ModBus_Slave_Teste

  #include <SimpleModbusSlave.h>
  #define  LED 9
  #define  LUZ 13

  enum
  {
    ADC_VAL,
    LUZ_VAL,
    XPTO_VAL,
    HOLDING_REGS_SIZE // leave this one
  };

  unsigned int holdingRegs[HOLDING_REGS_SIZE]; // function 3 and 16 register array

  void setup()
  {
    modbus_configure(&Serial, 9600, SERIAL_8N2, 1, 2, HOLDING_REGS_SIZE, holdingRegs);
    modbus_update_comms(9600, SERIAL_8N2, 2);
    pinMode(LED, OUTPUT);
    pinMode(LUZ, INPUT_PULLUP);
  }

  void loop()
  {
    modbus_update();
    holdingRegs[ADC_VAL] = analogRead(A0); // update data to be read by the master to adjust the PWM
    holdingRegs[LUZ_VAL] = digitalRead(13); // update data to be read by the master to adjust the PWM
  //  holdingRegs[LUZ_VAL] = analogRead(A1); // update data to be read by the master to adjust the PWM
    holdingRegs[XPTO_VAL] = 0x0228; // update data to be read by the master to adjust the PWM
  }