel UI is running
+function coordinator.new_session(id, s_addr, in_queue, out_queue, timeout, facility, fp_ok)
+    -- print a log message to the terminal as long as the UI isn't running
+    local function println(message) if not fp_ok then util.println_ts(message) end end
+
     local log_header = "crdn_session(" .. id .. "): "
 
     local self = {
@@ -84,6 +89,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility)
     local function _close()
         self.conn_watchdog.cancel()
         self.connected = false
+        databus.tx_crd_disconnected()
     end
 
     -- send a CRDN packet
@@ -94,7 +100,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility)
         local c_pkt = comms.crdn_packet()
 
         c_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_CRDN, c_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.SCADA_CRDN, c_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -108,7 +114,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility)
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -205,6 +211,8 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility)
 
                     -- log.debug(log_header .. "COORD RTT = " .. self.last_rtt .. "ms")
                     -- log.debug(log_header .. "COORD TT  = " .. (srv_now - coord_send) .. "ms")
+
+                    databus.tx_crd_rtt(self.last_rtt)
                 else
                     log.debug(log_header .. "SCADA keep alive packet length mismatch")
                 end
@@ -327,7 +335,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility)
         end
     end
 
-    ---@class coord_session
+    ---@class crd_session
     local public = {}
 
     -- get the session ID
diff --git a/supervisor/session/plc.lua b/supervisor/session/plc.lua
index cca8a26..ac80ea6 100644
--- a/supervisor/session/plc.lua
+++ b/supervisor/session/plc.lua
@@ -4,6 +4,8 @@ local mqueue   = require("scada-common.mqueue")
 local types    = require("scada-common.types")
 local util     = require("scada-common.util")
 
+local databus  = require("supervisor.databus")
+
 local svqtypes = require("supervisor.session.svqtypes")
 
 local plc = {}
@@ -14,8 +16,6 @@ local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
 local PLC_AUTO_ACK = comms.PLC_AUTO_ACK
 local UNIT_COMMAND = comms.UNIT_COMMAND
 
-local println = util.println
-
 -- retry time constants in ms
 local INITIAL_WAIT      = 1500
 local INITIAL_AUTO_WAIT = 1000
@@ -45,11 +45,16 @@ local PERIODICS = {
 -- PLC supervisor session
 ---@nodiscard
 ---@param id integer session ID
+---@param s_addr integer device source address
 ---@param reactor_id integer reactor ID
 ---@param in_queue mqueue in message queue
 ---@param out_queue mqueue out message queue
 ---@param timeout number communications timeout
-function plc.new_session(id, reactor_id, in_queue, out_queue, timeout)
+---@param fp_ok boolean if the front panel UI is running
+function plc.new_session(id, s_addr, reactor_id, in_queue, out_queue, timeout, fp_ok)
+    -- print a log message to the terminal as long as the UI isn't running
+    local function println(message) if not fp_ok then util.println_ts(message) end end
+
     local log_header = "plc_session(" .. id .. "): "
 
     local self = {
@@ -235,6 +240,7 @@ function plc.new_session(id, reactor_id, in_queue, out_queue, timeout)
     local function _close()
         self.conn_watchdog.cancel()
         self.connected = false
+        databus.tx_plc_disconnected(reactor_id)
     end
 
     -- send an RPLC packet
@@ -245,7 +251,7 @@ function plc.new_session(id, reactor_id, in_queue, out_queue, timeout)
         local r_pkt = comms.rplc_packet()
 
         r_pkt.make(reactor_id, msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.RPLC, r_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.RPLC, r_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -259,7 +265,7 @@ function plc.new_session(id, reactor_id, in_queue, out_queue, timeout)
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -485,6 +491,8 @@ function plc.new_session(id, reactor_id, in_queue, out_queue, timeout)
 
                     -- log.debug(log_header .. "PLC RTT = " .. self.last_rtt .. "ms")
                     -- log.debug(log_header .. "PLC TT  = " .. (srv_now - plc_send) .. "ms")
+
+                    databus.tx_plc_rtt(reactor_id, self.last_rtt)
                 else
                     log.debug(log_header .. "SCADA keep alive packet length mismatch")
                 end
diff --git a/supervisor/session/pocket.lua b/supervisor/session/pocket.lua
index 9cf0a5d..9de55ab 100644
--- a/supervisor/session/pocket.lua
+++ b/supervisor/session/pocket.lua
@@ -1,15 +1,14 @@
-local comms    = require("scada-common.comms")
-local log      = require("scada-common.log")
-local mqueue   = require("scada-common.mqueue")
-local util     = require("scada-common.util")
+local comms   = require("scada-common.comms")
+local log     = require("scada-common.log")
+local mqueue  = require("scada-common.mqueue")
+local util    = require("scada-common.util")
+local databus = require("supervisor.databus")
 
 local pocket = {}
 
 local PROTOCOL = comms.PROTOCOL
 local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
 
-local println = util.println
-
 -- retry time constants in ms
 -- local INITIAL_WAIT = 1500
 -- local RETRY_PERIOD = 1000
@@ -30,11 +29,16 @@ local PERIODICS = {
 -- pocket diagnostics session
 ---@nodiscard
 ---@param id integer session ID
+---@param s_addr integer device source address
 ---@param in_queue mqueue in message queue
 ---@param out_queue mqueue out message queue
 ---@param timeout number communications timeout
-function pocket.new_session(id, in_queue, out_queue, timeout)
-    local log_header = "diag_session(" .. id .. "): "
+---@param fp_ok boolean if the front panel UI is running
+function pocket.new_session(id, s_addr, in_queue, out_queue, timeout, fp_ok)
+    -- print a log message to the terminal as long as the UI isn't running
+    local function println(message) if not fp_ok then util.println_ts(message) end end
+
+    local log_header = "pdg_session(" .. id .. "): "
 
     local self = {
         -- connection properties
@@ -55,18 +59,19 @@ function pocket.new_session(id, in_queue, out_queue, timeout)
         acks = {
         },
         -- session database
-        ---@class diag_db
+        ---@class pdg_db
         sDB = {
         }
     }
 
-    ---@class diag_session
+    ---@class pdg_session
     local public = {}
 
     -- mark this diagnostics session as closed, stop watchdog
     local function _close()
         self.conn_watchdog.cancel()
         self.connected = false
+        databus.tx_pdg_disconnected(id)
     end
 
     -- send a SCADA management packet
@@ -77,7 +82,7 @@ function pocket.new_session(id, in_queue, out_queue, timeout)
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -106,16 +111,18 @@ function pocket.new_session(id, in_queue, out_queue, timeout)
                 -- keep alive reply
                 if pkt.length == 2 then
                     local srv_start = pkt.data[1]
-                    -- local diag_send = pkt.data[2]
+                    -- local pdg_send = pkt.data[2]
                     local srv_now = util.time()
                     self.last_rtt = srv_now - srv_start
 
                     if self.last_rtt > 750 then
-                        log.warning(log_header .. "DIAG KEEP_ALIVE round trip time > 750ms (" .. self.last_rtt .. "ms)")
+                        log.warning(log_header .. "PDG KEEP_ALIVE round trip time > 750ms (" .. self.last_rtt .. "ms)")
                     end
 
-                    -- log.debug(log_header .. "DIAG RTT = " .. self.last_rtt .. "ms")
-                    -- log.debug(log_header .. "DIAG TT  = " .. (srv_now - diag_send) .. "ms")
+                    -- log.debug(log_header .. "PDG RTT = " .. self.last_rtt .. "ms")
+                    -- log.debug(log_header .. "PDG TT  = " .. (srv_now - pdg_send) .. "ms")
+
+                    databus.tx_pdg_rtt(id, self.last_rtt)
                 else
                     log.debug(log_header .. "SCADA keep alive packet length mismatch")
                 end
diff --git a/supervisor/session/rtu.lua b/supervisor/session/rtu.lua
index b494aa6..d1fbaec 100644
--- a/supervisor/session/rtu.lua
+++ b/supervisor/session/rtu.lua
@@ -4,6 +4,8 @@ local mqueue        = require("scada-common.mqueue")
 local types         = require("scada-common.types")
 local util          = require("scada-common.util")
 
+local databus       = require("supervisor.databus")
+
 local svqtypes      = require("supervisor.session.svqtypes")
 
 -- supervisor rtu sessions (svrs)
@@ -22,8 +24,6 @@ local PROTOCOL = comms.PROTOCOL
 local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
 local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 
-local println = util.println
-
 local PERIODICS = {
     KEEP_ALIVE = 2000
 }
@@ -31,12 +31,17 @@ local PERIODICS = {
 -- create a new RTU session
 ---@nodiscard
 ---@param id integer session ID
+---@param s_addr integer device source address
 ---@param in_queue mqueue in message queue
 ---@param out_queue mqueue out message queue
 ---@param timeout number communications timeout
 ---@param advertisement table RTU device advertisement
 ---@param facility facility facility data table
-function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facility)
+---@param fp_ok boolean if the front panel UI is running
+function rtu.new_session(id, s_addr, in_queue, out_queue, timeout, advertisement, facility, fp_ok)
+    -- print a log message to the terminal as long as the UI isn't running
+    local function println(message) if not fp_ok then util.println_ts(message) end end
+
     local log_header = "rtu_session(" .. id .. "): "
 
     local self = {
@@ -66,6 +71,8 @@ function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facili
 
     -- parse the recorded advertisement and create unit sub-sessions
     local function _handle_advertisement()
+        local unit_count = 0
+
         _reset_config()
 
         for i = 1, #self.fac_units do
@@ -172,18 +179,22 @@ function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facili
 
             if unit ~= nil then
                 self.units[i] = unit
+                unit_count = unit_count + 1
             elseif u_type ~= RTU_UNIT_TYPE.VIRTUAL then
                 _reset_config()
                 log.error(util.c(log_header, "bad advertisement: error occured while creating a unit (type is ", type_string, ")"))
                 break
             end
         end
+
+        databus.tx_rtu_units(id, unit_count)
     end
 
     -- mark this RTU session as closed, stop watchdog
     local function _close()
         self.conn_watchdog.cancel()
         self.connected = false
+        databus.tx_rtu_disconnected(id)
 
         -- mark all RTU unit sessions as closed so the reactor unit knows
         for _, unit in pairs(self.units) do unit.close() end
@@ -194,7 +205,7 @@ function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facili
     local function _send_modbus(m_pkt)
         local s_pkt = comms.scada_packet()
 
-        s_pkt.make(self.seq_num, PROTOCOL.MODBUS_TCP, m_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.MODBUS_TCP, m_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -208,7 +219,7 @@ function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facili
         local m_pkt = comms.mgmt_packet()
 
         m_pkt.make(msg_type, msg)
-        s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        s_pkt.make(s_addr, self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
         out_queue.push_packet(s_pkt)
         self.seq_num = self.seq_num + 1
@@ -254,6 +265,8 @@ function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facili
 
                     -- log.debug(log_header .. "RTU RTT = " .. self.last_rtt .. "ms")
                     -- log.debug(log_header .. "RTU TT  = " .. (srv_now - rtu_send) .. "ms")
+
+                    databus.tx_rtu_rtt(id, self.last_rtt)
                 else
                     log.debug(log_header .. "SCADA keep alive packet length mismatch")
                 end
diff --git a/supervisor/session/svsessions.lua b/supervisor/session/svsessions.lua
index 8ad3366..a311ab9 100644
--- a/supervisor/session/svsessions.lua
+++ b/supervisor/session/svsessions.lua
@@ -3,6 +3,7 @@ local mqueue      = require("scada-common.mqueue")
 local util        = require("scada-common.util")
 
 local config      = require("supervisor.config")
+local databus     = require("supervisor.databus")
 local facility    = require("supervisor.facility")
 
 local svqtypes    = require("supervisor.session.svqtypes")
@@ -22,24 +23,26 @@ local CRD_S_DATA = coordinator.CRD_S_DATA
 
 local svsessions = {}
 
+---@enum SESSION_TYPE
 local SESSION_TYPE = {
     RTU_SESSION = 0,    -- RTU gateway
     PLC_SESSION = 1,    -- reactor PLC
-    COORD_SESSION = 2,  -- coordinator
-    DIAG_SESSION = 3    -- pocket diagnostics
+    CRD_SESSION = 2,    -- coordinator
+    PDG_SESSION = 3     -- pocket diagnostics
 }
 
 svsessions.SESSION_TYPE = SESSION_TYPE
 
 local self = {
     modem = nil,        ---@type table|nil
+    fp_ok = false,
     num_reactors = 0,
     facility = nil,     ---@type facility|nil
-    sessions = { rtu = {}, plc = {}, coord = {}, diag = {} },
-    next_ids = { rtu = 0, plc = 0, coord = 0, diag = 0 }
+    sessions = { rtu = {}, plc = {}, crd = {}, pdg = {} },
+    next_ids = { rtu = 0, plc = 0, crd = 0, pdg = 0 }
 }
 
----@alias sv_session_structs plc_session_struct|rtu_session_struct|coord_session_struct|diag_session_struct
+---@alias sv_session_structs plc_session_struct|rtu_session_struct|crd_session_struct|pdg_session_struct
 
 -- PRIVATE FUNCTIONS --
 
@@ -57,7 +60,7 @@ local function _sv_handle_outq(session)
         if msg ~= nil then
             if msg.qtype == mqueue.TYPE.PACKET then
                 -- handle a packet to be sent
-                self.modem.transmit(session.r_port, session.l_port, msg.message.raw_sendable())
+                self.modem.transmit(session.r_chan, config.SVR_CHANNEL, msg.message.raw_sendable())
             elseif msg.qtype == mqueue.TYPE.COMMAND then
                 -- handle instruction/notification
             elseif msg.qtype == mqueue.TYPE.DATA then
@@ -78,11 +81,11 @@ local function _sv_handle_outq(session)
                         elseif cmd.key == SV_Q_DATA.SET_BURN and type(cmd.val) == "table" and #cmd.val == 2 then
                             plc_s.in_queue.push_data(PLC_S_DATA.BURN_RATE, cmd.val[2])
                         else
-                            log.debug(util.c("unknown PLC SV queue command ", cmd.key))
+                            log.debug(util.c("[SVS] unknown PLC SV queue command ", cmd.key))
                         end
                     end
                 else
-                    local crd_s = svsessions.get_coord_session()
+                    local crd_s = svsessions.get_crd_session()
                     if crd_s ~= nil then
                         if cmd.key == SV_Q_DATA.CRDN_ACK then
                             -- ack to be sent to coordinator
@@ -101,8 +104,8 @@ local function _sv_handle_outq(session)
 
         -- max 100ms spent processing queue
         if util.time() - handle_start > 100 then
-            log.warning("supervisor out queue handler exceeded 100ms queue process limit")
-            log.warning(util.c("offending session: port ", session.r_port, " type '", session.s_type, "'"))
+            log.warning("[SVS] supervisor out queue handler exceeded 100ms queue process limit")
+            log.warning(util.c("[SVS] offending session: ", session))
             break
         end
     end
@@ -128,15 +131,15 @@ local function _shutdown(session)
     session.open = false
     session.instance.close()
 
-    -- send packets in out queue (namely the close packet)
+    -- send packets in out queue (for the close packet)
     while session.out_queue.ready() do
         local msg = session.out_queue.pop()
         if msg ~= nil and msg.qtype == mqueue.TYPE.PACKET then
-            self.modem.transmit(session.r_port, session.l_port, msg.message.raw_sendable())
+            self.modem.transmit(session.r_chan, config.SVR_CHANNEL, msg.message.raw_sendable())
         end
     end
 
-    log.debug(util.c("closed ", session.s_type, " session ", session.instance.get_id(), " on remote port ", session.r_port))
+    log.debug(util.c("[SVS] closed session ", session))
 end
 
 -- close connections
@@ -157,8 +160,7 @@ local function _check_watchdogs(sessions, timer_event)
         if session.open then
             local triggered = session.instance.check_wd(timer_event)
             if triggered then
-                log.debug(util.c("watchdog closing ", session.s_type, " session ", session.instance.get_id(),
-                    " on remote port ", session.r_port, "..."))
+                log.debug(util.c("[SVS] watchdog closing session ", session, "..."))
                 _shutdown(session)
             end
         end
@@ -172,21 +174,20 @@ local function _free_closed(sessions)
 
     ---@param session sv_session_structs
     local on_delete = function (session)
-        log.debug(util.c("free'ing closed ", session.s_type, " session ", session.instance.get_id(),
-            " on remote port ", session.r_port))
+        log.debug(util.c("[SVS] free'ing closed session ", session))
     end
 
     util.filter_table(sessions, f, on_delete)
 end
 
--- find a session by remote port
+-- find a session by computer ID
 ---@nodiscard
 ---@param list table
----@param port integer
+---@param s_addr integer
 ---@return sv_session_structs|nil
-local function _find_session(list, port)
+local function _find_session(list, s_addr)
     for i = 1, #list do
-        if list[i].r_port == port then return list[i] end
+        if list[i].s_addr == s_addr then return list[i] end
     end
     return nil
 end
@@ -194,11 +195,13 @@ end
 -- PUBLIC FUNCTIONS --
 
 -- initialize svsessions
----@param modem table
----@param num_reactors integer
----@param cooling_conf table
-function svsessions.init(modem, num_reactors, cooling_conf)
+---@param modem table modem device
+---@param fp_ok boolean front panel active
+---@param num_reactors integer number of reactors
+---@param cooling_conf table cooling configuration definition
+function svsessions.init(modem, fp_ok, num_reactors, cooling_conf)
     self.modem = modem
+    self.fp_ok = fp_ok
     self.num_reactors = num_reactors
     self.facility = facility.new(num_reactors, cooling_conf)
 end
@@ -209,63 +212,55 @@ function svsessions.relink_modem(modem)
     self.modem = modem
 end
 
--- find an RTU session by the remote port
+-- find an RTU session by the computer ID
 ---@nodiscard
----@param remote_port integer
+---@param source_addr integer
 ---@return rtu_session_struct|nil
-function svsessions.find_rtu_session(remote_port)
+function svsessions.find_rtu_session(source_addr)
     -- check RTU sessions
-    local session = _find_session(self.sessions.rtu, remote_port)
+    local session = _find_session(self.sessions.rtu, source_addr)
     ---@cast session rtu_session_struct|nil
     return session
 end
 
--- find a PLC session by the remote port
+-- find a PLC session by the computer ID
 ---@nodiscard
----@param remote_port integer
+---@param source_addr integer
 ---@return plc_session_struct|nil
-function svsessions.find_plc_session(remote_port)
+function svsessions.find_plc_session(source_addr)
     -- check PLC sessions
-    local session = _find_session(self.sessions.plc, remote_port)
+    local session = _find_session(self.sessions.plc, source_addr)
     ---@cast session plc_session_struct|nil
     return session
 end
 
--- find a PLC/RTU session by the remote port
+-- find a coordinator session by the computer ID
 ---@nodiscard
----@param remote_port integer
----@return plc_session_struct|rtu_session_struct|nil
-function svsessions.find_device_session(remote_port)
-    -- check RTU sessions
-    local session = _find_session(self.sessions.rtu, remote_port)
-
-    -- check PLC sessions
-    if session == nil then session = _find_session(self.sessions.plc, remote_port) end
-    ---@cast session plc_session_struct|rtu_session_struct|nil
-
+---@param source_addr integer
+---@return crd_session_struct|nil
+function svsessions.find_crd_session(source_addr)
+    -- check coordinator sessions
+    local session = _find_session(self.sessions.crd, source_addr)
+    ---@cast session crd_session_struct|nil
     return session
 end
 
--- find a coordinator or diagnostic access session by the remote port
+-- find a pocket diagnostics session by the computer ID
 ---@nodiscard
----@param remote_port integer
----@return coord_session_struct|diag_session_struct|nil
-function svsessions.find_svctl_session(remote_port)
-    -- check coordinator sessions
-    local session = _find_session(self.sessions.coord, remote_port)
-
+---@param source_addr integer
+---@return pdg_session_struct|nil
+function svsessions.find_pdg_session(source_addr)
     -- check diagnostic sessions
-    if session == nil then session = _find_session(self.sessions.diag, remote_port) end
-    ---@cast session coord_session_struct|diag_session_struct|nil
-
+    local session = _find_session(self.sessions.pdg, source_addr)
+    ---@cast session pdg_session_struct|nil
     return session
 end
 
 -- get the a coordinator session if exists
 ---@nodiscard
----@return coord_session_struct|nil
-function svsessions.get_coord_session()
-    return self.sessions.coord[1]
+---@return crd_session_struct|nil
+function svsessions.get_crd_session()
+    return self.sessions.crd[1]
 end
 
 -- get a session by reactor ID
@@ -286,12 +281,11 @@ end
 
 -- establish a new PLC session
 ---@nodiscard
----@param local_port integer
----@param remote_port integer
+---@param source_addr integer
 ---@param for_reactor integer
 ---@param version string
 ---@return integer|false session_id
-function svsessions.establish_plc_session(local_port, remote_port, for_reactor, version)
+function svsessions.establish_plc_session(source_addr, for_reactor, version)
     if svsessions.get_reactor_session(for_reactor) == nil and for_reactor >= 1 and for_reactor <= self.num_reactors then
         ---@class plc_session_struct
         local plc_s = {
@@ -299,22 +293,34 @@ function svsessions.establish_plc_session(local_port, remote_port, for_reactor,
             open = true,
             reactor = for_reactor,
             version = version,
-            l_port = local_port,
-            r_port = remote_port,
+            r_chan = config.PLC_CHANNEL,
+            s_addr = source_addr,
             in_queue = mqueue.new(),
             out_queue = mqueue.new(),
             instance = nil  ---@type plc_session
         }
 
-        plc_s.instance = plc.new_session(self.next_ids.plc, for_reactor, plc_s.in_queue, plc_s.out_queue, config.PLC_TIMEOUT)
+        local id = self.next_ids.plc
+
+        plc_s.instance = plc.new_session(id, source_addr, for_reactor, plc_s.in_queue, plc_s.out_queue,
+                                            config.PLC_TIMEOUT, self.fp_ok)
         table.insert(self.sessions.plc, plc_s)
 
         local units = self.facility.get_units()
         units[for_reactor].link_plc_session(plc_s)
 
-        log.debug(util.c("established new PLC session to ", remote_port, " with ID ", self.next_ids.plc, " for reactor ", for_reactor))
+        local mt = {
+            ---@param s plc_session_struct
+            __tostring = function (s)  return util.c("PLC [", s.instance.get_id(), "] for reactor #", s.reactor,
+                                                        " (@", s.s_addr, ")") end
+        }
 
-        self.next_ids.plc = self.next_ids.plc + 1
+        setmetatable(plc_s, mt)
+
+        databus.tx_plc_connected(for_reactor, version, source_addr)
+        log.debug(util.c("[SVS] established new session: ", plc_s))
+
+        self.next_ids.plc = id + 1
 
         -- success
         return plc_s.instance.get_id()
@@ -326,64 +332,84 @@ end
 
 -- establish a new RTU session
 ---@nodiscard
----@param local_port integer
----@param remote_port integer
+---@param source_addr integer
 ---@param advertisement table
 ---@param version string
 ---@return integer session_id
-function svsessions.establish_rtu_session(local_port, remote_port, advertisement, version)
+function svsessions.establish_rtu_session(source_addr, advertisement, version)
     ---@class rtu_session_struct
     local rtu_s = {
         s_type = "rtu",
         open = true,
         version = version,
-        l_port = local_port,
-        r_port = remote_port,
+        r_chan = config.RTU_CHANNEL,
+        s_addr = source_addr,
         in_queue = mqueue.new(),
         out_queue = mqueue.new(),
         instance = nil  ---@type rtu_session
     }
 
-    rtu_s.instance = rtu.new_session(self.next_ids.rtu, rtu_s.in_queue, rtu_s.out_queue, config.RTU_TIMEOUT, advertisement, self.facility)
+    local id = self.next_ids.rtu
+
+    rtu_s.instance = rtu.new_session(id, source_addr, rtu_s.in_queue, rtu_s.out_queue, config.RTU_TIMEOUT,
+                                        advertisement, self.facility, self.fp_ok)
     table.insert(self.sessions.rtu, rtu_s)
 
-    log.debug("established new RTU session to " .. remote_port .. " with ID " .. self.next_ids.rtu)
+    local mt = {
+        ---@param s rtu_session_struct
+        __tostring = function (s)  return util.c("RTU [", s.instance.get_id(), "] (@", s.s_addr, ")") end
+    }
 
-    self.next_ids.rtu = self.next_ids.rtu + 1
+    setmetatable(rtu_s, mt)
+
+    databus.tx_rtu_connected(id, version, source_addr)
+    log.debug(util.c("[SVS] established new session: ", rtu_s))
+
+    self.next_ids.rtu = id + 1
 
     -- success
-    return rtu_s.instance.get_id()
+    return id
 end
 
 -- establish a new coordinator session
 ---@nodiscard
----@param local_port integer
----@param remote_port integer
+---@param source_addr integer
 ---@param version string
 ---@return integer|false session_id
-function svsessions.establish_coord_session(local_port, remote_port, version)
-    if svsessions.get_coord_session() == nil then
-        ---@class coord_session_struct
-        local coord_s = {
+function svsessions.establish_crd_session(source_addr, version)
+    if svsessions.get_crd_session() == nil then
+        ---@class crd_session_struct
+        local crd_s = {
             s_type = "crd",
             open = true,
             version = version,
-            l_port = local_port,
-            r_port = remote_port,
+            r_chan = config.CRD_CHANNEL,
+            s_addr = source_addr,
             in_queue = mqueue.new(),
             out_queue = mqueue.new(),
-            instance = nil  ---@type coord_session
+            instance = nil  ---@type crd_session
         }
 
-        coord_s.instance = coordinator.new_session(self.next_ids.coord, coord_s.in_queue, coord_s.out_queue, config.CRD_TIMEOUT, self.facility)
-        table.insert(self.sessions.coord, coord_s)
+        local id = self.next_ids.crd
 
-        log.debug("established new coordinator session to " .. remote_port .. " with ID " .. self.next_ids.coord)
+        crd_s.instance = coordinator.new_session(id, source_addr, crd_s.in_queue, crd_s.out_queue, config.CRD_TIMEOUT,
+                                                    self.facility, self.fp_ok)
+        table.insert(self.sessions.crd, crd_s)
 
-        self.next_ids.coord = self.next_ids.coord + 1
+        local mt = {
+            ---@param s crd_session_struct
+            __tostring = function (s)  return util.c("CRD [", s.instance.get_id(), "] (@", s.s_addr, ")") end
+        }
+
+        setmetatable(crd_s, mt)
+
+        databus.tx_crd_connected(version, source_addr)
+        log.debug(util.c("[SVS] established new session: ", crd_s))
+
+        self.next_ids.crd = id + 1
 
         -- success
-        return coord_s.instance.get_id()
+        return id
     else
         -- we already have a coordinator linked
         return false
@@ -392,32 +418,41 @@ end
 
 -- establish a new pocket diagnostics session
 ---@nodiscard
----@param local_port integer
----@param remote_port integer
+---@param source_addr integer
 ---@param version string
 ---@return integer|false session_id
-function svsessions.establish_diag_session(local_port, remote_port, version)
-    ---@class diag_session_struct
-    local diag_s = {
+function svsessions.establish_pdg_session(source_addr, version)
+    ---@class pdg_session_struct
+    local pdg_s = {
         s_type = "pkt",
         open = true,
         version = version,
-        l_port = local_port,
-        r_port = remote_port,
+        r_chan = config.PKT_CHANNEL,
+        s_addr = source_addr,
         in_queue = mqueue.new(),
         out_queue = mqueue.new(),
-        instance = nil  ---@type diag_session
+        instance = nil  ---@type pdg_session
     }
 
-    diag_s.instance = pocket.new_session(self.next_ids.diag, diag_s.in_queue, diag_s.out_queue, config.PKT_TIMEOUT)
-    table.insert(self.sessions.diag, diag_s)
+    local id = self.next_ids.pdg
 
-    log.debug("established new pocket diagnostics session to " .. remote_port .. " with ID " .. self.next_ids.diag)
+    pdg_s.instance = pocket.new_session(id, source_addr, pdg_s.in_queue, pdg_s.out_queue, config.PKT_TIMEOUT, self.fp_ok)
+    table.insert(self.sessions.pdg, pdg_s)
 
-    self.next_ids.diag = self.next_ids.diag + 1
+    local mt = {
+        ---@param s pdg_session_struct
+        __tostring = function (s)  return util.c("PDG [", s.instance.get_id(), "] (@", s.s_addr, ")") end
+    }
+
+    setmetatable(pdg_s, mt)
+
+    databus.tx_pdg_connected(id, version, source_addr)
+    log.debug(util.c("[SVS] established new session: ", pdg_s))
+
+    self.next_ids.pdg = id + 1
 
     -- success
-    return diag_s.instance.get_id()
+    return id
 end
 
 -- attempt to identify which session's watchdog timer fired
@@ -449,9 +484,7 @@ end
 -- close all open connections
 function svsessions.close_all()
     -- close sessions
-    for _, list in pairs(self.sessions) do
-        _close(list)
-    end
+    for _, list in pairs(self.sessions) do _close(list) end
 
     -- free sessions
     svsessions.free_all_closed()
diff --git a/supervisor/startup.lua b/supervisor/startup.lua
index 534a5d9..687ede1 100644
--- a/supervisor/startup.lua
+++ b/supervisor/startup.lua
@@ -5,16 +5,22 @@
 require("/initenv").init_env()
 
 local crash      = require("scada-common.crash")
+local comms      = require("scada-common.comms")
 local log        = require("scada-common.log")
 local ppm        = require("scada-common.ppm")
+local tcd        = require("scada-common.tcd")
 local util       = require("scada-common.util")
 
+local core       = require("graphics.core")
+
 local config     = require("supervisor.config")
+local databus    = require("supervisor.databus")
+local renderer   = require("supervisor.renderer")
 local supervisor = require("supervisor.supervisor")
 
 local svsessions = require("supervisor.session.svsessions")
 
-local SUPERVISOR_VERSION = "v0.15.9"
+local SUPERVISOR_VERSION = "v0.17.5"
 
 local println = util.println
 local println_ts = util.println_ts
@@ -25,8 +31,11 @@ local println_ts = util.println_ts
 
 local cfv = util.new_validator()
 
-cfv.assert_port(config.SCADA_DEV_LISTEN)
-cfv.assert_port(config.SCADA_SV_CTL_LISTEN)
+cfv.assert_channel(config.SVR_CHANNEL)
+cfv.assert_channel(config.PLC_CHANNEL)
+cfv.assert_channel(config.RTU_CHANNEL)
+cfv.assert_channel(config.CRD_CHANNEL)
+cfv.assert_channel(config.PKT_CHANNEL)
 cfv.assert_type_int(config.TRUSTED_RANGE)
 cfv.assert_type_num(config.PLC_TIMEOUT)
 cfv.assert_min(config.PLC_TIMEOUT, 2)
@@ -79,6 +88,9 @@ local function main()
     -- startup
     ----------------------------------------
 
+    -- record firmware versions and ID
+    databus.tx_versions(SUPERVISOR_VERSION, comms.version)
+
     -- mount connected devices
     ppm.mount_all()
 
@@ -89,9 +101,22 @@ local function main()
         return
     end
 
-    -- start comms, open all channels
-    local superv_comms = supervisor.comms(SUPERVISOR_VERSION, config.NUM_REACTORS, config.REACTOR_COOLING, modem,
-                                            config.SCADA_DEV_LISTEN, config.SCADA_SV_CTL_LISTEN, config.TRUSTED_RANGE)
+    databus.tx_hw_modem(true)
+
+    -- start UI
+    local fp_ok, message = pcall(renderer.start_ui)
+
+    if not fp_ok then
+        renderer.close_ui()
+        println_ts(util.c("UI error: ", message))
+        log.error(util.c("GUI crashed with error ", message))
+    else
+        -- redefine println_ts local to not print as we have the front panel running
+        println_ts = function (_) end
+    end
+
+    -- start comms
+    local superv_comms = supervisor.comms(SUPERVISOR_VERSION, modem, fp_ok)
 
     -- base loop clock (6.67Hz, 3 ticks)
     local MAIN_CLOCK = 0.15
@@ -100,6 +125,9 @@ local function main()
     -- start clock
     loop_clock.start()
 
+    -- halve the rate heartbeat LED flash
+    local heartbeat_toggle = true
+
     -- event loop
     while true do
         local event, param1, param2, param3, param4, param5 = util.pull_event()
@@ -114,6 +142,7 @@ local function main()
                     if device == modem then
                         println_ts("wireless modem disconnected!")
                         log.warning("comms modem disconnected")
+                        databus.tx_hw_modem(false)
                     else
                         log.warning("non-comms modem disconnected")
                     end
@@ -131,6 +160,8 @@ local function main()
 
                         println_ts("wireless modem reconnected.")
                         log.info("comms modem reconnected")
+
+                        databus.tx_hw_modem(true)
                     else
                         log.info("wired modem reconnected")
                     end
@@ -139,6 +170,9 @@ local function main()
         elseif event == "timer" and loop_clock.is_clock(param1) then
             -- main loop tick
 
+            if heartbeat_toggle then databus.heartbeat() end
+            heartbeat_toggle = not heartbeat_toggle
+
             -- iterate sessions
             svsessions.iterate_all()
 
@@ -149,10 +183,16 @@ local function main()
         elseif event == "timer" then
             -- a non-clock timer event, check watchdogs
             svsessions.check_all_watchdogs(param1)
+
+            -- notify timer callback dispatcher
+            tcd.handle(param1)
         elseif event == "modem_message" then
             -- got a packet
             local packet = superv_comms.parse_packet(param1, param2, param3, param4, param5)
             superv_comms.handle_packet(packet)
+        elseif event == "mouse_click" or event == "mouse_up" or event == "mouse_drag" or event == "mouse_scroll" then
+            -- handle a mouse event
+            renderer.handle_mouse(core.events.new_mouse_event(event, param1, param2, param3))
         end
 
         -- check for termination request
@@ -165,8 +205,15 @@ local function main()
         end
     end
 
-    println_ts("exited")
+    renderer.close_ui()
+
+    util.println_ts("exited")
     log.info("exited")
 end
 
-if not xpcall(main, crash.handler) then crash.exit() else log.close() end
+if not xpcall(main, crash.handler) then
+    pcall(renderer.close_ui)
+    crash.exit()
+else
+    log.close()
+end
diff --git a/supervisor/supervisor.lua b/supervisor/supervisor.lua
index 998c438..cfc52d8 100644
--- a/supervisor/supervisor.lua
+++ b/supervisor/supervisor.lua
@@ -2,6 +2,8 @@ local comms      = require("scada-common.comms")
 local log        = require("scada-common.log")
 local util       = require("scada-common.util")
 
+local config     = require("supervisor.config")
+
 local svsessions = require("supervisor.session.svsessions")
 
 local supervisor = {}
@@ -11,64 +13,59 @@ local DEVICE_TYPE = comms.DEVICE_TYPE
 local ESTABLISH_ACK = comms.ESTABLISH_ACK
 local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
 
-local println = util.println
-
 -- supervisory controller communications
 ---@nodiscard
 ---@param _version string supervisor version
----@param num_reactors integer number of reactors
----@param cooling_conf table cooling configuration table
 ---@param modem table modem device
----@param dev_listen integer listening port for PLC/RTU devices
----@param svctl_listen integer listening port for supervisor access
----@param range integer trusted device connection range
+---@param fp_ok boolean if the front panel UI is running
 ---@diagnostic disable-next-line: unused-local
-function supervisor.comms(_version, num_reactors, cooling_conf, modem, dev_listen, svctl_listen, range)
+function supervisor.comms(_version, modem, fp_ok)
+    -- print a log message to the terminal as long as the UI isn't running
+    local function println(message) if not fp_ok then util.println_ts(message) end end
+
+    -- channel list from config
+    local svr_channel = config.SVR_CHANNEL
+    local plc_channel = config.PLC_CHANNEL
+    local rtu_channel = config.RTU_CHANNEL
+    local crd_channel = config.CRD_CHANNEL
+    local pkt_channel = config.PKT_CHANNEL
+
+    -- configuration data
+    local num_reactors = config.NUM_REACTORS
+    local cooling_conf = config.REACTOR_COOLING
+
     local self = {
         last_est_acks = {}
     }
 
-    comms.set_trusted_range(range)
+    comms.set_trusted_range(config.TRUSTED_RANGE)
 
     -- PRIVATE FUNCTIONS --
 
     -- configure modem channels
     local function _conf_channels()
         modem.closeAll()
-        modem.open(dev_listen)
-        modem.open(svctl_listen)
+        modem.open(svr_channel)
     end
 
     _conf_channels()
 
-    -- link modem to svsessions
-    svsessions.init(modem, num_reactors, cooling_conf)
+    -- pass modem, status, and config data to svsessions
+    svsessions.init(modem, fp_ok, num_reactors, cooling_conf)
 
-    -- send an establish request response to a PLC/RTU
-    ---@param dest integer
-    ---@param msg table
-    local function _send_dev_establish(seq_id, dest, msg)
+    -- send an establish request response
+    ---@param packet scada_packet
+    ---@param ack ESTABLISH_ACK
+    ---@param data? any optional data
+    local function _send_establish(packet, ack, data)
         local s_pkt = comms.scada_packet()
         local m_pkt = comms.mgmt_packet()
 
-        m_pkt.make(SCADA_MGMT_TYPE.ESTABLISH, msg)
-        s_pkt.make(seq_id, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
+        m_pkt.make(SCADA_MGMT_TYPE.ESTABLISH, { ack, data })
+        s_pkt.make(packet.src_addr(), packet.seq_num() + 1, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
 
-        modem.transmit(dest, dev_listen, s_pkt.raw_sendable())
-    end
-
-    -- send supervisor control access connection establish response
-    ---@param seq_id integer
-    ---@param dest integer
-    ---@param msg table
-    local function _send_svctl_establish(seq_id, dest, msg)
-        local s_pkt = comms.scada_packet()
-        local c_pkt = comms.mgmt_packet()
-
-        c_pkt.make(SCADA_MGMT_TYPE.ESTABLISH, msg)
-        s_pkt.make(seq_id, PROTOCOL.SCADA_MGMT, c_pkt.raw_sendable())
-
-        modem.transmit(dest, svctl_listen, s_pkt.raw_sendable())
+        modem.transmit(packet.remote_channel(), svr_channel, s_pkt.raw_sendable())
+        self.last_est_acks[packet.src_addr()] = ack
     end
 
     -- PUBLIC FUNCTIONS --
@@ -136,17 +133,94 @@ function supervisor.comms(_version, num_reactors, cooling_conf, modem, dev_liste
     ---@param packet modbus_frame|rplc_frame|mgmt_frame|crdn_frame|nil
     function public.handle_packet(packet)
         if packet ~= nil then
-            local l_port = packet.scada_frame.local_port()
-            local r_port = packet.scada_frame.remote_port()
+            local l_chan = packet.scada_frame.local_channel()
+            local r_chan = packet.scada_frame.remote_channel()
+            local src_addr = packet.scada_frame.src_addr()
             local protocol = packet.scada_frame.protocol()
 
-            -- device (RTU/PLC) listening channel
-            if l_port == dev_listen then
+            if l_chan ~= svr_channel then
+                log.debug("received packet on unconfigured channel " .. l_chan, true)
+            elseif r_chan == plc_channel then
+                -- look for an associated session
+                local session = svsessions.find_plc_session(src_addr)
+
+                if protocol == PROTOCOL.RPLC then
+                    ---@cast packet rplc_frame
+                    -- reactor PLC packet
+                    if session ~= nil then
+                        -- pass the packet onto the session handler
+                        session.in_queue.push_packet(packet)
+                    else
+                        -- unknown session, force a re-link
+                        log.debug("PLC_ESTABLISH: no session but not an establish, forcing relink")
+                        _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
+                    end
+                elseif protocol == PROTOCOL.SCADA_MGMT then
+                    ---@cast packet mgmt_frame
+                    -- SCADA management packet
+                    if session ~= nil then
+                        -- pass the packet onto the session handler
+                        session.in_queue.push_packet(packet)
+                    elseif packet.type == SCADA_MGMT_TYPE.ESTABLISH then
+                        -- establish a new session
+                        local last_ack = self.last_est_acks[src_addr]
+
+                        -- validate packet and continue
+                        if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
+                            local comms_v    = packet.data[1]
+                            local firmware_v = packet.data[2]
+                            local dev_type   = packet.data[3]
+
+                            if comms_v ~= comms.version then
+                                if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                                    log.info(util.c("dropping PLC establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
+                                end
+
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
+                            elseif dev_type == DEVICE_TYPE.PLC then
+                                -- PLC linking request
+                                if packet.length == 4 and type(packet.data[4]) == "number" then
+                                    local reactor_id = packet.data[4]
+                                    local plc_id = svsessions.establish_plc_session(src_addr, reactor_id, firmware_v)
+
+                                    if plc_id == false then
+                                        -- reactor already has a PLC assigned
+                                        if last_ack ~= ESTABLISH_ACK.COLLISION then
+                                            log.warning(util.c("PLC_ESTABLISH: assignment collision with reactor ", reactor_id))
+                                        end
+
+                                        _send_establish(packet.scada_frame, ESTABLISH_ACK.COLLISION)
+                                    else
+                                        -- got an ID; assigned to a reactor successfully
+                                        println(util.c("PLC (", firmware_v, ") [@", src_addr, "] \xbb reactor ", reactor_id, " connected"))
+                                        log.info(util.c("PLC_ESTABLISH: PLC (", firmware_v, ") [@", src_addr, "] reactor unit ", reactor_id, " PLC connected with session ID ", plc_id))
+                                        _send_establish(packet.scada_frame, ESTABLISH_ACK.ALLOW)
+                                    end
+                                else
+                                    log.debug("PLC_ESTABLISH: packet length mismatch/bad parameter type")
+                                    _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
+                                end
+                            else
+                                log.debug(util.c("illegal establish packet for device ", dev_type, " on PLC channel"))
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
+                            end
+                        else
+                            log.debug("invalid establish packet (on PLC channel)")
+                            _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
+                        end
+                    else
+                        -- any other packet should be session related, discard it
+                        log.debug(util.c("discarding PLC SCADA_MGMT packet without a known session from computer ", src_addr))
+                    end
+                else
+                    log.debug(util.c("illegal packet type ", protocol, " on PLC channel"))
+                end
+            elseif r_chan == rtu_channel then
+                -- look for an associated session
+                local session = svsessions.find_rtu_session(src_addr)
+
                 if protocol == PROTOCOL.MODBUS_TCP then
                     ---@cast packet modbus_frame
-                    -- look for an associated session
-                    local session = svsessions.find_rtu_session(r_port)
-
                     -- MODBUS response
                     if session ~= nil then
                         -- pass the packet onto the session handler
@@ -155,105 +229,59 @@ function supervisor.comms(_version, num_reactors, cooling_conf, modem, dev_liste
                         -- any other packet should be session related, discard it
                         log.debug("discarding MODBUS_TCP packet without a known session")
                     end
-                elseif protocol == PROTOCOL.RPLC then
-                    ---@cast packet rplc_frame
-                    -- look for an associated session
-                    local session = svsessions.find_plc_session(r_port)
-
-                    -- reactor PLC packet
-                    if session ~= nil then
-                        -- pass the packet onto the session handler
-                        session.in_queue.push_packet(packet)
-                    else
-                        -- unknown session, force a re-link
-                        log.debug("PLC_ESTABLISH: no session but not an establish, forcing relink")
-                        _send_dev_establish(packet.scada_frame.seq_num() + 1, r_port, { ESTABLISH_ACK.DENY })
-                    end
                 elseif protocol == PROTOCOL.SCADA_MGMT then
                     ---@cast packet mgmt_frame
-                    -- look for an associated session
-                    local session = svsessions.find_device_session(r_port)
-
                     -- SCADA management packet
                     if session ~= nil then
                         -- pass the packet onto the session handler
                         session.in_queue.push_packet(packet)
                     elseif packet.type == SCADA_MGMT_TYPE.ESTABLISH then
                         -- establish a new session
-                        local next_seq_id = packet.scada_frame.seq_num() + 1
+                        local last_ack = self.last_est_acks[src_addr]
 
                         -- validate packet and continue
                         if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
-                            local comms_v = packet.data[1]
+                            local comms_v    = packet.data[1]
                             local firmware_v = packet.data[2]
-                            local dev_type = packet.data[3]
+                            local dev_type   = packet.data[3]
 
                             if comms_v ~= comms.version then
-                                if self.last_est_acks[r_port] ~= ESTABLISH_ACK.BAD_VERSION then
-                                    log.info(util.c("dropping device establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                                    self.last_est_acks[r_port] = ESTABLISH_ACK.BAD_VERSION
+                                if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                                    log.info(util.c("dropping RTU establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
                                 end
 
-                                _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.BAD_VERSION })
-                            elseif dev_type == DEVICE_TYPE.PLC then
-                                -- PLC linking request
-                                if packet.length == 4 and type(packet.data[4]) == "number" then
-                                    local reactor_id = packet.data[4]
-                                    local plc_id = svsessions.establish_plc_session(l_port, r_port, reactor_id, firmware_v)
-
-                                    if plc_id == false then
-                                        -- reactor already has a PLC assigned
-                                        if self.last_est_acks[r_port] ~= ESTABLISH_ACK.COLLISION then
-                                            log.warning(util.c("PLC_ESTABLISH: assignment collision with reactor ", reactor_id))
-                                            self.last_est_acks[r_port] = ESTABLISH_ACK.COLLISION
-                                        end
-
-                                        _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.COLLISION })
-                                    else
-                                        -- got an ID; assigned to a reactor successfully
-                                        println(util.c("PLC (", firmware_v, ") [:", r_port, "] \xbb reactor ", reactor_id, " connected"))
-                                        log.info(util.c("PLC_ESTABLISH: PLC (", firmware_v, ") [:", r_port, "] reactor unit ", reactor_id, " PLC connected with session ID ", plc_id))
-
-                                        _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.ALLOW })
-                                        self.last_est_acks[r_port] = ESTABLISH_ACK.ALLOW
-                                    end
-                                else
-                                    log.debug("PLC_ESTABLISH: packet length mismatch/bad parameter type")
-                                    _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
-                                end
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
                             elseif dev_type == DEVICE_TYPE.RTU then
                                 if packet.length == 4 then
                                     -- this is an RTU advertisement for a new session
                                     local rtu_advert = packet.data[4]
-                                    local s_id = svsessions.establish_rtu_session(l_port, r_port, rtu_advert, firmware_v)
+                                    local s_id = svsessions.establish_rtu_session(src_addr, rtu_advert, firmware_v)
 
-                                    println(util.c("RTU (", firmware_v, ") [:", r_port, "] \xbb connected"))
-                                    log.info(util.c("RTU_ESTABLISH: RTU (",firmware_v, ") [:", r_port, "] connected with session ID ", s_id))
-
-                                    _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.ALLOW })
+                                    println(util.c("RTU (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+                                    log.info(util.c("RTU_ESTABLISH: RTU (",firmware_v, ") [@", src_addr, "] connected with session ID ", s_id))
+                                    _send_establish(packet.scada_frame, ESTABLISH_ACK.ALLOW)
                                 else
                                     log.debug("RTU_ESTABLISH: packet length mismatch")
-                                    _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                                    _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
                                 end
                             else
-                                log.debug(util.c("illegal establish packet for device ", dev_type, " on PLC/RTU listening channel"))
-                                _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                                log.debug(util.c("illegal establish packet for device ", dev_type, " on RTU channel"))
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
                             end
                         else
-                            log.debug("invalid establish packet (on PLC/RTU listening channel)")
-                            _send_dev_establish(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                            log.debug("invalid establish packet (on RTU channel)")
+                            _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
                         end
                     else
                         -- any other packet should be session related, discard it
-                        log.debug(util.c(r_port, "->", l_port, ": discarding SCADA_MGMT packet without a known session"))
+                        log.debug(util.c("discarding RTU SCADA_MGMT packet without a known session from computer ", src_addr))
                     end
                 else
-                    log.debug("illegal packet type " .. protocol .. " on device listening channel")
+                    log.debug(util.c("illegal packet type ", protocol, " on RTU channel"))
                 end
-            -- coordinator listening channel
-            elseif l_port == svctl_listen then
+            elseif r_chan == crd_channel then
                 -- look for an associated session
-                local session = svsessions.find_svctl_session(r_port)
+                local session = svsessions.find_crd_session(src_addr)
 
                 if protocol == PROTOCOL.SCADA_MGMT then
                     ---@cast packet mgmt_frame
@@ -263,65 +291,53 @@ function supervisor.comms(_version, num_reactors, cooling_conf, modem, dev_liste
                         session.in_queue.push_packet(packet)
                     elseif packet.type == SCADA_MGMT_TYPE.ESTABLISH then
                         -- establish a new session
-                        local next_seq_id = packet.scada_frame.seq_num() + 1
+                        local last_ack = self.last_est_acks[src_addr]
 
                         -- validate packet and continue
                         if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
-                            local comms_v = packet.data[1]
+                            local comms_v    = packet.data[1]
                             local firmware_v = packet.data[2]
-                            local dev_type = packet.data[3]
+                            local dev_type   = packet.data[3]
 
                             if comms_v ~= comms.version then
-                                if self.last_est_acks[r_port] ~= ESTABLISH_ACK.BAD_VERSION then
+                                if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
                                     log.info(util.c("dropping coordinator establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
-                                    self.last_est_acks[r_port] = ESTABLISH_ACK.BAD_VERSION
                                 end
 
-                                _send_svctl_establish(next_seq_id, r_port, { ESTABLISH_ACK.BAD_VERSION })
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
                             elseif dev_type == DEVICE_TYPE.CRDN then
                                 -- this is an attempt to establish a new coordinator session
-                                local s_id = svsessions.establish_coord_session(l_port, r_port, firmware_v)
+                                local s_id = svsessions.establish_crd_session(src_addr, firmware_v)
 
                                 if s_id ~= false then
-                                    local config = { num_reactors }
+                                    local cfg = { num_reactors }
                                     for i = 1, #cooling_conf do
-                                        table.insert(config, cooling_conf[i].BOILERS)
-                                        table.insert(config, cooling_conf[i].TURBINES)
+                                        table.insert(cfg, cooling_conf[i].BOILERS)
+                                        table.insert(cfg, cooling_conf[i].TURBINES)
                                     end
 
-                                    println(util.c("CRD (", firmware_v, ") [:", r_port, "] \xbb connected"))
-                                    log.info(util.c("SVCTL_ESTABLISH: coordinator (", firmware_v, ") [:", r_port, "] connected with session ID ", s_id))
+                                    println(util.c("CRD (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+                                    log.info(util.c("CRD_ESTABLISH: coordinator (", firmware_v, ") [@", src_addr, "] connected with session ID ", s_id))
 
-                                    _send_svctl_establish(next_seq_id, r_port, { ESTABLISH_ACK.ALLOW, config })
-                                    self.last_est_acks[r_port] = ESTABLISH_ACK.ALLOW
+                                    _send_establish(packet.scada_frame, ESTABLISH_ACK.ALLOW, cfg)
                                 else
-                                    if self.last_est_acks[r_port] ~= ESTABLISH_ACK.COLLISION then
-                                        log.info("SVCTL_ESTABLISH: denied new coordinator due to already being connected to another coordinator")
-                                        self.last_est_acks[r_port] = ESTABLISH_ACK.COLLISION
+                                    if last_ack ~= ESTABLISH_ACK.COLLISION then
+                                        log.info("CRD_ESTABLISH: denied new coordinator [@" .. src_addr .. "] due to already being connected to another coordinator")
                                     end
 
-                                    _send_svctl_establish(next_seq_id, r_port, { ESTABLISH_ACK.COLLISION })
+                                    _send_establish(packet.scada_frame, ESTABLISH_ACK.COLLISION)
                                 end
-                            elseif dev_type == DEVICE_TYPE.PKT then
-                                -- this is an attempt to establish a new pocket diagnostic session
-                                local s_id = svsessions.establish_diag_session(l_port, r_port, firmware_v)
-
-                                println(util.c("PKT (", firmware_v, ") [:", r_port, "] \xbb connected"))
-                                log.info(util.c("SVCTL_ESTABLISH: pocket (", firmware_v, ") [:", r_port, "] connected with session ID ", s_id))
-
-                                _send_svctl_establish(next_seq_id, r_port, { ESTABLISH_ACK.ALLOW })
-                                self.last_est_acks[r_port] = ESTABLISH_ACK.ALLOW
                             else
-                                log.debug(util.c("illegal establish packet for device ", dev_type, " on SVCTL listening channel"))
-                                _send_svctl_establish(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                                log.debug(util.c("illegal establish packet for device ", dev_type, " on coordinator channel"))
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
                             end
                         else
-                            log.debug("SVCTL_ESTABLISH: establish packet length mismatch")
-                            _send_svctl_establish(next_seq_id, r_port, { ESTABLISH_ACK.DENY })
+                            log.debug("CRD_ESTABLISH: establish packet length mismatch")
+                            _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
                         end
                     else
                         -- any other packet should be session related, discard it
-                        log.debug(r_port .. "->" .. l_port .. ": discarding SCADA_MGMT packet without a known session")
+                        log.debug(util.c("discarding coordinator SCADA_MGMT packet without a known session from computer ", src_addr))
                     end
                 elseif protocol == PROTOCOL.SCADA_CRDN then
                     ---@cast packet crdn_frame
@@ -331,13 +347,72 @@ function supervisor.comms(_version, num_reactors, cooling_conf, modem, dev_liste
                         session.in_queue.push_packet(packet)
                     else
                         -- any other packet should be session related, discard it
-                        log.debug(r_port .. "->" .. l_port .. ": discarding SCADA_CRDN packet without a known session")
+                        log.debug(util.c("discarding coordinator SCADA_CRDN packet without a known session from computer ", src_addr))
                     end
                 else
-                    log.debug("illegal packet type " .. protocol .. " on coordinator listening channel")
+                    log.debug(util.c("illegal packet type ", protocol, " on coordinator channel"))
+                end
+            elseif r_chan == pkt_channel then
+                -- look for an associated session
+                local session = svsessions.find_pdg_session(src_addr)
+
+                if protocol == PROTOCOL.SCADA_MGMT then
+                    ---@cast packet mgmt_frame
+                    -- SCADA management packet
+                    if session ~= nil then
+                        -- pass the packet onto the session handler
+                        session.in_queue.push_packet(packet)
+                    elseif packet.type == SCADA_MGMT_TYPE.ESTABLISH then
+                        -- establish a new session
+                        local last_ack = self.last_est_acks[src_addr]
+
+                        -- validate packet and continue
+                        if packet.length >= 3 and type(packet.data[1]) == "string" and type(packet.data[2]) == "string" then
+                            local comms_v    = packet.data[1]
+                            local firmware_v = packet.data[2]
+                            local dev_type   = packet.data[3]
+
+                            if comms_v ~= comms.version then
+                                if last_ack ~= ESTABLISH_ACK.BAD_VERSION then
+                                    log.info(util.c("dropping PDG establish packet with incorrect comms version v", comms_v, " (expected v", comms.version, ")"))
+                                end
+
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.BAD_VERSION)
+                            elseif dev_type == DEVICE_TYPE.PKT then
+                                -- this is an attempt to establish a new pocket diagnostic session
+                                local s_id = svsessions.establish_pdg_session(src_addr, firmware_v)
+
+                                println(util.c("PKT (", firmware_v, ") [@", src_addr, "] \xbb connected"))
+                                log.info(util.c("PDG_ESTABLISH: pocket (", firmware_v, ") [@", src_addr, "] connected with session ID ", s_id))
+
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.ALLOW)
+                            else
+                                log.debug(util.c("illegal establish packet for device ", dev_type, " on pocket channel"))
+                                _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
+                            end
+                        else
+                            log.debug("PDG_ESTABLISH: establish packet length mismatch")
+                            _send_establish(packet.scada_frame, ESTABLISH_ACK.DENY)
+                        end
+                    else
+                        -- any other packet should be session related, discard it
+                        log.debug(util.c("discarding pocket SCADA_MGMT packet without a known session from computer ", src_addr))
+                    end
+                elseif protocol == PROTOCOL.SCADA_CRDN then
+                    ---@cast packet crdn_frame
+                    -- coordinator packet
+                    if session ~= nil then
+                        -- pass the packet onto the session handler
+                        session.in_queue.push_packet(packet)
+                    else
+                        -- any other packet should be session related, discard it
+                        log.debug(util.c("discarding pocket SCADA_CRDN packet without a known session from computer ", src_addr))
+                    end
+                else
+                    log.debug(util.c("illegal packet type ", protocol, " on pocket channel"))
                 end
             else
-                log.debug("received packet on unconfigured channel " .. l_port, true)
+                log.debug("received packet for unknown channel " .. r_chan, true)
             end
         end
     end
diff --git a/supervisor/unit.lua b/supervisor/unit.lua
index 0cccc48..0d7246a 100644
--- a/supervisor/unit.lua
+++ b/supervisor/unit.lua
@@ -506,7 +506,7 @@ function unit.new(reactor_id, num_boilers, num_turbines)
     --#region
 
     -- engage automatic control
-    function public.a_engage()
+    function public.auto_engage()
         self.auto_engaged = true
         if self.plc_i ~= nil then
             self.plc_i.auto_lock(true)
@@ -514,7 +514,7 @@ function unit.new(reactor_id, num_boilers, num_turbines)
     end
 
     -- disengage automatic control
-    function public.a_disengage()
+    function public.auto_disengage()
         self.auto_engaged = false
         if self.plc_i ~= nil then
             self.plc_i.auto_lock(false)
@@ -526,7 +526,7 @@ function unit.new(reactor_id, num_boilers, num_turbines)
     -- if it is degraded or not ready, the limit will be 0
     ---@nodiscard
     ---@return integer lim_br100
-    function public.a_get_effective_limit()
+    function public.auto_get_effective_limit()
         if (not self.db.control.ready) or self.db.control.degraded or self.plc_cache.rps_trip then
             self.db.control.br100 = 0
             return 0
@@ -537,7 +537,7 @@ function unit.new(reactor_id, num_boilers, num_turbines)
 
     -- set the automatic burn rate based on the last set burn rate in 100ths
     ---@param ramp boolean true to ramp to rate, false to set right away
-    function public.a_commit_br100(ramp)
+    function public.auto_commit_br100(ramp)
         if self.auto_engaged then
             if self.plc_i ~= nil then
                 self.plc_i.auto_set_burn(self.db.control.br100 / 100, ramp)
@@ -550,16 +550,16 @@ function unit.new(reactor_id, num_boilers, num_turbines)
     -- check if ramping is complete (burn rate is same as target)
     ---@nodiscard
     ---@return boolean complete
-    function public.a_ramp_complete()
+    function public.auto_ramp_complete()
         if self.plc_i ~= nil then
             return self.plc_i.is_ramp_complete() or
                 (self.plc_i.get_status().act_burn_rate == 0 and self.db.control.br100 == 0) or
-                public.a_get_effective_limit() == 0
+                public.auto_get_effective_limit() == 0
         else return true end
     end
 
     -- perform an automatic SCRAM
-    function public.a_scram()
+    function public.auto_scram()
         if self.plc_s ~= nil then
             self.db.control.br100 = 0
             self.plc_s.in_queue.push_command(PLC_S_CMDS.ASCRAM)
@@ -567,7 +567,7 @@ function unit.new(reactor_id, num_boilers, num_turbines)
     end
 
     -- queue a command to clear timeout/auto-scram if set
-    function public.a_cond_rps_reset()
+    function public.auto_cond_rps_reset()
         if self.plc_s ~= nil and self.plc_i ~= nil and (not self.auto_was_alarmed) and (not self.emcool_opened) then
             local rps = self.plc_i.get_rps()
             if rps.timeout or rps.automatic then
diff --git a/supervisor/unitlogic.lua b/supervisor/unitlogic.lua
index ca97181..fab67f3 100644
--- a/supervisor/unitlogic.lua
+++ b/supervisor/unitlogic.lua
@@ -549,7 +549,7 @@ function logic.update_auto_safety(public, self)
         end
 
         if alarmed and not self.plc_cache.rps_status.automatic then
-            public.a_scram()
+            public.auto_scram()
         end
 
         self.auto_was_alarmed = alarmed
diff --git a/test/lockbox-benchmark.lua b/test/lockbox-benchmark.lua
index 198f41b..7c6ae55 100644
--- a/test/lockbox-benchmark.lua
+++ b/test/lockbox-benchmark.lua
@@ -38,7 +38,7 @@ local pkt = comms.modbus_packet()
 ---@diagnostic disable-next-line: param-type-mismatch
 pkt.make(1, 2, 7, {0, 1, 2, 3, 4, 5, 6, 7, 8, 9})
 local spkt = comms.scada_packet()
-spkt.make(1, 1, pkt.raw_sendable())
+spkt.make(0, 1, 1, pkt.raw_sendable())
 
 start = util.time()
 local data = textutils.serialize(spkt.raw_sendable(), { allow_repetitions = true, compact = true })