added methods to configure modbus server to existing data stuctures

examples/TCP/EthernetModbusServerPointerMapping/EthernetModbusServerPointerMapping.ino

@@ -0,0 +1,129 @@
+/*
+  Ethernet Modbus TCP Server LED using existing variables as modbus memory
+
+  This sketch creates a Modbus TCP Server with a simulated coil.
+  The value of the simulated coil is set on the LED
+
+  Circuit:
+   - Any Arduino MKR Board
+   - MKR ETH Shield
+
+  created 16 July 2018
+  by Sandeep Mistry
+*/
+
+#include <SPI.h>
+#include <Ethernet.h>
+
+#include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
+#include <ArduinoModbus.h>
+
+// Enter a MAC address for your controller below.
+// Newer Ethernet shields have a MAC address printed on a sticker on the shield
+// The IP address will be dependent on your local network:
+byte mac[] = {
+  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
+};
+IPAddress ip(192, 168, 1, 177);
+
+EthernetServer ethServer(502);
+
+ModbusTCPServer modbusTCPServer;
+
+const int ledPin = LED_BUILTIN;
+
+//create an example struct of a modbus memory map
+struct mb_context{
+	uint8_t coils[10];
+	uint8_t inputStats[10];
+	uint16_t inputRegs[10];
+	uint16_t holdingRegs[10];
+};
+
+mb_context myModbusMap;
+
+void updateLED() {
+	// read the current value of the coil
+
+
+	if (myModbusMap.coils[0]) {
+		// coil value set, turn LED on
+		digitalWrite(ledPin, HIGH);
+		} else {
+		// coild value clear, turn LED off
+		digitalWrite(ledPin, LOW);
+	}
+}
+
+void setup() {
+  // You can use Ethernet.init(pin) to configure the CS pin
+  //Ethernet.init(10);  // Most Arduino shields
+  //Ethernet.init(5);   // MKR ETH shield
+  //Ethernet.init(0);   // Teensy 2.0
+  //Ethernet.init(20);  // Teensy++ 2.0
+  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
+  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet
+
+  // Open serial communications and wait for port to open:
+  Serial.begin(9600);
+  while (!Serial) {
+    ; // wait for serial port to connect. Needed for native USB port only
+  }
+  Serial.println("Ethernet Modbus TCP Example");
+
+  // start the Ethernet connection and the server:
+  Ethernet.begin(mac, ip);
+
+  // Check for Ethernet hardware present
+  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
+    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
+    while (true) {
+      delay(1); // do nothing, no point running without Ethernet hardware
+    }
+  }
+  if (Ethernet.linkStatus() == LinkOFF) {
+    Serial.println("Ethernet cable is not connected.");
+  }
+
+  // start the server
+  ethServer.begin();
+
+  // start the Modbus TCP server
+  if (!modbusTCPServer.begin()) {
+    Serial.println("Failed to start Modbus TCP Server!");
+    while (1);
+  }
+
+  // configure the LED
+  pinMode(ledPin, OUTPUT);
+  digitalWrite(ledPin, LOW);
+
+  // configure a each modbus table's pointer and length
+  modbusTCPServer.configureCoilPointer(myModbusMap.coils, 0x00, 10);
+  modbusTCPServer.configureDiscreteInputPointer(myModbusMap.inputStats, 0x00, 10);
+  modbusTCPServer.configureInputRegisterPointer(myModbusMap.inputRegs, 0x00, 10);
+  modbusTCPServer.configureHoldingRegisterPointer(myModbusMap.holdingRegs, 0x00, 10);
+}
+
+void loop() {
+  // listen for incoming clients
+  EthernetClient client = ethServer.available();
+
+  if (client) {
+    // a new client connected
+    Serial.println("new client");
+
+    // let the Modbus TCP accept the connection 
+    modbusTCPServer.accept(client);
+
+    while (client.connected()) {
+      // poll for Modbus TCP requests, while client connected
+      modbusTCPServer.poll();
+
+      // update the LED
+      updateLED();
+    }
+
+    Serial.println("client disconnected");
+  }
+}

src/ModbusServer.cpp

@@ -50,6 +50,21 @@ ModbusServer::~ModbusServer()
   }
 }
 
+int ModbusServer::configureCoilPointer(uint8_t *ptr, int startAddress, int nb)
+{
+  if (startAddress < 0 || nb < 1) {
+  errno = EINVAL;
+
+  return -1;
+  }
+
+  _mbMapping.tab_bits = ptr;
+  _mbMapping.start_bits = startAddress;
+  _mbMapping.nb_bits = nb;
+
+  return 1;
+}
+
 int ModbusServer::configureCoils(int startAddress, int nb)
 {
   if (startAddress < 0 || nb < 1) {
@@ -76,6 +91,20 @@ int ModbusServer::configureCoils(int startAddress, int nb)
   return 1;
 }
 
+int ModbusServer::configureDiscreteInputPointer(uint8_t *ptr, int startAddress, int nb)
+{
+  if (startAddress < 0 || nb < 1) {
+  errno = EINVAL;
+
+  return -1;
+  }
+  _mbMapping.tab_input_bits = ptr;
+  _mbMapping.start_input_bits = startAddress;
+  _mbMapping.nb_input_bits = nb;
+
+  return 1;
+}
+
 int ModbusServer::configureDiscreteInputs(int startAddress, int nb)
 {
   if (startAddress < 0 || nb < 1) {
@@ -102,6 +131,19 @@ int ModbusServer::configureDiscreteInputs(int startAddress, int nb)
   return 1;
 }
 
+int ModbusServer::configureHoldingRegisterPointer(uint16_t *ptr, int startAddress, int nb)
+  {
+  if (startAddress < 0 || nb < 1) {
+  errno = EINVAL;
+
+  return -1;
+  }
+  _mbMapping.tab_registers = ptr;
+  _mbMapping.start_registers = startAddress;
+  _mbMapping.nb_registers = nb;
+  return 1;
+}
+
 int ModbusServer::configureHoldingRegisters(int startAddress, int nb)
 {
   if (startAddress < 0 || nb < 1) {
@@ -128,6 +170,20 @@ int ModbusServer::configureHoldingRegisters(int startAddress, int nb)
   return 1;
 }
 
+int ModbusServer::configureInputRegisterPointer(uint16_t *ptr, int startAddress, int nb)
+  {
+  if (startAddress < 0 || nb < 1) {
+  errno = EINVAL;
+
+  return -1;
+  }
+  _mbMapping.tab_input_registers = ptr;
+  _mbMapping.start_input_registers = startAddress;
+  _mbMapping.nb_input_registers = nb;
+
+  return 1;
+}
+
 int ModbusServer::configureInputRegisters(int startAddress, int nb)
 {
   if (startAddress < 0 || nb < 1) {

src/ModbusServer.h

@@ -29,6 +29,17 @@ extern "C" {
 class ModbusServer {
 
 public:
+    /**
+  * Configure the servers coil starting address.
+  *
+  * @param ptr pointer address of existing data struct
+  * @param startAddress start address of holding registers
+  * @param nb number of holding registers to configure
+  *
+  * @return 0 on success, 1 on failure
+  */
+  int configureCoilPointer(uint8_t *ptr, int startAddress, int nb);
+
   /**
    * Configure the servers coils.
    *
@@ -39,6 +50,17 @@ class ModbusServer {
    */
   int configureCoils(int startAddress, int nb);
 
+  /**
+  * Configure the servers discrete inputs starting address.
+  *
+  * @param ptr pointer address of existing data struct
+  * @param startAddress start address of holding registers
+  * @param nb number of holding registers to configure
+  *
+  * @return 0 on success, 1 on failure
+  */
+  int configureDiscreteInputPointer(uint8_t *ptr, int startAddress, int nb);
+
   /**
    * Configure the servers discrete inputs.
    *
@@ -49,6 +71,17 @@ class ModbusServer {
    */
   int configureDiscreteInputs(int startAddress, int nb);
 
+  /**
+  * Configure the servers holding registers starting address.
+  *
+  * @param ptr pointer address of existing data struct
+  * @param startAddress start address of holding registers
+  * @param nb number of holding registers to configure
+  *
+  * @return 0 on success, 1 on failure
+  */
+  int configureHoldingRegisterPointer(uint16_t *ptr, int startAddress, int nb);
+
   /**
    * Configure the servers holding registers.
    *
@@ -59,6 +92,17 @@ class ModbusServer {
    */
   int configureHoldingRegisters(int startAddress, int nb);
 
+  /**
+  * Configure the servers input registers starting address.
+  *
+  * @param ptr pointer address of existing data struct
+  * @param startAddress start address of holding registers
+  * @param nb number of holding registers to configure
+  *
+  * @return 0 on success, 1 on failure
+  */
+  int configureInputRegisterPointer(uint16_t *ptr, int startAddress, int nb);
+
   /**
    * Configure the servers input registers.
    *