diff --git a/reactor-plc/databus.lua b/reactor-plc/databus.lua
index beee265..ba7a68e 100644
--- a/reactor-plc/databus.lua
+++ b/reactor-plc/databus.lua
@@ -8,14 +8,16 @@ local util = require("scada-common.util")
 
 local databus = {}
 
+-- databus PSIL
+databus.ps = psil.create()
+
 local dbus_iface = {
-    ps = psil.create(),
     rps_scram = function () log.debug("DBUS: unset rps_scram() called") end,
     rps_reset = function () log.debug("DBUS: unset rps_reset() called") end
 }
 
 -- call to toggle heartbeat signal
-function databus.heartbeat() dbus_iface.ps.toggle("heartbeat") end
+function databus.heartbeat() databus.ps.toggle("heartbeat") end
 
 -- link RPS command functions
 ---@param scram function reactor SCRAM function
@@ -35,42 +37,42 @@ function databus.rps_reset() dbus_iface.rps_reset() end
 ---@param plc_v string PLC version
 ---@param comms_v string comms version
 function databus.tx_versions(plc_v, comms_v)
-    dbus_iface.ps.publish("version", plc_v)
-    dbus_iface.ps.publish("comms_version", comms_v)
+    databus.ps.publish("version", plc_v)
+    databus.ps.publish("comms_version", comms_v)
 end
 
 -- transmit unit ID across the bus
 ---@param id integer unit ID
 function databus.tx_id(id)
-    dbus_iface.ps.publish("unit_id", id)
+    databus.ps.publish("unit_id", id)
 end
 
 -- transmit hardware status across the bus
 ---@param plc_state plc_state
 function databus.tx_hw_status(plc_state)
-    dbus_iface.ps.publish("reactor_dev_state", util.trinary(plc_state.no_reactor, 1, util.trinary(plc_state.reactor_formed, 3, 2)))
-    dbus_iface.ps.publish("has_modem", not plc_state.no_modem)
-    dbus_iface.ps.publish("degraded", plc_state.degraded)
-    dbus_iface.ps.publish("init_ok", plc_state.init_ok)
+    databus.ps.publish("reactor_dev_state", util.trinary(plc_state.no_reactor, 1, util.trinary(plc_state.reactor_formed, 3, 2)))
+    databus.ps.publish("has_modem", not plc_state.no_modem)
+    databus.ps.publish("degraded", plc_state.degraded)
+    databus.ps.publish("init_ok", plc_state.init_ok)
 end
 
 -- transmit thread (routine) statuses
 ---@param thread string thread name
 ---@param ok boolean thread state
 function databus.tx_rt_status(thread, ok)
-    dbus_iface.ps.publish(util.c("routine__", thread), ok)
+    databus.ps.publish(util.c("routine__", thread), ok)
 end
 
 -- transmit supervisor link state across the bus
 ---@param state integer
 function databus.tx_link_state(state)
-    dbus_iface.ps.publish("link_state", state)
+    databus.ps.publish("link_state", state)
 end
 
 -- transmit reactor enable state across the bus
 ---@param active boolean reactor active
 function databus.tx_reactor_state(active)
-    dbus_iface.ps.publish("reactor_active", active)
+    databus.ps.publish("reactor_active", active)
 end
 
 -- transmit RPS data across the bus
@@ -78,26 +80,26 @@ end
 ---@param status table RPS status
 ---@param emer_cool_active boolean RPS activated the emergency coolant
 function databus.tx_rps(tripped, status, emer_cool_active)
-    dbus_iface.ps.publish("rps_scram", tripped)
-    dbus_iface.ps.publish("rps_damage", status[1])
-    dbus_iface.ps.publish("rps_high_temp", status[2])
-    dbus_iface.ps.publish("rps_low_ccool", status[3])
-    dbus_iface.ps.publish("rps_high_waste", status[4])
-    dbus_iface.ps.publish("rps_high_hcool", status[5])
-    dbus_iface.ps.publish("rps_no_fuel", status[6])
-    dbus_iface.ps.publish("rps_fault", status[7])
-    dbus_iface.ps.publish("rps_timeout", status[8])
-    dbus_iface.ps.publish("rps_manual", status[9])
-    dbus_iface.ps.publish("rps_automatic", status[10])
-    dbus_iface.ps.publish("rps_sysfail", status[11])
-    dbus_iface.ps.publish("emer_cool", emer_cool_active)
+    databus.ps.publish("rps_scram", tripped)
+    databus.ps.publish("rps_damage", status[1])
+    databus.ps.publish("rps_high_temp", status[2])
+    databus.ps.publish("rps_low_ccool", status[3])
+    databus.ps.publish("rps_high_waste", status[4])
+    databus.ps.publish("rps_high_hcool", status[5])
+    databus.ps.publish("rps_no_fuel", status[6])
+    databus.ps.publish("rps_fault", status[7])
+    databus.ps.publish("rps_timeout", status[8])
+    databus.ps.publish("rps_manual", status[9])
+    databus.ps.publish("rps_automatic", status[10])
+    databus.ps.publish("rps_sysfail", status[11])
+    databus.ps.publish("emer_cool", emer_cool_active)
 end
 
 -- link a function to receive data from the bus
 ---@param field string field name
 ---@param func function function to link
 function databus.rx_field(field, func)
-    dbus_iface.ps.subscribe(field, func)
+    databus.ps.subscribe(field, func)
 end
 
 return databus
diff --git a/reactor-plc/panel/front_panel.lua b/reactor-plc/panel/front_panel.lua
index c000a3d..8e28a75 100644
--- a/reactor-plc/panel/front_panel.lua
+++ b/reactor-plc/panel/front_panel.lua
@@ -31,7 +31,7 @@ local border = core.border
 ---@param panel graphics_element main displaybox
 local function init(panel)
     local header = TextBox{parent=panel,y=1,text="REACTOR PLC - UNIT ?",alignment=TEXT_ALIGN.CENTER,height=1,fg_bg=style.header}
-    databus.rx_field("unit_id", function (id) header.set_value(util.c("REACTOR PLC - UNIT ", id)) end)
+    header.register(databus.ps, "unit_id", function (id) header.set_value(util.c("REACTOR PLC - UNIT ", id)) end)
 
     --
     -- system indicators
@@ -43,8 +43,8 @@ local function init(panel)
     local heartbeat = LED{parent=system,label="HEARTBEAT",colors=cpair(colors.green,colors.green_off)}
     system.line_break()
 
-    databus.rx_field("init_ok", init_ok.update)
-    databus.rx_field("heartbeat", heartbeat.update)
+    init_ok.register(databus.ps, "init_ok", init_ok.update)
+    heartbeat.register(databus.ps, "heartbeat", heartbeat.update)
 
     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)}
@@ -52,9 +52,9 @@ local function init(panel)
     network.update(5)
     system.line_break()
 
-    databus.rx_field("reactor_dev_state", reactor.update)
-    databus.rx_field("has_modem", modem.update)
-    databus.rx_field("link_state", network.update)
+    reactor.register(databus.ps, "reactor_dev_state", reactor.update)
+    modem.register(databus.ps, "has_modem", modem.update)
+    network.register(databus.ps, "link_state", network.update)
 
     local rt_main = LED{parent=system,label="RT MAIN",colors=cpair(colors.green,colors.green_off)}
     local rt_rps  = LED{parent=system,label="RT RPS",colors=cpair(colors.green,colors.green_off)}
@@ -63,11 +63,11 @@ local function init(panel)
     local rt_sctl = LED{parent=system,label="RT SPCTL",colors=cpair(colors.green,colors.green_off)}
     system.line_break()
 
-    databus.rx_field("routine__main", rt_main.update)
-    databus.rx_field("routine__rps", rt_rps.update)
-    databus.rx_field("routine__comms_tx", rt_cmtx.update)
-    databus.rx_field("routine__comms_rx", rt_cmrx.update)
-    databus.rx_field("routine__spctl", rt_sctl.update)
+    rt_main.register(databus.ps, "routine__main", rt_main.update)
+    rt_rps.register(databus.ps, "routine__rps", rt_rps.update)
+    rt_cmtx.register(databus.ps, "routine__comms_tx", rt_cmtx.update)
+    rt_cmrx.register(databus.ps, "routine__comms_rx", rt_cmrx.update)
+    rt_sctl.register(databus.ps, "routine__spctl", rt_sctl.update)
 
     --
     -- status & controls
@@ -80,7 +80,7 @@ local function init(panel)
     -- only show emergency coolant LED if emergency coolant is configured for this device
     if type(config.EMERGENCY_COOL) == "table" then
         local emer_cool = LED{parent=status,x=2,width=14,label="EMER COOLANT",colors=cpair(colors.yellow,colors.yellow_off)}
-        databus.rx_field("emer_cool", emer_cool.update)
+        emer_cool.register(databus.ps, "emer_cool", emer_cool.update)
     end
 
     local status_trip_rct = Rectangle{parent=status,width=20,height=3,x=1,border=border(1,colors.lightGray,true),even_inner=true,fg_bg=cpair(colors.black,colors.ivory)}
@@ -92,8 +92,8 @@ local function init(panel)
     PushButton{parent=controls,x=1,y=1,min_width=7,text="SCRAM",callback=databus.rps_scram,fg_bg=cpair(colors.black,colors.red),active_fg_bg=cpair(colors.black,colors.red_off)}
     PushButton{parent=controls,x=9,y=1,min_width=7,text="RESET",callback=databus.rps_reset,fg_bg=cpair(colors.black,colors.yellow),active_fg_bg=cpair(colors.black,colors.yellow_off)}
 
-    databus.rx_field("reactor_active", active.update)
-    databus.rx_field("rps_scram", scram.update)
+    active.register(databus.ps, "reactor_active", active.update)
+    scram.register(databus.ps, "rps_scram", scram.update)
 
     --
     -- about footer
@@ -103,8 +103,8 @@ local function init(panel)
     local fw_v    = TextBox{parent=about,x=2,y=1,text="FW: v00.00.00",alignment=TEXT_ALIGN.LEFT,height=1}
     local comms_v = TextBox{parent=about,x=17,y=1,text="NT: v00.00.00",alignment=TEXT_ALIGN.LEFT,height=1}
 
-    databus.rx_field("version", function (version) fw_v.set_value(util.c("FW: ", version)) end)
-    databus.rx_field("comms_version", function (version) comms_v.set_value(util.c("NT: v", version)) end)
+    fw_v.register(databus.ps, "version", function (version) fw_v.set_value(util.c("FW: ", version)) end)
+    comms_v.register(databus.ps, "comms_version", function (version) comms_v.set_value(util.c("NT: v", version)) end)
 
     --
     -- rps list
@@ -126,17 +126,17 @@ local function init(panel)
     local rps_ccl  = LED{parent=rps,label="LO CCOOLANT",colors=cpair(colors.red,colors.red_off)}
     local rps_hcl  = LED{parent=rps,label="HI HCOOLANT",colors=cpair(colors.red,colors.red_off)}
 
-    databus.rx_field("rps_manual", rps_man.update)
-    databus.rx_field("rps_automatic", rps_auto.update)
-    databus.rx_field("rps_timeout", rps_tmo.update)
-    databus.rx_field("rps_fault", rps_flt.update)
-    databus.rx_field("rps_sysfail", rps_fail.update)
-    databus.rx_field("rps_damage", rps_dmg.update)
-    databus.rx_field("rps_high_temp", rps_tmp.update)
-    databus.rx_field("rps_no_fuel", rps_nof.update)
-    databus.rx_field("rps_high_waste", rps_wst.update)
-    databus.rx_field("rps_low_ccool", rps_ccl.update)
-    databus.rx_field("rps_high_hcool", rps_hcl.update)
+    rps_man.register(databus.ps, "rps_manual", rps_man.update)
+    rps_auto.register(databus.ps, "rps_automatic", rps_auto.update)
+    rps_tmo.register(databus.ps, "rps_timeout", rps_tmo.update)
+    rps_flt.register(databus.ps, "rps_fault", rps_flt.update)
+    rps_fail.register(databus.ps, "rps_sysfail", rps_fail.update)
+    rps_dmg.register(databus.ps, "rps_damage", rps_dmg.update)
+    rps_tmp.register(databus.ps, "rps_high_temp", rps_tmp.update)
+    rps_nof.register(databus.ps, "rps_no_fuel", rps_nof.update)
+    rps_wst.register(databus.ps, "rps_high_waste", rps_wst.update)
+    rps_ccl.register(databus.ps, "rps_low_ccool", rps_ccl.update)
+    rps_hcl.register(databus.ps, "rps_high_hcool", rps_hcl.update)
 end
 
 return init
diff --git a/reactor-plc/renderer.lua b/reactor-plc/renderer.lua
index 9830751..038918b 100644
--- a/reactor-plc/renderer.lua
+++ b/reactor-plc/renderer.lua
@@ -44,10 +44,8 @@ function renderer.close_ui()
         -- stop blinking indicators
         flasher.clear()
 
-        -- hide to stop animation callbacks
-        ui.display.hide()
-
-        -- clear root UI elements
+        -- delete element tree
+        ui.display.delete()
         ui.display = nil
 
         -- restore colors
diff --git a/reactor-plc/startup.lua b/reactor-plc/startup.lua
index 183fbf3..540b1fd 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 = "v1.2.0"
+local R_PLC_VERSION = "v1.3.0"
 
 local println = util.println
 local println_ts = util.println_ts