Lamp.ino

/**
    @file Lamp.ino
    Modbus-Arduino Example - Lamp (Modbus Serial)
    Copyright (C) 2023 Pascal JEAN aka epsilonrt
    Copyright (C) 2014 André Sarmento Barbosa
    https://github.com/epsilonrt/modbus-serial
*/

#include <ModbusSerial.h>

// Used Pins
const int LedPin = 13; // Change that to match your led
const int TxenPin = -1; // -1 disables the feature, change that if you are using an RS485 driver, this pin would be connected to the DE and /RE pins of the driver.

const byte SlaveId = 10;
// Modbus Registers Offsets (0-9999)
const int Lamp1Coil = 0;

#define MySerial Serial // define serial port used, Serial most of the time, or Serial1, Serial2 ... if available
const unsigned long Baudrate = 38400;

// ModbusSerial object
ModbusSerial mb (MySerial, SlaveId, TxenPin);

void setup() {

  MySerial.begin (Baudrate); // works on all boards but the configuration is 8N1 which is incompatible with the MODBUS standard
  // prefer the line below instead if possible
  // MySerial.begin (Baudrate, MB_PARITY_EVEN);
  
  mb.config (Baudrate);
  mb.setAdditionalServerData ("LAMP"); // for Report Server ID function (0x11)

  // Set LedPin mode
  pinMode (LedPin, OUTPUT);
  // Add Lamp1Coil register - Use addCoil() for digital outputs
  mb.addCoil (Lamp1Coil);
}

void loop() {
  
  // Call once inside loop() - all magic here
  mb.task();

  // Attach LedPin to Lamp1Coil register
  digitalWrite (LedPin, mb.Coil (Lamp1Coil));
}