diff --git a/scada-common/rsio.lua b/scada-common/rsio.lua
index ebc91f4..468a1fa 100644
--- a/scada-common/rsio.lua
+++ b/scada-common/rsio.lua
@@ -1,37 +1,115 @@
+IO_LVL = {
+    LOW = 0,
+    HIGH = 1
+}
+
 RS_IO = {
     -- digital inputs --
 
     -- facility
-    F_SCRAM,    -- active high, facility-wide scram
-    F_AE2_LIVE, -- active high, indicates whether AE2 network is online (hint: use redstone P2P)
+    F_SCRAM       = 1,  -- active low, facility-wide scram
+    F_AE2_LIVE    = 2,  -- active high, indicates whether AE2 network is online (hint: use redstone P2P)
 
     -- reactor
-    R_SCRAM,    -- active high, reactor scram
-    R_ENABLE,   -- active high, reactor enable
+    R_SCRAM       = 3,  -- active low, reactor scram
+    R_ENABLE      = 4,  -- active high, reactor enable
 
     -- digital outputs --
 
     -- waste
-    WASTE_PO,   -- active low, polonium routing
-    WASTE_PU,   -- active low, plutonium routing
-    WASTE_AM,   -- active low, antimatter routing
+    WASTE_PO      = 5,  -- active low, polonium routing
+    WASTE_PU      = 6,  -- active low, plutonium routing
+    WASTE_AM      = 7,  -- active low, antimatter routing
 
     -- reactor
-    R_SCRAMMED,     -- if the reactor is scrammed
-    R_AUTO_SCRAM,   -- if the reactor was automatically scrammed
-    R_ACTIVE,       -- if the reactor is active
-    R_AUTO_CTRL,    -- if the reactor burn rate is automatic
-    R_DMG_CRIT,     -- if the reactor damage is critical
-    R_HIGH_TEMP,    -- if the reactor is at a high temperature
-    R_NO_COOLANT,   -- if the reactor has no coolant
-    R_EXCESS_HC,    -- if the reactor has excess heated coolant
-    R_EXCESS_WS,    -- if the reactor has excess waste
-    R_INSUFF_FUEL,  -- if the reactor has insufficent fuel
-    R_PLC_TIMEOUT,  -- if the reactor PLC has not been heard from
+    R_SCRAMMED    = 8,  -- active high, if the reactor is scrammed
+    R_AUTO_SCRAM  = 9,  -- active high, if the reactor was automatically scrammed
+    R_ACTIVE      = 10, -- active high, if the reactor is active
+    R_AUTO_CTRL   = 11, -- active high, if the reactor burn rate is automatic
+    R_DMG_CRIT    = 12, -- active high, if the reactor damage is critical
+    R_HIGH_TEMP   = 13, -- active high, if the reactor is at a high temperature
+    R_NO_COOLANT  = 14, -- active high, if the reactor has no coolant
+    R_EXCESS_HC   = 15, -- active high, if the reactor has excess heated coolant
+    R_EXCESS_WS   = 16, -- active high, if the reactor has excess waste
+    R_INSUFF_FUEL = 17, -- active high, if the reactor has insufficent fuel
+    R_PLC_TIMEOUT = 18, -- active high, if the reactor PLC has not been heard from
 
     -- analog outputs --
 
-    A_R_BURN_RATE,  -- reactor burn rate percentage
-    A_B_BOIL_RATE,  -- boiler boil rate percentage
-    A_T_FLOW_RATE   -- turbine flow rate percentage
+    A_R_BURN_RATE = 19, -- reactor burn rate percentage
+    A_B_BOIL_RATE = 20, -- boiler boil rate percentage
+    A_T_FLOW_RATE = 21  -- turbine flow rate percentage
 }
+
+local _TRINARY = function (cond, t, f) if cond then return t else return f end end
+
+local _DI_ACTIVE_HIGH = function (level) return level == IO_LVL.HIGH end
+local _DI_ACTIVE_LOW = function (level) return level == IO_LVL.LOW end
+local _DO_ACTIVE_HIGH = function (on) return _TRINARY(on, IO_LVL.HIGH, IO_LVL.LOW) end
+local _DO_ACTIVE_LOW = function (on) return _TRINARY(on, IO_LVL.LOW, IO_LVL.HIGH) end
+
+local RS_DIO_MAP = {
+    -- F_SCRAM
+    _DI_ACTIVE_LOW,
+    -- F_AE2_LIVE
+    _DI_ACTIVE_HIGH,
+    -- R_SCRAM
+    _DI_ACTIVE_LOW,
+    -- R_ENABLE
+    _DI_ACTIVE_HIGH,
+    -- WASTE_PO
+    _DO_ACTIVE_LOW,
+    -- WASTE_PU
+    _DO_ACTIVE_LOW,
+    -- WASTE_AM
+    _DO_ACTIVE_LOW,
+    -- R_SCRAMMED
+    _DO_ACTIVE_HIGH,
+    -- R_AUTO_SCRAM
+    _DO_ACTIVE_HIGH,
+    -- R_ACTIVE
+    _DO_ACTIVE_HIGH,
+    -- R_AUTO_CTRL
+    _DO_ACTIVE_HIGH,
+    -- R_DMG_CRIT
+    _DO_ACTIVE_HIGH,
+    -- R_HIGH_TEMP
+    _DO_ACTIVE_HIGH,
+    -- R_NO_COOLANT
+    _DO_ACTIVE_HIGH,
+    -- R_EXCESS_HC
+    _DO_ACTIVE_HIGH,
+    -- R_EXCESS_WS
+    _DO_ACTIVE_HIGH,
+    -- R_INSUFF_FUEL
+    _DO_ACTIVE_HIGH,
+    -- R_PLC_TIMEOUT
+    _DO_ACTIVE_HIGH
+}
+
+-- get digital IO level reading
+function digital_input_read(rs_value)
+    if rs_value then
+        return IO_LVL.HIGH
+    else
+        return IO_LVL.LOW
+    end
+end
+
+-- returns true if the level corresponds to active
+function digital_input_is_active(channel, level)
+    if channel > RS_IO.R_ENABLE then
+        return false
+    else
+        return RS_DIO_MAP[channel](level)
+    end
+end
+
+-- returns the level corresponding to active
+function digital_output_write(channel, active)
+    if channel < RS_IO.WASTE_PO or channel > RS_IO.R_PLC_TIMEOUT then
+        return IO_LVL.LOW
+    else
+        return RS_DIO_MAP[channel](level)
+    end
+end