//#include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
#include <ArduinoModbus.h>
#include <Servo.h>

const int ledPin = LED_BUILTIN;

Servo myservo;

void setup()
{
  Serial.begin(9600);

  myservo.attach(4);
  // start the Modbus RTU server, with (slave) id 1
  if (!ModbusRTUServer.begin(1, 9600)) {
    Serial.println("Failed to start Modbus RTU Server!");
    while (1);
  }

  // configure the LED
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, HIGH);

  // configure a single coil at address 0x00
 // ModbusRTUServer.configureCoils(0x02, 1);
  ModbusRTUServer.configureCoils(0x04, 1);

}

void loop()
{
  // poll for Modbus RTU requests
  ModbusRTUServer.poll();

 /* // read the current value of the coil
  int coilValue = ModbusRTUServer.coilRead(0x02);

  if (coilValue) {
    // coil value set, turn LED on
    digitalWrite(ledPin, HIGH);
    digitalWrite(2, HIGH);
  } else {
    // coild value clear, turn LED off
    digitalWrite(ledPin, LOW);
    digitalWrite(2, LOW);
  }
*/
 int coilValueServo = ModbusRTUServer.coilRead(0x04);

if(coilValueServo==0)
 {
 myservo.write(0);
 }

if (coilValueServo==1)
{
  myservo.write(180);
}

if (coilValueServo==2)
{
  myservo.write(90);
}

}