#include <ModbusRTUSlave.h>
#include <Servo.h>

#define POTENTIOMETER_ADDRESS 0x00
#define SERVO_ADDRESS 0x01

#define POTENTIOMETER_PIN A0
#define SERVO_PIN 9

ModbusRTUSlave modbus;
Servo servo;

int potValue = 0;

void setup() {
  modbus.configure(9600, 1, 2, 3, 4); // Configure Modbus (baudrate, TX pin, RX pin, DERE pin, LED pin)
  modbus.addHreg(POTENTIOMETER_ADDRESS); // Add Holding Register for potentiometer value
  modbus.addHreg(SERVO_ADDRESS); // Add Holding Register for servo position
  servo.attach(SERVO_PIN); // Attach servo to pin
}

void loop() {
  modbus.task(); // Handle Modbus communication

  // Read potentiometer value
  int newPotValue = analogRead(POTENTIOMETER_PIN);
  if (newPotValue != potValue) {
    potValue = newPotValue;
    modbus.Hreg(POTENTIOMETER_ADDRESS, potValue); // Update Modbus register with new potentiometer value
  }

  // Read servo position from Modbus register and set servo position
  int servoPosition = modbus.Hreg(SERVO_ADDRESS);
  servo.write(map(servoPosition, 0, 65535, 0, 180)); // Map Modbus register value to servo position
}