diff --git a/IO_ExampleSerial.cpp b/IO_ExampleSerial.cpp
deleted file mode 100644
index 12476db..0000000
--- a/IO_ExampleSerial.cpp
+++ /dev/null
@@ -1,129 +0,0 @@
-/*
- *  © 2021, Neil McKechnie. All rights reserved.
- *  
- *  This file is part of DCC++EX API
- *
- *  This is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  It is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-#include <Arduino.h>
-#include "IO_ExampleSerial.h"
-#include "FSH.h"
-
-// Constructor
-IO_ExampleSerial::IO_ExampleSerial(VPIN firstVpin, int nPins, HardwareSerial *serial, unsigned long baud) {
-  _firstVpin = firstVpin;
-  _nPins = nPins;
-  _pinValues = (uint16_t *)calloc(_nPins, sizeof(uint16_t));
-  _baud = baud;
-  
-  // Save reference to serial port driver
-  _serial = serial;
-
-  addDevice(this);
-}
-
-// Static create method for one module.
-void IO_ExampleSerial::create(VPIN firstVpin, int nPins, HardwareSerial *serial, unsigned long baud) {
-  if (checkNoOverlap(firstVpin,nPins)) new IO_ExampleSerial(firstVpin, nPins, serial, baud);
-}
-
-// Device-specific initialisation
-void IO_ExampleSerial::_begin() {
-  _serial->begin(_baud);
-#if defined(DIAG_IO)
-  _display();
-#endif
-
-  // Send a few # characters to the output
-  for (uint8_t i=0; i<3; i++)
-    _serial->write('#');
-}
-
-// Device-specific write function.  Write a string in the form "#Wm,n#"
-//  where m is the vpin number, and n is the value.
-void IO_ExampleSerial::_write(VPIN vpin, int value) {
-  int pin = vpin -_firstVpin;
-  #ifdef DIAG_IO
-  DIAG(F("IO_ExampleSerial::_write Pin:%d Value:%d"), (int)vpin, value);
-  #endif
-  // Send a command string over the serial line
-  _serial->print('#');
-  _serial->print('W');
-  _serial->print(pin);
-  _serial->print(',');
-  _serial->print(value);
-  _serial->println('#');
-  DIAG(F("ExampleSerial Sent command, p1=%d, p2=%d"), vpin, value);
- }
-
-// Device-specific read function.
-int IO_ExampleSerial::_read(VPIN vpin) {
-
-  // Return a value for the specified vpin.
-  int result = _pinValues[vpin-_firstVpin];
-
-  return result;
-}
-
-// Loop function to do background scanning of the input port.  State 
-//  machine parses the incoming command as it is received.  Command
-//  is in the form "#Nm,n#" where m is the index and n is the value.
-void IO_ExampleSerial::_loop(unsigned long currentMicros) {
-  (void)currentMicros;  // Suppress compiler warnings
-  if (_serial->available()) {
-    // Input data available to read.  Read a character.
-    char c = _serial->read();
-    switch (_inputState) {
-      case 0: // Waiting for start of command
-        if (c == '#')  // Start of command received.
-          _inputState = 1;
-        break;
-      case 1: // Expecting command character
-        if (c == 'N') { // 'Notify' character received
-          _inputState = 2;
-          _inputValue = _inputIndex = 0;
-        } else
-          _inputState = 0; // Unexpected char, reset
-        break;
-      case 2: // reading first parameter (index)
-        if (isdigit(c))
-          _inputIndex = _inputIndex * 10 + (c-'0');
-        else if (c==',') 
-          _inputState = 3;
-        else
-          _inputState = 0; // Unexpected char, reset
-        break;
-      case 3: // reading reading second parameter (value)
-        if (isdigit(c)) 
-          _inputValue = _inputValue * 10 - (c-'0');
-        else if (c=='#') { // End of command
-          // Complete command received, do something with it.
-          DIAG(F("ExampleSerial Received command, p1=%d, p2=%d"), _inputIndex, _inputValue);
-          if (_inputIndex < _nPins) { // Store value
-            _pinValues[_inputIndex] = _inputValue;
-          }
-          _inputState = 0; // Done, start again.
-        } else
-          _inputState = 0; // Unexpected char, reset
-        break;
-    }
-  }
-}
-
-void IO_ExampleSerial::_display() {
-  DIAG(F("IO_ExampleSerial Configured on VPins:%d-%d"), (int)_firstVpin, 
-    (int)_firstVpin+_nPins-1);
-}
-
diff --git a/IO_ExampleSerial.h b/IO_ExampleSerial.h
index 9b20399..da421c5 100644
--- a/IO_ExampleSerial.h
+++ b/IO_ExampleSerial.h
@@ -35,24 +35,131 @@
 #include "IODevice.h"
 
 class IO_ExampleSerial : public IODevice {
-public:
-  static void create(VPIN firstVpin, int nPins, HardwareSerial *serial, unsigned long baud);  
-
-protected:
-  IO_ExampleSerial(VPIN firstVpin, int nPins, HardwareSerial *serial, unsigned long baud);
-  void _begin() override;
-  void _loop(unsigned long currentMicros) override;
-  void _write(VPIN vpin, int value) override;
-  int _read(VPIN vpin) override;
-  void _display() override;
-
 private:
+  // Here we define the device-specific variables.  
   HardwareSerial *_serial;
   uint8_t _inputState = 0;
   int _inputIndex = 0;
   int _inputValue = 0;
   uint16_t *_pinValues; // Pointer to block of memory containing pin values
   unsigned long _baud;
+
+public:
+  //  Static function to handle "IO_ExampleSerial::create(...)" calls.
+  static void create(VPIN firstVpin, int nPins, HardwareSerial *serial, unsigned long baud) {
+    if (checkNoOverlap(firstVpin,nPins)) new IO_ExampleSerial(firstVpin, nPins, serial, baud);
+  } 
+
+protected:
+  // Constructor.  This should initialise variables etc. but not call other objects yet
+  // (e.g. Serial, I2CManager, and other parts of the CS functionality).
+  // defer those until the _begin() function.  The 'addDevice' call is required unless
+  // the device is not to be added (e.g. because of incorrect parameters).
+  IO_ExampleSerial(VPIN firstVpin, int nPins, HardwareSerial *serial, unsigned long baud) {
+    _firstVpin = firstVpin;
+    _nPins = nPins;
+    _pinValues = (uint16_t *)calloc(_nPins, sizeof(uint16_t));
+    _baud = baud;
+    
+    // Save reference to serial port driver
+    _serial = serial;
+
+    addDevice(this);
+  }
+
+  // Device-specific initialisation
+  void _begin() override {
+    _serial->begin(_baud);
+#if defined(DIAG_IO)
+    _display();
+#endif
+
+    // Send a few # characters to the output
+    for (uint8_t i=0; i<3; i++)
+      _serial->write('#');
+  }
+  
+  // Device-specific write function.  Write a string in the form "#Wm,n#"
+  //  where m is the vpin number, and n is the value.
+  void _write(VPIN vpin, int value) {
+    int pin = vpin -_firstVpin;
+    #ifdef DIAG_IO
+    DIAG(F("IO_ExampleSerial::_write Pin:%d Value:%d"), (int)vpin, value);
+    #endif
+    // Send a command string over the serial line
+    _serial->print('#');
+    _serial->print('W');
+    _serial->print(pin);
+    _serial->print(',');
+    _serial->print(value);
+    _serial->println('#');
+    DIAG(F("ExampleSerial Sent command, p1=%d, p2=%d"), vpin, value);
+  }
+
+  // Device-specific read function.
+  int _read(VPIN vpin) {
+
+    // Return a value for the specified vpin.
+    int result = _pinValues[vpin-_firstVpin];
+
+    return result;
+  }
+
+  // Loop function to do background scanning of the input port.  State 
+  //  machine parses the incoming command as it is received.  Command
+  //  is in the form "#Nm,n#" where m is the index and n is the value.
+  void _loop(unsigned long currentMicros) {
+    (void)currentMicros;  // Suppress compiler warnings
+    if (_serial->available()) {
+      // Input data available to read.  Read a character.
+      char c = _serial->read();
+      switch (_inputState) {
+        case 0: // Waiting for start of command
+          if (c == '#')  // Start of command received.
+            _inputState = 1;
+          break;
+        case 1: // Expecting command character
+          if (c == 'N') { // 'Notify' character received
+            _inputState = 2;
+            _inputValue = _inputIndex = 0;
+          } else
+            _inputState = 0; // Unexpected char, reset
+          break;
+        case 2: // reading first parameter (index)
+          if (isdigit(c))
+            _inputIndex = _inputIndex * 10 + (c-'0');
+          else if (c==',') 
+            _inputState = 3;
+          else
+            _inputState = 0; // Unexpected char, reset
+          break;
+        case 3: // reading reading second parameter (value)
+          if (isdigit(c)) 
+            _inputValue = _inputValue * 10 - (c-'0');
+          else if (c=='#') { // End of command
+            // Complete command received, do something with it.
+            DIAG(F("ExampleSerial Received command, p1=%d, p2=%d"), _inputIndex, _inputValue);
+            if (_inputIndex >= 0 && _inputIndex < _nPins) { // Store value
+              _pinValues[_inputIndex] = _inputValue;
+            }
+            _inputState = 0; // Done, start again.
+          } else
+            _inputState = 0; // Unexpected char, reset
+          break;
+      }
+    }
+  }
+
+  // Display information about the device, and perhaps its current condition (e.g. active, disabled etc).
+  // Here we display the current values held for the pins.
+  void _display() {
+    DIAG(F("IO_ExampleSerial Configured on VPins:%d-%d"), (int)_firstVpin, 
+      (int)_firstVpin+_nPins-1);
+    for (int i=0; i<_nPins; i++)
+      DIAG(F("  VPin %2d: %d"), _firstVpin+i, _pinValues[i]);
+  }
+
+
 };
 
 #endif // IO_EXAMPLESERIAL_H
\ No newline at end of file