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added methods to configure modbus server's tables to existing data structs and example
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3 files changed

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‎examples/TCP/EthernetModbusServerPointerMapping/EthernetModbusServerPointerMapping.ino

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

‎src/ModbusServer.cpp

Lines changed: 57 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -50,6 +50,21 @@ ModbusServer::~ModbusServer()
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}
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}
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int ModbusServer::configureCoilPointer(uint8_t *ptr, int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
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errno = EINVAL;
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return -1;
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}
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_mbMapping.tab_bits = ptr;
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_mbMapping.start_bits = startAddress;
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_mbMapping.nb_bits = nb;
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return 1;
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}
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int ModbusServer::configureCoils(int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
@@ -76,6 +91,20 @@ int ModbusServer::configureCoils(int startAddress, int nb)
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return 1;
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}
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int ModbusServer::configureDiscreteInputPointer(uint8_t *ptr, int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
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errno = EINVAL;
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return -1;
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}
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_mbMapping.tab_input_bits = ptr;
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_mbMapping.start_input_bits = startAddress;
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_mbMapping.nb_input_bits = nb;
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return 1;
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}
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int ModbusServer::configureDiscreteInputs(int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
@@ -102,6 +131,20 @@ int ModbusServer::configureDiscreteInputs(int startAddress, int nb)
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return 1;
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}
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int ModbusServer::configureHoldingRegisterPointer(uint16_t *ptr, int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
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errno = EINVAL;
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return -1;
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}
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_mbMapping.tab_registers = ptr;
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_mbMapping.start_registers = startAddress;
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_mbMapping.nb_registers = nb;
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return 1;
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}
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int ModbusServer::configureHoldingRegisters(int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
@@ -128,6 +171,20 @@ int ModbusServer::configureHoldingRegisters(int startAddress, int nb)
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return 1;
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}
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int ModbusServer::configureInputRegisterPointer(uint16_t *ptr, int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {
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errno = EINVAL;
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return -1;
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}
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_mbMapping.tab_input_registers = ptr;
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_mbMapping.start_input_registers = startAddress;
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_mbMapping.nb_input_registers = nb;
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return 1;
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}
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int ModbusServer::configureInputRegisters(int startAddress, int nb)
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{
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if (startAddress < 0 || nb < 1) {

‎src/ModbusServer.h

Lines changed: 46 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,16 @@ extern "C" {
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class ModbusServer {
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public:
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/**
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* Configure the servers coil starting address.
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*
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* @param ptr pointer address of existing data struct
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* @param startAddress start address of holding registers
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* @param nb number of holding registers to configure
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*
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* @return 0 on success, 1 on failure
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*/
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int configureCoilPointer(uint8_t *ptr, int startAddress, int nb);
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/**
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* Configure the servers coils.
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*
@@ -38,7 +48,16 @@ class ModbusServer {
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* @return 0 on success, 1 on failure
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*/
4050
int configureCoils(int startAddress, int nb);
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/**
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* Configure the servers discrete inputs starting address.
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*
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* @param ptr pointer address of existing data struct
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* @param startAddress start address of holding registers
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* @param nb number of holding registers to configure
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*
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* @return 0 on success, 1 on failure
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*/
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int configureDiscreteInputPointer(uint8_t *ptr, int startAddress, int nb);
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/**
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* Configure the servers discrete inputs.
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*
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*/
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int configureDiscreteInputs(int startAddress, int nb);
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/**
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* Configure the servers holding registers.
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* Configure the servers holding registers starting address.
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*
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* @param ptr pointer address of existing data struct
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* @param startAddress start address of holding registers
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* @param nb number of holding registers to configure
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*
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* @return 0 on success, 1 on failure
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*/
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int configureHoldingRegisterPointer(uint16_t *ptr, int startAddress, int nb);
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/**
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* Configure the servers holding registers.
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*
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* @param startAddress start address of holding registers
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* @param nb number of holding registers to configure
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*
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* @return 0 on success, 1 on failure
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*/
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int configureHoldingRegisters(int startAddress, int nb);
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/**
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* Configure the servers input registers starting address.
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*
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* @param ptr pointer address of existing data struct
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* @param startAddress start address of holding registers
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* @param nb number of holding registers to configure
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*
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* @return 0 on success, 1 on failure
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*/
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int configureInputRegisterPointer(uint16_t *ptr, int startAddress, int nb);
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/**
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* Configure the servers input registers.
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*
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* @return 0 on success, 1 on failure
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*/
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int configureInputRegisters(int startAddress, int nb);
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// same as ModbusClient.h

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