diff --git a/reactor-plc/panel/front_panel.lua b/reactor-plc/panel/front_panel.lua
index 8e28a75..a8675a0 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)
diff --git a/reactor-plc/plc.lua b/reactor-plc/plc.lua
index a4f66dc..0d13091 100644
--- a/reactor-plc/plc.lua
+++ b/reactor-plc/plc.lua
@@ -672,6 +672,7 @@ function plc.comms(id, version, modem, plc_channel, svr_channel, range, reactor,
         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
diff --git a/reactor-plc/startup.lua b/reactor-plc/startup.lua
index 682e618..b5a2e3b 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 = "v1.4.0"
+local R_PLC_VERSION = "v1.4.1"
 
 local println = util.println
 local println_ts = util.println_ts
diff --git a/rtu/panel/front_panel.lua b/rtu/panel/front_panel.lua
index 606abbb..09270e9 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)
diff --git a/rtu/rtu.lua b/rtu/rtu.lua
index c89dabb..5d2e2c8 100644
--- a/rtu/rtu.lua
+++ b/rtu/rtu.lua
@@ -257,6 +257,7 @@ function rtu.comms(version, modem, rtu_channel, svr_channel, range, conn_watchdo
         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
diff --git a/rtu/startup.lua b/rtu/startup.lua
index 020c2aa..d37be78 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 = "v1.3.1"
 
 local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 local RTU_UNIT_HW_STATE = databus.RTU_UNIT_HW_STATE
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