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= 2) before assuming a remote device is no longer active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 55c6356..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
 
@@ -436,15 +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
@@ -457,7 +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
@@ -465,8 +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]
@@ -474,42 +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
@@ -660,6 +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
@@ -705,10 +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)
 
@@ -719,7 +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
@@ -732,7 +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 4ba7383..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
@@ -134,11 +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
@@ -171,7 +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
 
@@ -210,7 +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
@@ -246,4 +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 4a08166..5d4fec8 100644
--- a/coordinator/startup.lua
+++ b/coordinator/startup.lua
@@ -20,7 +20,7 @@ local sounder     = require("coordinator.sounder")
 
 local apisessions = require("coordinator.session.apisessions")
 
-local COORDINATOR_VERSION = "v0.15.8"
+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
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 32d4737..0683af6 100644
--- a/pocket/startup.lua
+++ b/pocket/startup.lua
@@ -17,7 +17,7 @@ local coreio   = require("pocket.coreio")
 local pocket   = require("pocket.pocket")
 local renderer = require("pocket.renderer")
 
-local POCKET_VERSION = "alpha-v0.3.7"
+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)
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 812ed45..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 = "v1.3.7"
+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/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 606abbb..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")
@@ -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 4cb90ac..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 = "v1.2.8"
+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)
@@ -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/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/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
index a1e947e..00185c7 100644
--- a/supervisor/databus.lua
+++ b/supervisor/databus.lua
@@ -3,9 +3,14 @@
 --
 
 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
@@ -31,11 +36,11 @@ end
 -- transmit PLC firmware version and session connection state
 ---@param reactor_id integer reactor unit ID
 ---@param fw string firmware version
----@param channel integer PLC remote port
-function databus.tx_plc_connected(reactor_id, fw, channel)
+---@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 .. "_chan", tostring(channel))
+    databus.ps.publish("plc_" .. reactor_id .. "_addr", util.sprintf("@% 4d", s_addr))
 end
 
 -- transmit PLC disconnected
@@ -43,7 +48,7 @@ end
 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 .. "_chan", " --- ")
+    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
@@ -54,9 +59,9 @@ end
 function databus.tx_plc_rtt(reactor_id, rtt)
     databus.ps.publish("plc_" .. reactor_id .. "_rtt", rtt)
 
-    if rtt > 700 then
+    if rtt > HIGH_RTT then
         databus.ps.publish("plc_" .. reactor_id .. "_rtt_color", colors.red)
-    elseif rtt > 300 then
+    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)
@@ -66,10 +71,10 @@ end
 -- transmit RTU firmware version and session connection state
 ---@param session_id integer RTU session
 ---@param fw string firmware version
----@param channel integer RTU remote port
-function databus.tx_rtu_connected(session_id, fw, channel)
+---@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 .. "_chan", tostring(channel))
+    databus.ps.publish("rtu_" .. session_id .. "_addr", util.sprintf("@ C% 3d", s_addr))
     pgi.create_rtu_entry(session_id)
 end
 
@@ -85,9 +90,9 @@ end
 function databus.tx_rtu_rtt(session_id, rtt)
     databus.ps.publish("rtu_" .. session_id .. "_rtt", rtt)
 
-    if rtt > 700 then
+    if rtt > HIGH_RTT then
         databus.ps.publish("rtu_" .. session_id .. "_rtt_color", colors.red)
-    elseif rtt > 300 then
+    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)
@@ -103,18 +108,18 @@ end
 
 -- transmit coordinator firmware version and session connection state
 ---@param fw string firmware version
----@param channel integer coordinator remote port
-function databus.tx_crd_connected(fw, channel)
+---@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_chan", tostring(channel))
+    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_chan", "---")
+    databus.ps.publish("crd_addr", "---")
     databus.ps.publish("crd_rtt", 0)
     databus.ps.publish("crd_rtt_color", colors.lightGray)
 end
@@ -124,9 +129,9 @@ end
 function databus.tx_crd_rtt(rtt)
     databus.ps.publish("crd_rtt", rtt)
 
-    if rtt > 700 then
+    if rtt > HIGH_RTT then
         databus.ps.publish("crd_rtt_color", colors.red)
-    elseif rtt > 300 then
+    elseif rtt > WARN_RTT then
         databus.ps.publish("crd_rtt_color", colors.yellow_hc)
     else
         databus.ps.publish("crd_rtt_color", colors.green)
@@ -136,10 +141,10 @@ end
 -- transmit PKT firmware version and PDG session connection state
 ---@param session_id integer PDG session
 ---@param fw string firmware version
----@param channel integer PDG remote port
-function databus.tx_pdg_connected(session_id, fw, channel)
+---@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 .. "_chan", tostring(channel))
+    databus.ps.publish("pdg_" .. session_id .. "_addr", util.sprintf("@ C% 3d", s_addr))
     pgi.create_pdg_entry(session_id)
 end
 
@@ -155,9 +160,9 @@ end
 function databus.tx_pdg_rtt(session_id, rtt)
     databus.ps.publish("pdg_" .. session_id .. "_rtt", rtt)
 
-    if rtt > 700 then
+    if rtt > HIGH_RTT then
         databus.ps.publish("pdg_" .. session_id .. "_rtt_color", colors.red)
-    elseif rtt > 300 then
+    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)
diff --git a/supervisor/panel/components/pdg_entry.lua b/supervisor/panel/components/pdg_entry.lua
index 94cd385..1e49fca 100644
--- a/supervisor/panel/components/pdg_entry.lua
+++ b/supervisor/panel/components/pdg_entry.lua
@@ -2,8 +2,6 @@
 -- Pocket Diagnostics Connection Entry
 --
 
-local util          = require("scada-common.util")
-
 local databus       = require("supervisor.databus")
 
 local core          = require("graphics.core")
@@ -28,9 +26,9 @@ local function init(parent, id)
     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_chan = TextBox{parent=entry,x=1,y=2,text=" :00000",alignment=TEXT_ALIGN.CENTER,width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray),nav_active=cpair(colors.gray,colors.black)}
+    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_chan.register(databus.ps, ps_prefix .. "chan", function (channel) pdg_chan.set_value(util.sprintf(" :%05d", channel)) end)
+    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)}
diff --git a/supervisor/panel/components/rtu_entry.lua b/supervisor/panel/components/rtu_entry.lua
index a4a5a4e..d9634e9 100644
--- a/supervisor/panel/components/rtu_entry.lua
+++ b/supervisor/panel/components/rtu_entry.lua
@@ -2,8 +2,6 @@
 -- RTU Connection Entry
 --
 
-local util          = require("scada-common.util")
-
 local databus       = require("supervisor.databus")
 
 local core          = require("graphics.core")
@@ -28,9 +26,9 @@ local function init(parent, id)
     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_chan = TextBox{parent=entry,x=1,y=2,text=" :00000",alignment=TEXT_ALIGN.CENTER,width=8,height=1,fg_bg=cpair(colors.black,colors.lightGray),nav_active=cpair(colors.gray,colors.black)}
+    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_chan.register(databus.ps, ps_prefix .. "chan", function (channel) rtu_chan.set_value(util.sprintf(" :%05d", channel)) end)
+    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)}
diff --git a/supervisor/panel/front_panel.lua b/supervisor/panel/front_panel.lua
index 8cdcf76..b6ee692 100644
--- a/supervisor/panel/front_panel.lua
+++ b/supervisor/panel/front_panel.lua
@@ -56,6 +56,10 @@ local function init(panel)
 
     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
     --
@@ -84,11 +88,11 @@ local function init(panel)
         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="CONN",colors=cpair(colors.green,colors.green_off)}
+        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_chan = TextBox{parent=plc_entry,x=17,y=2,text=" --- ",width=5,height=1,fg_bg=cpair(colors.gray,colors.white)}
-        plc_chan.register(databus.ps, ps_prefix .. "chan", plc_chan.set_value)
+        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)}
@@ -117,9 +121,9 @@ local function init(panel)
     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="CHANNEL ",width=8,height=1,fg_bg=cpair(colors.gray,colors.white)}
-    local crd_chan = TextBox{parent=crd_box,x=12,y=3,text="---",width=5,height=1,fg_bg=cpair(colors.gray,colors.white)}
-    crd_chan.register(databus.ps, "crd_chan", crd_chan.set_value)
+    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)}
diff --git a/supervisor/session/coordinator.lua b/supervisor/session/coordinator.lua
index 36a5241..1b75078 100644
--- a/supervisor/session/coordinator.lua
+++ b/supervisor/session/coordinator.lua
@@ -45,12 +45,13 @@ 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
 ---@param fp_ok boolean if the front panel UI is running
-function coordinator.new_session(id, in_queue, out_queue, timeout, facility, fp_ok)
+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
 
@@ -99,7 +100,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility, fp_
         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
@@ -113,7 +114,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility, fp_
         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
@@ -334,7 +335,7 @@ function coordinator.new_session(id, in_queue, out_queue, timeout, facility, fp_
         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 1436534..ac80ea6 100644
--- a/supervisor/session/plc.lua
+++ b/supervisor/session/plc.lua
@@ -45,12 +45,13 @@ 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
 ---@param fp_ok boolean if the front panel UI is running
-function plc.new_session(id, reactor_id, in_queue, out_queue, timeout, fp_ok)
+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
 
@@ -250,7 +251,7 @@ function plc.new_session(id, reactor_id, in_queue, out_queue, timeout, fp_ok)
         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
@@ -264,7 +265,7 @@ function plc.new_session(id, reactor_id, in_queue, out_queue, timeout, fp_ok)
         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
diff --git a/supervisor/session/pocket.lua b/supervisor/session/pocket.lua
index ba6d179..9de55ab 100644
--- a/supervisor/session/pocket.lua
+++ b/supervisor/session/pocket.lua
@@ -29,11 +29,12 @@ 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
 ---@param fp_ok boolean if the front panel UI is running
-function pocket.new_session(id, in_queue, out_queue, timeout, fp_ok)
+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
 
@@ -81,7 +82,7 @@ function pocket.new_session(id, in_queue, out_queue, timeout, fp_ok)
         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
diff --git a/supervisor/session/rtu.lua b/supervisor/session/rtu.lua
index 2f7091c..d1fbaec 100644
--- a/supervisor/session/rtu.lua
+++ b/supervisor/session/rtu.lua
@@ -31,13 +31,14 @@ 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
 ---@param fp_ok boolean if the front panel UI is running
-function rtu.new_session(id, in_queue, out_queue, timeout, advertisement, facility, fp_ok)
+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
 
@@ -204,7 +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
@@ -218,7 +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
diff --git a/supervisor/session/svsessions.lua b/supervisor/session/svsessions.lua
index 5d22e3d..a311ab9 100644
--- a/supervisor/session/svsessions.lua
+++ b/supervisor/session/svsessions.lua
@@ -27,7 +27,7 @@ local svsessions = {}
 local SESSION_TYPE = {
     RTU_SESSION = 0,    -- RTU gateway
     PLC_SESSION = 1,    -- reactor PLC
-    COORD_SESSION = 2,  -- coordinator
+    CRD_SESSION = 2,    -- coordinator
     PDG_SESSION = 3     -- pocket diagnostics
 }
 
@@ -38,11 +38,11 @@ local self = {
     fp_ok = false,
     num_reactors = 0,
     facility = nil,     ---@type facility|nil
-    sessions = { rtu = {}, plc = {}, coord = {}, pdg = {} },
-    next_ids = { rtu = 0, plc = 0, coord = 0, pdg = 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|pdg_session_struct
+---@alias sv_session_structs plc_session_struct|rtu_session_struct|crd_session_struct|pdg_session_struct
 
 -- PRIVATE FUNCTIONS --
 
@@ -60,7 +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
@@ -81,11 +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
@@ -104,8 +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
@@ -131,15 +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
@@ -160,8 +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
@@ -175,21 +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
@@ -214,63 +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|pdg_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.pdg, remote_port) end
-    ---@cast session coord_session_struct|pdg_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
@@ -291,12 +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 = {
@@ -304,26 +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, self.fp_ok)
+        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
+        }
 
-        databus.tx_plc_connected(for_reactor, version, remote_port)
+        setmetatable(plc_s, mt)
 
-        self.next_ids.plc = self.next_ids.plc + 1
+        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()
@@ -335,70 +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, self.fp_ok)
+    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
+    }
 
-    databus.tx_rtu_connected(self.next_ids.rtu, version, remote_port)
+    setmetatable(rtu_s, mt)
 
-    self.next_ids.rtu = self.next_ids.rtu + 1
+    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,
+        local id = self.next_ids.crd
+
+        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.coord, coord_s)
+        table.insert(self.sessions.crd, crd_s)
 
-        log.debug("established new coordinator session to " .. remote_port .. " with ID " .. self.next_ids.coord)
+        local mt = {
+            ---@param s crd_session_struct
+            __tostring = function (s)  return util.c("CRD [", s.instance.get_id(), "] (@", s.s_addr, ")") end
+        }
 
-        databus.tx_crd_connected(version, remote_port)
+        setmetatable(crd_s, mt)
 
-        self.next_ids.coord = self.next_ids.coord + 1
+        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
@@ -407,34 +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_pdg_session(local_port, remote_port, version)
+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 pdg_session
     }
 
-    pdg_s.instance = pocket.new_session(self.next_ids.pdg, pdg_s.in_queue, pdg_s.out_queue, config.PKT_TIMEOUT, self.fp_ok)
+    local id = self.next_ids.pdg
+
+    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)
 
-    log.debug("established new pocket diagnostics session to " .. remote_port .. " with ID " .. self.next_ids.pdg)
+    local mt = {
+        ---@param s pdg_session_struct
+        __tostring = function (s)  return util.c("PDG [", s.instance.get_id(), "] (@", s.s_addr, ")") end
+    }
 
-    databus.tx_pdg_connected(self.next_ids.pdg, version, remote_port)
+    setmetatable(pdg_s, mt)
 
-    self.next_ids.pdg = self.next_ids.pdg + 1
+    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 pdg_s.instance.get_id()
+    return id
 end
 
 -- attempt to identify which session's watchdog timer fired
@@ -466,9 +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 ff4a4fe..687ede1 100644
--- a/supervisor/startup.lua
+++ b/supervisor/startup.lua
@@ -20,7 +20,7 @@ local supervisor = require("supervisor.supervisor")
 
 local svsessions = require("supervisor.session.svsessions")
 
-local SUPERVISOR_VERSION = "v0.16.8"
+local SUPERVISOR_VERSION = "v0.17.5"
 
 local println = util.println
 local println_ts = util.println_ts
@@ -31,8 +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)
@@ -112,9 +115,8 @@ local function main()
         println_ts = function (_) end
     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, fp_ok)
+    -- start comms
+    local superv_comms = supervisor.comms(SUPERVISOR_VERSION, modem, fp_ok)
 
     -- base loop clock (6.67Hz, 3 ticks)
     local MAIN_CLOCK = 0.15
diff --git a/supervisor/supervisor.lua b/supervisor/supervisor.lua
index 874aaa9..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 = {}
@@ -14,31 +16,36 @@ local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
 -- 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, fp_ok)
+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()
@@ -46,31 +53,19 @@ function supervisor.comms(_version, num_reactors, cooling_conf, modem, dev_liste
     -- 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 --
@@ -138,17 +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
@@ -157,105 +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
@@ -265,65 +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_pdg_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
@@ -333,13 +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/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 })