diff --git a/README.md b/README.md
index 203b6e6..bd4d31f 100644
--- a/README.md
+++ b/README.md
@@ -21,8 +21,8 @@ werden ergaenzt, sobald die Peripherie- und Methodennamen der gebauten Anlagen f
 
 ## Einfache Create-Boiler-Anzeige
 
-Fuer die erste Kraftwerksanzeige werden ein Monitor, pro Boiler ein Create-Speedometer,
-ein Create-Stressometer an der Hauptwelle und optional pro Boiler ein Block Reader aus
+Fuer die erste Kraftwerksanzeige werden ein Monitor, ein Create-Speedometer und
+ein Create-Stressometer an der gemeinsamen Hauptwelle sowie pro Boiler ein Block Reader aus
 Advanced Peripherals ueber Wired Modems mit dem Computer verbunden. Installation und Start:
 
 ```lua
@@ -30,11 +30,11 @@ wget https://git.peli-server.de/Dystroyer8/ATM10_CC_Codes/raw/branch/main/create
 create_boiler_display
 ```
 
-Das Programm zeigt pro Boiler Online-Status, RPM und - mit Block Reader - den Heizmodus.
-Zusaetzlich zeigt es Kapazitaet, Verbrauch und Auslastung der Hauptwelle. Die Zuordnung erfolgt
-nach den internen Peripheral-Namen; Speedometer und Block Reader sollten deshalb jeweils in der
-Reihenfolge Boiler 1 bis 3 an das Wired Network angeschlossen werden. Jeder Block Reader muss
-auf den Controller-Tank des zugeordneten Boiler-Multiblocks zeigen.
+Das Programm liest Online-Status und Heizmodus jedes Boilers ueber dessen Block Reader.
+Drehzahl, Kapazitaet, Verbrauch und Auslastung werden fuer die gemeinsame Hauptwelle angezeigt.
+Die Boiler-Zuordnung erfolgt nach den internen Peripheral-Namen; die drei Block Reader sollten
+deshalb in der Reihenfolge Boiler 1 bis 3 an das Wired Network angeschlossen werden. Jeder Block
+Reader muss auf den Controller-Tank des zugeordneten Boiler-Multiblocks zeigen.
 
 ## Struktur
 
diff --git a/create_boiler_display.lua b/create_boiler_display.lua
index 878d95c..d37a633 100644
--- a/create_boiler_display.lua
+++ b/create_boiler_display.lua
@@ -1,9 +1,9 @@
 -- Create boiler status board for CC:Tweaked.
 -- Hardware:
 --   * one monitor
---   * one Create Speedometer per boiler
+--   * one Create Speedometer on the shared main shaft
 --   * one Create Stressometer on the main shaft
---   * optionally one Advanced Peripherals Block Reader per boiler controller
+--   * one Advanced Peripherals Block Reader per boiler controller
 -- Everything must be connected to the computer, preferably using Wired Modems.
 
 local EXPECTED_BOILERS = 3
@@ -76,39 +76,53 @@ local function findBoilerData(data, visited)
   return nil
 end
 
-local function readHeatMode(readerName)
-  if not readerName then return "UNKNOWN" end
+local function readBoiler(readerName)
+  if not readerName then return "MISSING", "UNKNOWN", colors.red end
   local ok, data = pcall(peripheral.call, readerName, "getBlockData")
-  if not ok then return "ERROR" end
+  if not ok then return "ERROR", "UNKNOWN", colors.red end
 
   local boiler = findBoilerData(data)
-  if not boiler then return "UNKNOWN" end
+  if not boiler then return "NO DATA", "UNKNOWN", colors.red end
 
   local passive = getValueIgnoringCase(boiler, { "PassiveHeat", "passive" })
   local heat = tonumber(getValueIgnoringCase(boiler,
-    { "Heat", "activeHeat", "actualHeat", "boilerLevel", "level" }))
+    { "Heat", "activeHeat", "actualHeat" }))
+  local supply = tonumber(getValueIgnoringCase(boiler,
+    { "Supply", "waterSupply", "gatheredSupply" }))
+  local engines = tonumber(getValueIgnoringCase(boiler,
+    { "Engines", "attachedEngines" }))
+  local active = getValueIgnoringCase(boiler,
+    { "Active", "isActive", "prevActive" })
 
-  if passive == true or passive == 1 then return "CAMPFIRE" end
-  if heat and heat >= 18 then return "SUPERHEATED" end
-  if heat and heat > 0 then return "HEATED" end
-  return "COLD"
+  local heatMode
+  if passive == true or passive == 1 then
+    heatMode = "CAMPFIRE"
+  elseif heat and heat >= 18 then
+    heatMode = "SUPERHEATED"
+  elseif heat and heat > 0 then
+    heatMode = "HEATED"
+  else
+    heatMode = "COLD"
+  end
+
+  if active == nil then
+    local hasHeat = heatMode ~= "COLD"
+    local hasWater = supply == nil or supply > 0
+    local hasEngines = engines == nil or engines > 0
+    active = hasHeat and hasWater and hasEngines
+  end
+
+  if active == true or active == 1 then
+    return "ONLINE", heatMode, colors.lime
+  end
+  return "STANDBY", heatMode, colors.orange
 end
 
-local function readBoiler(name, readerName)
-  if not name then
-    return "MISSING", 0, "UNKNOWN", colors.red
-  end
-
-  local ok, speed = pcall(peripheral.call, name, "getSpeed")
-  if not ok or type(speed) ~= "number" then
-    return "ERROR", 0, "UNKNOWN", colors.red
-  end
-
-  speed = math.abs(speed)
-  if speed < 0.5 then
-    return "STANDBY", 0, readHeatMode(readerName), colors.orange
-  end
-  return "ONLINE", speed, readHeatMode(readerName), colors.lime
+local function readMainSpeed(speedometerName)
+  if not speedometerName then return nil end
+  local ok, speed = pcall(peripheral.call, speedometerName, "getSpeed")
+  if not ok or type(speed) ~= "number" then return nil end
+  return math.abs(speed)
 end
 
 local function formatInteger(value)
@@ -147,28 +161,36 @@ local function render()
   center(1, "CREATE KRAFTWERK", colors.cyan)
   local firstRow = 3
   for index = 1, EXPECTED_BOILERS do
-    local state, speed, heatMode, color = readBoiler(speedometers[index], readers[index])
+    local state, heatMode, color = readBoiler(readers[index])
     local row = firstRow + index - 1
     if row <= height then
-      center(row, ("BOILER %d  %-7s  %5.1f RPM  %s")
-        :format(index, state, speed, heatMode), color)
+      center(row, ("BOILER %d  %-7s  %s")
+        :format(index, state, heatMode), color)
     end
   end
 
+  local speed = readMainSpeed(speedometers[1])
   local capacity, usage, load = readMainShaft(stressometers[1])
   if height >= 7 then center(7, "MAIN SHAFT", colors.cyan) end
+  if height >= 8 then
+    if speed then
+      center(8, ("Speed:    %.1f RPM"):format(speed), speed > 0 and colors.lime or colors.orange)
+    else
+      center(8, "Speedometer nicht gefunden", colors.red)
+    end
+  end
   if capacity then
-    if height >= 8 then center(8, "Capacity: " .. formatInteger(capacity) .. " SU", colors.white) end
-    if height >= 9 then center(9, "Usage:    " .. formatInteger(usage) .. " SU", colors.white) end
-    if height >= 10 then
+    if height >= 9 then center(9, "Capacity: " .. formatInteger(capacity) .. " SU", colors.white) end
+    if height >= 10 then center(10, "Usage:    " .. formatInteger(usage) .. " SU", colors.white) end
+    if height >= 11 then
       local loadText = ("Load:      %.1f %%"):format(load):gsub("%.", ",")
-      center(10, loadText, load >= 90 and colors.red or load >= 70 and colors.orange or colors.lime)
+      center(11, loadText, load >= 90 and colors.red or load >= 70 and colors.orange or colors.lime)
     end
   else
-    if height >= 8 then center(8, "Stressometer nicht gefunden", colors.red) end
+    if height >= 9 then center(9, "Stressometer nicht gefunden", colors.red) end
   end
 
-  if height >= 12 then
+  if height >= 13 then
     center(height, "Nur Anzeige - keine Steuerung", colors.gray)
   end