I am trying to change the analog high and low registers. After writing code with Arduino IDE that creates the client and then attempts to write to the registers, I receive a timeout error. I thought it could be a register offset issue by I have no luck with that. I am able to compile the code and send it to the PLC but when the write command is given, I receive the error. I have included my code below. The exact error reads: Failed to write heater-1 for Analog High Adjustment Connection timed out". Any help would be appreciated.

#include <P1AM.h>

#include <ArduinoRS485.h>

#include <ArduinoModbus.h>

 #define HEATER_1_ADDRESS 1

 #define HEATER_2_ADDRESS 2

 #define HEATER_3_ADDRESS 3

 #define HEATER_4_ADDRESS 4

 #define ON_LINE_CONFIGURATION_ADDR 2065

 #define ANALOG_HIGH_ADJUSTMENT_ADDR 0xAC55//44117

 #define ANALOG_LOW_ADJUSTMENT_ADDR 44118

 #define OUTOUT_1_LEVEL_ADDR 44115

 #define HEATING_PERIOD_ADDR 1

 unsigned long long data;

void setup() {

  Serial.begin(9600);

  while (!Serial);

  Serial.println("Modbus RTU Client Toggle");

  // start the Modbus RTU client

  if (!ModbusRTUClient.begin(9600)) {

    Serial.println("Failed to start Modbus RTU Client!");

    while (1);

  }

  // for (heater) id 1: write the value of 0x14ED which is 5357 * 2.8uA or ~15mA,

  // to the holding register at address 0xAC55 for Analog High Adjustment

  if (!ModbusRTUClient.holdingRegisterWrite(HEATER_1_ADDRESS, ANALOG_HIGH_ADJUSTMENT_ADDR, 0x0000)) {

    Serial.print("Failed to write Failed to write heater-1 for Analog High Adjustment");

    Serial.println(ModbusRTUClient.lastError());

  }

}