diff --git a/reactor-plc/config/system.lua b/reactor-plc/config/system.lua
index 909dda7..594a7e5 100644
--- a/reactor-plc/config/system.lua
+++ b/reactor-plc/config/system.lua
@@ -82,8 +82,9 @@ function system.create(tool_ctl, main_pane, cfg_sys, divs, style, exit)
     local plc_c_2 = Div{parent=plc_cfg,x=2,y=4,width=49}
     local plc_c_3 = Div{parent=plc_cfg,x=2,y=4,width=49}
     local plc_c_4 = Div{parent=plc_cfg,x=2,y=4,width=49}
+    local plc_c_5 = Div{parent=plc_cfg,x=2,y=4,width=49}
 
-    local plc_pane = MultiPane{parent=plc_cfg,x=1,y=4,panes={plc_c_1,plc_c_2,plc_c_3,plc_c_4}}
+    local plc_pane = MultiPane{parent=plc_cfg,x=1,y=4,panes={plc_c_1,plc_c_2,plc_c_3,plc_c_4,plc_c_5}}
 
     TextBox{parent=plc_cfg,x=1,y=2,text=" PLC Configuration",fg_bg=cpair(colors.black,colors.orange)}
 
@@ -152,13 +153,20 @@ function system.create(tool_ctl, main_pane, cfg_sys, divs, style, exit)
 
     function self.bundled_emcool(en) if en then color.enable() else color.disable() end end
 
+    TextBox{parent=plc_c_5,x=1,y=1,height=5,text="Advanced Options"}
+    local invert = Checkbox{parent=plc_c_5,x=1,y=3,label="Invert",default=ini_cfg.EmerCoolInvert,box_fg_bg=cpair(colors.orange,colors.black),callback=function()end}
+    TextBox{parent=plc_c_5,x=3,y=4,height=4,text="Digital I/O is already inverted (or not) based on intended use. If you have a non-standard setup, you can use this option to avoid needing a redstone inverter.",fg_bg=cpair(colors.gray,colors.lightGray)}
+    PushButton{parent=plc_c_5,x=1,y=14,text="\x1b Back",callback=function()plc_pane.set_value(4)end,fg_bg=nav_fg_bg,active_fg_bg=btn_act_fg_bg}
+
     local function submit_emcool()
         tmp_cfg.EmerCoolSide = side_options_map[side.get_value()]
         tmp_cfg.EmerCoolColor = util.trinary(bundled.get_value(), color_options_map[color.get_value()], nil)
+        tmp_cfg.EmerCoolInvert = invert.get_value()
         next_from_plc()
     end
 
     PushButton{parent=plc_c_4,x=1,y=14,text="\x1b Back",callback=function()plc_pane.set_value(3)end,fg_bg=nav_fg_bg,active_fg_bg=btn_act_fg_bg}
+    PushButton{parent=plc_c_4,x=33,y=14,min_width=10,text="Advanced",callback=function()plc_pane.set_value(5)end,fg_bg=cpair(colors.black,colors.yellow),active_fg_bg=btn_act_fg_bg,dis_fg_bg=btn_dis_fg_bg}
     PushButton{parent=plc_c_4,x=44,y=14,text="Next \x1a",callback=submit_emcool,fg_bg=nav_fg_bg,active_fg_bg=btn_act_fg_bg}
 
     --#endregion
@@ -461,6 +469,7 @@ function system.create(tool_ctl, main_pane, cfg_sys, divs, style, exit)
             try_set(side, side_to_idx(ini_cfg.EmerCoolSide))
             try_set(bundled, ini_cfg.EmerCoolColor ~= nil)
             if ini_cfg.EmerCoolColor ~= nil then try_set(color, color_to_idx(ini_cfg.EmerCoolColor)) end
+            try_set(invert, ini_cfg.EmerCoolInvert)
             try_set(svr_chan, ini_cfg.SVR_Channel)
             try_set(plc_chan, ini_cfg.PLC_Channel)
             try_set(timeout, ini_cfg.ConnTimeout)
@@ -533,9 +542,11 @@ function system.create(tool_ctl, main_pane, cfg_sys, divs, style, exit)
         if tmp_cfg.EmerCoolEnable then
             tmp_cfg.EmerCoolSide = config.EMERGENCY_COOL.side
             tmp_cfg.EmerCoolColor = config.EMERGENCY_COOL.color
+            tmp_cfg.EmerCoolInvert = false
         else
             tmp_cfg.EmerCoolSide = nil
             tmp_cfg.EmerCoolColor = nil
+            tmp_cfg.EmerCoolInvert = false
         end
 
         tmp_cfg.SVR_Channel = config.SVR_CHANNEL
diff --git a/reactor-plc/configure.lua b/reactor-plc/configure.lua
index b2baa6d..fbc25c1 100644
--- a/reactor-plc/configure.lua
+++ b/reactor-plc/configure.lua
@@ -32,7 +32,8 @@ local changes = {
     { "v1.6.2", { "AuthKey minimum length is now 8 (if set)" } },
     { "v1.6.8", { "ConnTimeout can now have a fractional part" } },
     { "v1.6.15", { "Added front panel UI theme", "Added color accessibility modes" } },
-    { "v1.7.3", { "Added standard with black off state color mode", "Added blue indicator color modes" } }
+    { "v1.7.3", { "Added standard with black off state color mode", "Added blue indicator color modes" } },
+    { "v1.8.21", { "Added option to invert emergency coolant redstone control" } }
 }
 
 ---@class plc_configurator
@@ -76,6 +77,7 @@ local tmp_cfg = {
     EmerCoolEnable = false,
     EmerCoolSide = nil,     ---@type string|nil
     EmerCoolColor = nil,    ---@type color|nil
+    EmerCoolInvert = false, ---@type boolean
     SVR_Channel = nil,      ---@type integer
     PLC_Channel = nil,      ---@type integer
     ConnTimeout = nil,      ---@type number
@@ -100,6 +102,7 @@ local fields = {
     { "EmerCoolEnable", "Emergency Coolant", false },
     { "EmerCoolSide", "Emergency Coolant Side", nil },
     { "EmerCoolColor", "Emergency Coolant Color", nil },
+    { "EmerCoolInvert", "Emergency Coolant Invert", false },
     { "SVR_Channel", "SVR Channel", 16240 },
     { "PLC_Channel", "PLC Channel", 16241 },
     { "ConnTimeout", "Connection Timeout", 5 },
diff --git a/reactor-plc/plc.lua b/reactor-plc/plc.lua
index 73b95ce..a2929cb 100644
--- a/reactor-plc/plc.lua
+++ b/reactor-plc/plc.lua
@@ -43,6 +43,7 @@ function plc.load_config()
     config.EmerCoolEnable = settings.get("EmerCoolEnable")
     config.EmerCoolSide = settings.get("EmerCoolSide")
     config.EmerCoolColor = settings.get("EmerCoolColor")
+    config.EmerCoolInvert = settings.get("EmerCoolInvert")
 
     config.SVR_Channel = settings.get("SVR_Channel")
     config.PLC_Channel = settings.get("PLC_Channel")
@@ -98,6 +99,7 @@ function plc.validate_config(cfg)
     if cfg.EmerCoolEnable then
         cfv.assert_eq(rsio.is_valid_side(cfg.EmerCoolSide), true)
         cfv.assert_eq(cfg.EmerCoolColor == nil or rsio.is_color(cfg.EmerCoolColor), true)
+        cfv.assert_type_bool(cfg.EmerCoolInvert)
     end
 
     return cfv.valid()
@@ -166,7 +168,8 @@ function plc.rps_init(reactor, is_formed)
     local function _set_emer_cool(state)
         -- check if this was configured: if it's a table, fields have already been validated.
         if config.EmerCoolEnable then
-            local level = rsio.digital_write_active(rsio.IO.U_EMER_COOL, state)
+            -- use ~= as XOR for simple inversion
+            local level = rsio.digital_write_active(rsio.IO.U_EMER_COOL, config.EmerCoolInvert ~= state)
 
             if level ~= false then
                 if rsio.is_color(config.EmerCoolColor) then
diff --git a/reactor-plc/startup.lua b/reactor-plc/startup.lua
index c085e95..af54333 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 = "v1.8.20"
+local R_PLC_VERSION = "v1.8.21"
 
 local println = util.println
 local println_ts = util.println_ts