diff --git a/.gitignore b/.gitignore
index 8f01818..6237359 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,16 +7,9 @@ Release/*
 .pio/
 .vscode/
 config.h
-.vscode/*
-# mySetup.h
 mySetup.cpp
 myHal.cpp
-# myAutomation.h
 myFilter.cpp
-# myAutomation.h
-# myLayout.h
 my*.h
 !my*.example.h
-.vscode/extensions.json
-.vscode/extensions.json
 compile_commands.json
diff --git a/.vscode/extensions.json b/.vscode/extensions.json
deleted file mode 100644
index 080e70d..0000000
--- a/.vscode/extensions.json
+++ /dev/null
@@ -1,10 +0,0 @@
-{
-    // See http://go.microsoft.com/fwlink/?LinkId=827846
-    // for the documentation about the extensions.json format
-    "recommendations": [
-        "platformio.platformio-ide"
-    ],
-    "unwantedRecommendations": [
-        "ms-vscode.cpptools-extension-pack"
-    ]
-}
diff --git a/.vscode/settings.json b/.vscode/settings.json
deleted file mode 100644
index ffa498a..0000000
--- a/.vscode/settings.json
+++ /dev/null
@@ -1,12 +0,0 @@
-{
-    "files.associations": {
-        "array": "cpp",
-        "deque": "cpp",
-        "string": "cpp",
-        "unordered_map": "cpp",
-        "vector": "cpp",
-        "string_view": "cpp",
-        "initializer_list": "cpp",
-        "cstdint": "cpp"
-    }
-}
diff --git a/Display.cpp b/Display.cpp
index 2c44778..a1a1ec1 100644
--- a/Display.cpp
+++ b/Display.cpp
@@ -1,5 +1,6 @@
 /*
  *  © 2021, Chris Harlow, Neil McKechnie. All rights reserved.
+ *  © 2023, Harald Barth.
  *
  *  This file is part of CommandStation-EX
  *
@@ -52,7 +53,7 @@ Display::Display(DisplayDevice *deviceDriver) {
   _deviceDriver = deviceDriver;
   // Get device dimensions in characters (e.g. 16x2).
   numCharacterColumns = _deviceDriver->getNumCols();
-  numCharacterRows = _deviceDriver->getNumRows();;
+  numCharacterRows = _deviceDriver->getNumRows();
   for (uint8_t row = 0; row < MAX_CHARACTER_ROWS; row++) 
     rowBuffer[row][0] = '\0';
   topRow = ROW_INITIAL;  // loop2 will fill from row 0
@@ -173,16 +174,18 @@ bool Display::findNextNonBlankRow() {
       rowNext = 0;
     else
       rowNext = rowNext + 1;
-    if (rowNext >= MAX_CHARACTER_ROWS) rowNext = ROW_INITIAL;
 #if SCROLLMODE == 1
-    // Finished if we've looped back to start
-    if (rowNext == ROW_INITIAL) {
+    if (rowNext >= MAX_CHARACTER_ROWS) {
+      // Finished if we've looped back to start
+      rowNext = ROW_INITIAL;
       noMoreRowsToDisplay = true;
       return false;
     }
 #else
-    // Finished if we're back to the first one shown
+    if (rowNext >= MAX_CHARACTER_ROWS)
+      rowNext = 0;
     if (rowNext == rowFirst) {
+      // Finished if we're back to the first one shown
       noMoreRowsToDisplay = true;
       return false;
     }
@@ -193,4 +196,4 @@ bool Display::findNextNonBlankRow() {
     }
   }
   return false;
-}
\ No newline at end of file
+}
diff --git a/EXRAIL2.cpp b/EXRAIL2.cpp
index 3bd8da7..8541cd2 100644
--- a/EXRAIL2.cpp
+++ b/EXRAIL2.cpp
@@ -105,12 +105,9 @@ uint16_t RMFT2::getOperand(byte n) {
 // getOperand static version, must be provided prog counter from loop etc.
 uint16_t RMFT2::getOperand(int progCounter,byte n) {
   int offset=progCounter+1+(n*3);
-  if (offset&1) {
-       byte lsb=GETHIGHFLASH(RouteCode,offset);
-       byte msb=GETHIGHFLASH(RouteCode,offset+1);
-       return msb<<8|lsb;
-  }
-  return GETHIGHFLASHW(RouteCode,offset);
+  byte lsb=GETHIGHFLASH(RouteCode,offset);
+  byte msb=GETHIGHFLASH(RouteCode,offset+1);
+  return msb<<8|lsb;
 }
 
 LookList::LookList(int16_t size) {
diff --git a/GITHUB_SHA.h b/GITHUB_SHA.h
index db56eac..be808f8 100644
--- a/GITHUB_SHA.h
+++ b/GITHUB_SHA.h
@@ -1 +1 @@
-#define GITHUB_SHA "devel-202303101548Z"
+#define GITHUB_SHA "devel-202303141949Z"
diff --git a/IO_EXIOExpander.h b/IO_EXIOExpander.h
index 0296c93..84433b7 100644
--- a/IO_EXIOExpander.h
+++ b/IO_EXIOExpander.h
@@ -154,12 +154,30 @@ private:
 
   // Main loop, collect both digital and analogue pin states continuously (faster sensor/input reads)
   void _loop(unsigned long currentMicros) override {
-    (void)currentMicros; // remove warning
-    if (_deviceState == DEVSTATE_FAILED) return;
-    _command1Buffer[0] = EXIORDD;
-    I2CManager.read(_i2cAddress, _digitalInputStates, _digitalPinBytes, _command1Buffer, 1, &_i2crb);
-    _command1Buffer[0] = EXIORDAN;
-    I2CManager.read(_i2cAddress, _analogueInputStates, _analoguePinBytes, _command1Buffer, 1, &_i2crb);
+    if (_deviceState == DEVSTATE_FAILED) return;    // If device failed, return
+    uint8_t status = _i2crb.status;
+    if (status == I2C_STATUS_PENDING) return;  // If device busy, return
+    if (status == I2C_STATUS_OK) {             // If device ok, read input data
+      if (_commandFlag) {
+        if (currentMicros - _lastDigitalRead > _digitalRefresh) { // Delay for digital read refresh
+          _lastDigitalRead = currentMicros;
+          _command1Buffer[0] = EXIORDD;
+          I2CManager.read(_i2cAddress, _digitalInputStates, _digitalPinBytes, _command1Buffer, 1, &_i2crb);
+        }
+      } else {
+        if (currentMicros - _lastAnalogueRead > _analogueRefresh) { // Delay for analogue read refresh
+          _lastAnalogueRead = currentMicros;
+          _command1Buffer[0] = EXIORDAN;
+          byte _tempAnalogue[_analoguePinBytes];      // Setup temp buffer so reads come from known state
+          I2CManager.read(_i2cAddress, _tempAnalogue, _analoguePinBytes, _command1Buffer, 1, &_i2crb);
+          memcpy(_analogueInputStates, _tempAnalogue, _analoguePinBytes); // Copy temp buffer to states
+        }
+      }
+      _commandFlag = !_commandFlag;
+    } else {
+      DIAG(F("EX-IOExpander I2C:%s Error:%d %S"), _I2CAddress.toString(), status, I2CManager.getErrorMessage(status));
+      _deviceState = DEVSTATE_FAILED;
+    }
   }
 
   // Obtain the correct analogue input value
@@ -191,9 +209,14 @@ private:
     _digitalOutBuffer[0] = EXIOWRD;
     _digitalOutBuffer[1] = pin;
     _digitalOutBuffer[2] = value;
-    I2CManager.read(_i2cAddress, _command1Buffer, 1, _digitalOutBuffer, 3, &_i2crb);
-    if (_command1Buffer[0] != EXIORDY) {
-      DIAG(F("Vpin %d cannot be used as a digital output pin"), (int)vpin);
+    uint8_t status = I2CManager.read(_i2cAddress, _command1Buffer, 1, _digitalOutBuffer, 3);
+    if (status != I2C_STATUS_OK) {
+      DIAG(F("EX-IOExpander I2C:%s Error:%d %S"), _I2CAddress.toString(), status, I2CManager.getErrorMessage(status));
+      _deviceState = DEVSTATE_FAILED;
+    } else {
+      if (_command1Buffer[0] != EXIORDY) {
+        DIAG(F("Vpin %d cannot be used as a digital output pin"), (int)vpin);
+      }
     }
   }
 
@@ -211,9 +234,14 @@ private:
     _servoBuffer[4] = profile;
     _servoBuffer[5] = duration & 0xFF;
     _servoBuffer[6] = duration >> 8;
-    I2CManager.read(_i2cAddress, _command1Buffer, 1, _servoBuffer, 7, &_i2crb);
-    if (_command1Buffer[0] != EXIORDY) {
-      DIAG(F("Vpin %d cannot be used as a servo/PWM pin"), (int)vpin);
+    uint8_t status = I2CManager.read(_i2cAddress, _command1Buffer, 1, _servoBuffer, 7);
+    if (status != I2C_STATUS_OK) {
+      DIAG(F("EX-IOExpander I2C:%s Error:%d %S"), _I2CAddress.toString(), status, I2CManager.getErrorMessage(status));
+      _deviceState = DEVSTATE_FAILED;
+    } else {
+      if (_command1Buffer[0] != EXIORDY) {
+        DIAG(F("Vpin %d cannot be used as a servo/PWM pin"), (int)vpin);
+      }
     }
   }
 
@@ -243,6 +271,11 @@ private:
   byte _servoBuffer[7];
   uint8_t* _analoguePinMap;
   I2CRB _i2crb;
+  bool _commandFlag = 1;
+  unsigned long _lastDigitalRead = 0;
+  unsigned long _lastAnalogueRead = 0;
+  const unsigned long _digitalRefresh = 10000UL;    // Delay refreshing digital inputs for 10ms
+  const unsigned long _analogueRefresh = 50000UL;   // Delay refreshing analogue inputs for 50ms
 
   // EX-IOExpander protocol flags
   enum {
diff --git a/Release_Notes/CommandRef.md b/Release_Notes/CommandRef.md
index 6420471..c06e388 100644
--- a/Release_Notes/CommandRef.md
+++ b/Release_Notes/CommandRef.md
@@ -4,24 +4,37 @@ General points:
   - Commands below have a single character opcode and parameters.
   Even <JA> is actually read as <J A> 
   - Keyword parameters are shown in upper case but may be entered in mixed case.
-  - value parameters are numeric.
+  - value parameters are decimal numeric (unless otherwise noted)
   - [something]  indicates its optional.
-  - Not all commands have a response, and not all responses come from the last commands that you have issued.
+  - Not all commands have a response, and broadcasts mean that not all responses come from the last commands that you have issued.
    
 Startup status
-<s>
+<s> Return status like
+    <iDCC-EX V-4.2.22 / MEGA / STANDARD_MOTOR_SHIELD G-devel-202302281422Z>
+    also returns defined turnout list:
+    <H id 1|0>   1=thrown
 
-Track power management
-<1>
-<1 MAIN|PROG|JOIN>
-<0>
-<0 MAIN|PROG>
+Track power management. After power commands a power state is broadcast to all throttles.
+
+<1>                Power on all
+<1 MAIN|PROG|JOIN> Power on MAIN or PROG track
+<1 JOIN>           Power on MAIN and PROG track but send main track data on both.
+<0>                Power off all tracks 
+<0 MAIN|PROG>      Power off main or prog track
+
+Basic manual loco control
+<t locoid speed direction>  Throttle loco. 
+    speed in JMRI-form  (-1=ESTOP, 0=STOP, 1..126 = DCC speeds 2..127)
+    direction 1=forward, 0=reverse
+    For response see broadcast <l>
+
+<F locoid function 1|0>     Set loco function 1=ON, 0-OFF
+    For response see broadcast <l>
+
+<!>  emergency stop all locos
+<T id 0|1|T|C>  Control turnout id, 0=C=Closed, 1=T=Thrown
+       response broadcast <H id 0|1>
 
-Basic manual control
-<t cab speed direction> 
-<F cab function 1|0>
-<!>
-<T id 0|1|T|C>
 
 DCC accessory control
 <a address subaddress activate [onoff]>
@@ -35,25 +48,30 @@ Note: Turnouts are best defined in myAutomation.h where a turnout description ca
 <T id VPIN vpin>
 <T id DCC addr subaddr>
 <T id DCC linearaddr>
+   Valid commands respond with <O>
+
+Outputs (Used by JMRI, not required by EXRAIL)
+<Z id vpin active>   Define an output pin that JMRI can set by id 
+<Z id activate>      Activate an output pin by id
 
 
-Outputs
-<Z id activate>
-<Z id vpin iflag>
+Sensors (Used by JMRI, not required by EXRAIL)
+<S id vpin pullup> define a sensor to be monitored.
+   Responses <Q id> and <q id> as sensor changes  
 
-Sensors 
-<S id vpin pullup>
+Decoder programming - main track
+<w cab cv value> POM write value to cv on loco
+<b cab cv bit value> POM write bit to cv on loco
 
-Decoder programming
-<w cab cv value>
-<b cab cv bit value>
-<W cabid>
-<W cv value>
-<V cv value>
-<V cv bit value>
-<R>
-<R cv>
-<B cv bit value>
+Decoder Programming - prog track
+<W cabid>  Clear consist and write new cab id (includes long/short settings)
+           Responds <W cabid> or <W -1> for error
+<W cv value> Write value to cv
+
+<V cv predictedValue> Read cv value, much faster if prediction is correct. 
+<V cv bit predictedValue>      Read CV bit
+
+<R>         Read drive-away loco id. (May be a consist id)
 <D ACK ON|OFF>
 <D ACK LIMIT|MIN|MAX|RETRY value>
 <D PROGBOOST>
@@ -152,6 +170,8 @@ Obsolete commands/formats
 <B cv bit value obsolete obsolete>
 <R cv obsolete obsolete>
 <W cv value obsolete obsolete>
+<R cv>            V command is much faster if prediction is correct.
+<B cv bit value>  V command is much faster if prediction is correct.
 
 Broadcast responses
 Note: broadcasts are sent to all throttles when appropriate (usually because something has changed)
diff --git a/version.h b/version.h
index 6e2d0ba..b8f547f 100644
--- a/version.h
+++ b/version.h
@@ -4,8 +4,14 @@
 #include "StringFormatter.h"
 
 
-#define VERSION "4.2.24"
-// 4.3.24 - Bugfix Ethernet shield: Static IP now possible
+#define VERSION "4.2.27"
+// 4.2.27 - Bugfix LCD showed random characters in SCROLLMODE 2
+// 4.2.26 - EX-IOExpander device driver enhancements
+//        - Enhance I2C error checking
+//        - Introduce delays to _loop to allow room for other I2C device comms
+//        - Improve analogue read reliability
+// 4.2.25 - Bugfix SAMD21 Exrail odd byte boundary
+// 4.2.24 - Bugfix Ethernet shield: Static IP now possible
 // 4.2.23 - Bugfix signalpin2 was not set up in shadow port
 // 4.2.22 - Implement broadcast of Track Manager changes
 // 4.2.21 - Implement non-blocking I2C for EX-IOExpander device driver