#159 linked up redstone I/O

rtu/startup.lua

@@ -25,7 +25,7 @@ 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 = "beta-v0.10.6"
+local RTU_VERSION = "beta-v0.11.0"
 
 local rtu_t = types.rtu_t
 

scada-common/rsio.lua

@@ -11,7 +11,7 @@ local rsio = {}
 -- RS I/O CONSTANTS --
 ----------------------
 
----@alias IO_LVL integer
+---@enum IO_LVL I/O logic level
 local IO_LVL = {
     DISCONNECT = -1, -- use for RTU session to indicate this RTU is not connected to this port
     LOW = 0,
@@ -19,13 +19,13 @@ local IO_LVL = {
     FLOATING = 2     -- use for RTU session to indicate this RTU is connected but not yet read
 }
 
----@alias IO_DIR integer
+---@enum IO_DIR I/O direction
 local IO_DIR = {
     IN = 0,
     OUT = 1
 }
 
----@alias IO_MODE integer
+---@enum IO_MODE I/O mode (digital/analog input/output)
 local IO_MODE = {
     DIGITAL_IN = 0,
     DIGITAL_OUT = 1,
@@ -33,45 +33,50 @@ local IO_MODE = {
     ANALOG_OUT = 3
 }
 
----@alias IO_PORT integer
+---@enum IO_PORT redstone I/O logic port
 local IO_PORT = {
     -- digital inputs --
 
     -- facility
     F_SCRAM       = 1,  -- active low, facility-wide scram
+    F_ACK         = 2,  -- active high, facility alarm acknowledge
 
     -- reactor
-    R_SCRAM       = 2,  -- active low, reactor scram
+    R_SCRAM       = 3,  -- active low, reactor scram
-    R_ENABLE      = 3,  -- active high, reactor enable
+    R_RESET       = 4,  -- active high, reactor RPS reset
+    R_ENABLE      = 5,  -- active high, reactor enable
+
+    -- unit
+    U_ACK         = 6,  -- active high, unit alarm acknowledge
 
     -- digital outputs --
 
     -- facility
-    F_ALARM       = 4,  -- active high, facility safety alarm
+    F_ALARM       = 7,  -- active high, facility alarm (any high priority unit alarm)
 
     -- waste
-    WASTE_PU      = 5,  -- active low, waste -> plutonium -> pellets route
+    WASTE_PU      = 8,  -- active low, waste -> plutonium -> pellets route
-    WASTE_PO      = 6,  -- active low, waste -> polonium route
+    WASTE_PO      = 9,  -- active low, waste -> polonium route
-    WASTE_POPL    = 7,  -- active low, polonium -> pellets route
+    WASTE_POPL    = 10, -- active low, polonium -> pellets route
-    WASTE_AM      = 8,  -- active low, polonium -> anti-matter route
+    WASTE_AM      = 11, -- active low, polonium -> anti-matter route
 
     -- reactor
-    R_ALARM       = 9,  -- active high, reactor safety alarm
-    R_SCRAMMED    = 10, -- active high, if the reactor is scrammed
-    R_AUTO_SCRAM  = 11, -- active high, if the reactor was automatically scrammed
     R_ACTIVE      = 12, -- active high, if the reactor is active
     R_AUTO_CTRL   = 13, -- active high, if the reactor burn rate is automatic
-    R_DMG_CRIT    = 14, -- active high, if the reactor damage is critical
+    R_SCRAMMED    = 14, -- active high, if the reactor is scrammed
-    R_HIGH_TEMP   = 15, -- active high, if the reactor is at a high temperature
+    R_AUTO_SCRAM  = 15, -- active high, if the reactor was automatically scrammed
-    R_NO_COOLANT  = 16, -- active high, if the reactor has no coolant
+    R_DMG_CRIT    = 16, -- active high, if the reactor damage is critical
-    R_EXCESS_HC   = 17, -- active high, if the reactor has excess heated coolant
+    R_HIGH_TEMP   = 17, -- active high, if the reactor is at a high temperature
-    R_EXCESS_WS   = 18, -- active high, if the reactor has excess waste
+    R_NO_COOLANT  = 18, -- active high, if the reactor has no coolant
-    R_INSUFF_FUEL = 19, -- active high, if the reactor has insufficent fuel
+    R_EXCESS_HC   = 19, -- active high, if the reactor has excess heated coolant
-    R_PLC_FAULT   = 20, -- active high, if the reactor PLC reports a device access fault
+    R_EXCESS_WS   = 20, -- active high, if the reactor has excess waste
-    R_PLC_TIMEOUT = 21, -- active high, if the reactor PLC has not been heard from
+    R_INSUFF_FUEL = 21, -- active high, if the reactor has insufficent fuel
+    R_PLC_FAULT   = 22, -- active high, if the reactor PLC reports a device access fault
+    R_PLC_TIMEOUT = 23, -- active high, if the reactor PLC has not been heard from
 
     -- unit outputs
-    U_EMER_COOL   = 22  -- active low, emergency coolant control
+    U_ALARM       = 24,  -- active high, unit alarm
+    U_EMER_COOL   = 25  -- active low, emergency coolant control
 }
 
 rsio.IO_LVL = IO_LVL
@@ -88,18 +93,20 @@ rsio.IO = IO_PORT
 function rsio.to_string(port)
     local names = {
         "F_SCRAM",
+        "F_ACK",
         "R_SCRAM",
+        "R_RESET",
         "R_ENABLE",
+        "U_ACK",
         "F_ALARM",
         "WASTE_PU",
         "WASTE_PO",
         "WASTE_POPL",
         "WASTE_AM",
-        "R_ALARM",
-        "R_SCRAMMED",
-        "R_AUTO_SCRAM",
         "R_ACTIVE",
         "R_AUTO_CTRL",
+        "R_SCRAMMED",
+        "R_AUTO_SCRAM",
         "R_DMG_CRIT",
         "R_HIGH_TEMP",
         "R_NO_COOLANT",
@@ -108,6 +115,7 @@ function rsio.to_string(port)
         "R_INSUFF_FUEL",
         "R_PLC_FAULT",
         "R_PLC_TIMEOUT",
+        "U_ALARM",
         "U_EMER_COOL"
     }
 
@@ -129,12 +137,22 @@ local function _O_ACTIVE_LOW(active) if active then return IO_LVL.LOW else retur
 local RS_DIO_MAP = {
     -- F_SCRAM
     { _in = _I_ACTIVE_LOW,  _out = _O_ACTIVE_LOW,  mode = IO_DIR.IN  },
+    -- F_ACK
+    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.IN  },
+
     -- R_SCRAM
     { _in = _I_ACTIVE_LOW,  _out = _O_ACTIVE_LOW,  mode = IO_DIR.IN  },
+    -- R_RESET
+    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.IN  },
     -- R_ENABLE
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.IN  },
+
+    -- U_ACK
+    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.IN  },
+
     -- F_ALARM
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
+
     -- WASTE_PU
     { _in = _I_ACTIVE_LOW,  _out = _O_ACTIVE_LOW,  mode = IO_DIR.OUT },
     -- WASTE_PO
@@ -143,16 +161,15 @@ local RS_DIO_MAP = {
     { _in = _I_ACTIVE_LOW,  _out = _O_ACTIVE_LOW,  mode = IO_DIR.OUT },
     -- WASTE_AM
     { _in = _I_ACTIVE_LOW,  _out = _O_ACTIVE_LOW,  mode = IO_DIR.OUT },
-    -- R_ALARM
+
+    -- R_ACTIVE
+    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
+    -- R_AUTO_CTRL
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
     -- R_SCRAMMED
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
     -- R_AUTO_SCRAM
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
-    -- R_ACTIVE
-    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
-    -- R_AUTO_CTRL
-    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
     -- R_DMG_CRIT
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
     -- R_HIGH_TEMP
@@ -169,6 +186,9 @@ local RS_DIO_MAP = {
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
     -- R_PLC_TIMEOUT
     { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
+
+    -- U_ALARM
+    { _in = _I_ACTIVE_HIGH, _out = _O_ACTIVE_HIGH, mode = IO_DIR.OUT },
     -- U_EMER_COOL
     { _in = _I_ACTIVE_LOW,  _out = _O_ACTIVE_LOW,  mode = IO_DIR.OUT }
 }
@@ -179,18 +199,20 @@ local RS_DIO_MAP = {
 function rsio.get_io_mode(port)
     local modes = {
         IO_MODE.DIGITAL_IN,     -- F_SCRAM
+        IO_MODE.DIGITAL_IN,     -- F_ACK
         IO_MODE.DIGITAL_IN,     -- R_SCRAM
+        IO_MODE.DIGITAL_IN,     -- R_RESET
         IO_MODE.DIGITAL_IN,     -- R_ENABLE
+        IO_MODE.DIGITAL_IN,     -- U_ACK
         IO_MODE.DIGITAL_OUT,    -- F_ALARM
         IO_MODE.DIGITAL_OUT,    -- WASTE_PU
         IO_MODE.DIGITAL_OUT,    -- WASTE_PO
         IO_MODE.DIGITAL_OUT,    -- WASTE_POPL
         IO_MODE.DIGITAL_OUT,    -- WASTE_AM
-        IO_MODE.DIGITAL_OUT,    -- R_ALARM
-        IO_MODE.DIGITAL_OUT,    -- R_SCRAMMED
-        IO_MODE.DIGITAL_OUT,    -- R_AUTO_SCRAM
         IO_MODE.DIGITAL_OUT,    -- R_ACTIVE
         IO_MODE.DIGITAL_OUT,    -- R_AUTO_CTRL
+        IO_MODE.DIGITAL_OUT,    -- R_SCRAMMED
+        IO_MODE.DIGITAL_OUT,    -- R_AUTO_SCRAM
         IO_MODE.DIGITAL_OUT,    -- R_DMG_CRIT
         IO_MODE.DIGITAL_OUT,    -- R_HIGH_TEMP
         IO_MODE.DIGITAL_OUT,    -- R_NO_COOLANT
@@ -199,6 +221,7 @@ function rsio.get_io_mode(port)
         IO_MODE.DIGITAL_OUT,    -- R_INSUFF_FUEL
         IO_MODE.DIGITAL_OUT,    -- R_PLC_FAULT
         IO_MODE.DIGITAL_OUT,    -- R_PLC_TIMEOUT
+        IO_MODE.DIGITAL_OUT,    -- U_ALARM
         IO_MODE.DIGITAL_OUT     -- U_EMER_COOL
     }
 
@@ -249,11 +272,7 @@ end
 ---@param rs_value boolean
 ---@return IO_LVL
 function rsio.digital_read(rs_value)
-    if rs_value then
+    if rs_value then return IO_LVL.HIGH else return IO_LVL.LOW end
-        return IO_LVL.HIGH
-    else
-        return IO_LVL.LOW
-    end
 end
 
 -- get redstone boolean output value corresponding to a digital I/O level
@@ -280,7 +299,7 @@ end
 ---@param level IO_LVL
 ---@return boolean|nil
 function rsio.digital_is_active(port, level)
-    if (not util.is_int(port)) or (port > IO_PORT.R_ENABLE) then
+    if (not util.is_int(port)) or (port > IO_PORT.U_ACK) then
         return nil
     elseif level == IO_LVL.FLOATING or level == IO_LVL.DISCONNECT then
         return nil
@@ -310,7 +329,7 @@ end
 ---@return number rs_value scaled redstone reading (0 to 15)
 function rsio.analog_write(value, min, max)
     local scaled_value = (value - min) / (max - min)
-    return scaled_value * 15
+    return math.floor(scaled_value * 15)
 end
 
 return rsio

supervisor/facility.lua

@@ -6,11 +6,12 @@ local util  = require("scada-common.util")
 local unit  = require("supervisor.unit")
 
 local rsctl = require("supervisor.session.rsctl")
-local unit  = require("supervisor.session.unit")
 
 local PROCESS = types.PROCESS
 local PROCESS_NAMES = types.PROCESS_NAMES
 
+local IO = rsio.IO
+
 -- 7.14 kJ per blade for 1 mB of fissile fuel<br/>
 -- 2856 FE per blade per 1 mB, 285.6 FE per blade per 0.1 mB (minimum)
 local POWER_PER_BLADE = util.joules_to_fe(7140)
@@ -57,12 +58,15 @@ local facility = {}
 function facility.new(num_reactors, cooling_conf)
     local self = {
         units = {},
+        status_text = { "START UP", "initializing..." },
+        all_sys_ok = false,
+        -- rtus
+        rtu_conn_count = 0,
         redstone = {},
         induction = {},
         envd = {},
-        status_text = { "START UP", "initializing..." },
+        -- redstone I/O control
-        all_sys_ok = false,
+        io_ctl = nil,   ---@type rs_controller
-        rtu_conn_count = 0,
         -- process control
         units_ready = false,
         mode = PROCESS.INACTIVE,
@@ -111,7 +115,7 @@ function facility.new(num_reactors, cooling_conf)
     end
 
     -- init redstone RTU I/O controller
-    local rs_rtu_io_ctl = rsctl.new(self.redstone)
+    self.io_ctl = rsctl.new(self.redstone)
 
     -- unlink disconnected units
     ---@param sessions table
@@ -655,6 +659,36 @@ function facility.new(num_reactors, cooling_conf)
         -- update last mode and set next mode
         self.last_mode = self.mode
         self.mode = next_mode
+
+        -------------------------
+        -- Handle Redstone I/O --
+        -------------------------
+
+        if #self.redstone > 0 then
+            -- handle facility SCRAM
+            if self.io_ctl.digital_read(IO.F_SCRAM) then
+                for i = 1, #self.units do
+                    local u = self.units[i] ---@type reactor_unit
+                    u.cond_scram()
+                end
+            end
+
+            -- handle facility ack
+            if self.io_ctl.digital_read(IO.F_ACK) then public.ack_all() end
+
+            -- update facility alarm output
+            local has_alarm = false
+            for i = 1, #self.units do
+                local u = self.units[i]     ---@type reactor_unit
+
+                if u.has_critical_alarm() then
+                    has_alarm = true
+                    return
+                end
+            end
+
+            self.io_ctl.digital_write(IO.F_ALARM, has_alarm)
+        end
     end
 
     -- call the update function of all units in the facility

supervisor/startup.lua

@@ -14,7 +14,7 @@ local svsessions = require("supervisor.session.svsessions")
 local config     = require("supervisor.config")
 local supervisor = require("supervisor.supervisor")
 
-local SUPERVISOR_VERSION = "beta-v0.11.10"
+local SUPERVISOR_VERSION = "beta-v0.11.11"
 
 local print = util.print
 local println = util.println

supervisor/unit.lua

@@ -74,10 +74,14 @@ function unit.new(for_reactor, num_boilers, num_turbines)
         num_turbines = num_turbines,
         types = { DT_KEYS = DT_KEYS, AISTATE = AISTATE },
         defs = { FLOW_STABILITY_DELAY_MS = FLOW_STABILITY_DELAY_MS },
+        -- rtus
         redstone = {},
         boilers = {},
         turbines = {},
         envd = {},
+        -- redstone control
+        io_ctl = nil,   ---@type rs_controller
+        valves = {},    ---@type unit_valves
         -- auto control
         ramp_target_br100 = 0,
         -- state tracking
@@ -151,7 +155,7 @@ function unit.new(for_reactor, num_boilers, num_turbines)
             -- waste >85%
             ReactorHighWaste     = { state = AISTATE.INACTIVE, trip_time = 0, hold_time = 2, id = ALARM.ReactorHighWaste, tier = PRIO.TIMELY },
             -- RPS trip occured
-            RPSTransient         = { state = AISTATE.INACTIVE, trip_time = 0, hold_time = 1, id = ALARM.RPSTransient, tier = PRIO.URGENT },
+            RPSTransient         = { state = AISTATE.INACTIVE, trip_time = 0, hold_time = 1, id = ALARM.RPSTransient, tier = PRIO.TIMELY },
             -- BoilRateMismatch, CoolantFeedMismatch, SteamFeedMismatch, MaxWaterReturnFeed
             RCSTransient         = { state = AISTATE.INACTIVE, trip_time = 0, hold_time = 5, id = ALARM.RCSTransient, tier = PRIO.TIMELY },
             -- "It's just a routine turbin' trip!" -Bill Gibson, "The China Syndrome"
@@ -223,7 +227,7 @@ function unit.new(for_reactor, num_boilers, num_turbines)
     }
 
     -- init redstone RTU I/O controller
-    local rs_rtu_io_ctl = rsctl.new(self.redstone)
+    self.io_ctl = rsctl.new(self.redstone)
 
     -- init boiler table fields
     for _ = 1, num_boilers do
@@ -272,10 +276,8 @@ function unit.new(for_reactor, num_boilers, num_turbines)
 
     -- get the delta t of a value
     ---@param key string value key
-    ---@return number
+    ---@return number value value or 0 if not known
-    function self._get_dt(key)
+    function self._get_dt(key) if self.deltas[key] then return self.deltas[key].dt else return 0.0 end end
-        if self.deltas[key] then return self.deltas[key].dt else return 0.0 end
-    end
 
     -- update all delta computations
     local function _dt__compute_all()
@@ -320,8 +322,8 @@ function unit.new(for_reactor, num_boilers, num_turbines)
 
     --#region redstone I/O
 
-    local __rs_w = rs_rtu_io_ctl.digital_write
+    local __rs_w = self.io_ctl.digital_write
-    local __rs_r = rs_rtu_io_ctl.digital_read
+    local __rs_r = self.io_ctl.digital_read
 
     -- valves
     local waste_pu  = { open = function () __rs_w(IO.WASTE_PU,    true) end, close = function () __rs_w(IO.WASTE_PU,    false) end }
@@ -330,6 +332,15 @@ function unit.new(for_reactor, num_boilers, num_turbines)
     local waste_sps = { open = function () __rs_w(IO.WASTE_AM,    true) end, close = function () __rs_w(IO.WASTE_AM,    false) end }
     local emer_cool = { open = function () __rs_w(IO.U_EMER_COOL, true) end, close = function () __rs_w(IO.U_EMER_COOL, false) end }
 
+    ---@class unit_valves
+    self.valves = {
+        waste_pu = waste_pu,
+        waste_sna = waste_sna,
+        waste_po = waste_po,
+        waste_sps = waste_sps,
+        emer_cool = emer_cool
+    }
+
     --#endregion
 
     -- unlink disconnected units
@@ -480,13 +491,9 @@ function unit.new(for_reactor, num_boilers, num_turbines)
         -- update status text
         logic.update_status_text(self)
 
-        -- check if emergency coolant is needed
+        -- handle redstone I/O
-        if self.plc_cache.rps_status.no_cool then
+        if #self.redstone > 0 then
-            emer_cool.open()
+            logic.handle_redstone(self)
-        elseif not self.plc_cache.rps_trip then
-            -- can't turn off on sufficient coolant level since it might drop again
-            -- turn off once system is OK again
-            emer_cool.close()
         end
     end
 
@@ -576,6 +583,13 @@ function unit.new(for_reactor, num_boilers, num_turbines)
         end
     end
 
+    -- queue a SCRAM command only if a manual SCRAM has not already occured
+    function public.cond_scram()
+        if self.plc_s ~= nil and not self.plc_cache.rps_status.manual then
+            self.plc_s.in_queue.push_command(PLC_S_CMDS.SCRAM)
+        end
+    end
+
     -- acknowledge all alarms (if possible)
     function public.ack_all()
         for i = 1, #self.db.alarm_states do

supervisor/unitlogic.lua

@@ -3,6 +3,8 @@ local rsio  = require("scada-common.rsio")
 local types = require("scada-common.types")
 local util  = require("scada-common.util")
 
+local plc   = require("supervisor.session.plc")
+
 local ALARM_STATE = types.ALARM_STATE
 
 local TRI_FAIL = types.TRI_FAIL
@@ -10,6 +12,8 @@ local DUMPING_MODE = types.DUMPING_MODE
 
 local IO = rsio.IO
 
+local PLC_S_CMDS = plc.PLC_S_CMDS
+
 local aistate_string = {
     "INACTIVE",
     "TRIPPING",
@@ -620,4 +624,71 @@ function logic.update_status_text(self)
     end
 end
 
+-- handle unit redstone I/O
+---@param self _unit_self unit instance
+function logic.handle_redstone(self)
+    -- reactor controls
+    if self.plc_s ~= nil then
+        if (not self.plc_cache.rps_status.manual) and self.io_ctl.digital_read(IO.R_SCRAM) then
+           -- reactor SCRAM requested but not yet done; perform it
+            self.plc_s.in_queue.push_command(PLC_S_CMDS.SCRAM)
+        end
+
+        if self.plc_cache.rps_trip and self.io_ctl.digital_read(IO.R_RESET) then
+           -- reactor RPS reset requested but not yet done; perform it
+            self.plc_s.in_queue.push_command(PLC_S_CMDS.RPS_RESET)
+        end
+
+        if (not self.db.annunciator.AutoControl) and (not self.plc_cache.active) and
+           (not self.plc_cache.rps_trip) and self.io_ctl.digital_read(IO.R_ACTIVE) then
+           -- reactor enable requested and allowable, but not yet done; perform it
+            self.plc_s.in_queue.push_command(PLC_S_CMDS.ENABLE)
+        end
+    end
+
+    -- check for request to ack all alarms
+    if self.io_ctl.digital_read(IO.U_ACK) then
+        for i = 1, #self.db.alarm_states do
+            if self.db.alarm_states[i] == ALARM_STATE.TRIPPED then
+                self.db.alarm_states[i] = ALARM_STATE.ACKED
+            end
+        end
+    end
+
+    -- write reactor status outputs
+    self.io_ctl.digital_write(IO.R_ACTIVE, self.plc_cache.active)
+    self.io_ctl.digital_write(IO.R_AUTO_CTRL, self.db.annunciator.AutoControl)
+    self.io_ctl.digital_write(IO.R_SCRAMMED, self.plc_cache.rps_trip)
+    self.io_ctl.digital_write(IO.R_AUTO_SCRAM, self.plc_cache.rps_status.automatic)
+    self.io_ctl.digital_write(IO.R_DMG_CRIT, self.plc_cache.rps_status.dmg_crit)
+    self.io_ctl.digital_write(IO.R_HIGH_TEMP, self.plc_cache.rps_status.high_temp)
+    self.io_ctl.digital_write(IO.R_NO_COOLANT, self.plc_cache.rps_status.no_cool)
+    self.io_ctl.digital_write(IO.R_EXCESS_HC, self.plc_cache.rps_status.ex_hcool)
+    self.io_ctl.digital_write(IO.R_EXCESS_WS, self.plc_cache.rps_status.ex_waste)
+    self.io_ctl.digital_write(IO.R_INSUFF_FUEL, self.plc_cache.rps_status.no_fuel)
+    self.io_ctl.digital_write(IO.R_PLC_FAULT, self.plc_cache.rps_status.fault)
+    self.io_ctl.digital_write(IO.R_PLC_TIMEOUT, self.plc_cache.rps_status.timeout)
+
+    -- write unit outputs
+
+    local has_alarm = false
+    for i = 1, #self.db.alarm_states do
+        if self.db.alarm_states[i] == ALARM_STATE.TRIPPED then
+            has_alarm = true
+            break
+        end
+    end
+
+    self.io_ctl.digital_write(IO.U_ALARM, has_alarm)
+
+    -- check if emergency coolant is needed
+    if self.plc_cache.rps_status.no_cool then
+        self.valves.emer_cool.open()
+    elseif not self.plc_cache.rps_trip then
+        -- can't turn off on sufficient coolant level since it might drop again
+        -- turn off once system is OK again
+        self.valves.emer_cool.close()
+    end
+end
+
 return logic