URM14-RS485 Ultrasound sensor problem with Arduino IDE

I've gathered all the necessary equipment for the DFRobot's URM14 sensor as indicated in their sample code. Despite this, I consistently face a timeout error when I invoke the holdingRegisterWrite() or requestFrom() methods from the ModbusRTUClient class, even when addressing the default Public address 0x00. Would you be able to assist me, M. Yeez_B? Below are the code snippets and the corresponding output from the serial monitor that I am working with.

[code]
/**************************************************************************************************************
    This code tests the address modification function of the URM14 ultrasonic sensor
    @ author : [email protected]
    @ data   : 11.08.2020
    @ version: 1.0
    RX(TTL-RS485转接板) -> TX1/D1 （Arduino Leonardo）  TX（TTL-RS485转接板）-> RX1/D0 （Arduino Leonardo）
**************************************************************************************************************/
#include <ArduinoModbus.h>
#include <ArduinoRS485.h>

#define   PUBLIC_ADDR               ((uint16_t)0x00)
#define   SLAVE_ADDR                ((uint16_t)0x14)

#define   TEMP_CPT_SEL_BIT          ((uint16_t)0x01)
#define   TEMP_CPT_ENABLE_BIT       ((uint16_t)0x01 << 1)
#define   MEASURE_MODE_BIT          ((uint16_t)0x01 << 2)
#define   MEASURE_TRIG_BIT          ((uint16_t)0x01 << 3)

typedef enum{ 
 /*0*/ePid,
 /*1*/eVid,
 /*2*/eAddr, //The Module Address Register, used for setting the sensor's address on the network, can be read and written to.
 /*3*/eComBaudrate,//Serial Parameter Control Registers configure communication parameters like baud rate and parity
 /*4*/eComParityStop,//...
 /*5*/eDistance, //The Distance Register stores the measurement result from the sensor.
 /*6*/eInternalTempreture,//Onboard Temperature Data Register provides the internal temperature
 /*7*/eExternTempreture,//The External Temperature Compensation Data Register allows for temperature compensation to improve accuracy.
 /*8*/eControl,//The Control Register, which controls measurement triggering and operating modes.
 /*9*/eNoise //Electrical Noise Level Register indicates the noise level affecting measurements.
}eRegIndex_t;//Sensor register index

/*
*@brief Read data from holding register of client
*
*@param addr ： Address of Client
*@param reg: Reg index
*@return data if execute successfully, false oxffff.
*/
uint16_t readData(uint16_t addr, eRegIndex_t reg)
{
 uint16_t data;
 if (!ModbusRTUClient.requestFrom(addr, HOLDING_REGISTERS, reg, 1)){
   Serial.print("failed to read registers! ");
   Serial.println(ModbusRTUClient.lastError());
   data = 0xffff;
 }else{
   data =  ModbusRTUClient.read();
 }
 return data;
}

/*
*@brief write data to holding register of client 
*
*@param addr ： Address of Client
*@param reg: Reg index
*@param data: The data to be written
*@return 1 if execute successfully, false 0.
*/

uint16_t writeData(uint16_t addr, eRegIndex_t reg, uint16_t data)
{
 if (!ModbusRTUClient.holdingRegisterWrite(addr, reg, data)){
   Serial.print("Failed to write coil! ");
   Serial.println(ModbusRTUClient.lastError());
   return 0;
 }else
   return 1;
}

float  dist;
volatile uint16_t cr = 0;

void setup() {
 Serial.begin(9600);
 ModbusRTUClient.begin(19200);
 delay(3000);
}
volatile uint16_t newAddr, res;

void loop() {
 
 //newAddr = 0x14;
 //res = writeData(PUBLIC_ADDR, eAddr, newAddr);//Writes the new address value to the register
 //if (res)Serial.println("finally I can write");
 //Serial.print("The device address has been modified as ");
 //Serial.print(newAddr);
 //Serial.println(".please reset the device!");
 //while (1);
 cr |= MEASURE_TRIG_BIT;//Set trig bit = 8 to trigger a measurement. 
 writeData(PUBLIC_ADDR, eControl, cr); //Write the value to the control register and trigger a ranging ONCE
 delay(31);//Delay of 300ms(minimum delay should be greater than 30ms) is to wait for the completion of ranging
 dist = (float)readData(PUBLIC_ADDR, eDistance) / 10;//Read distance register, one LSB is 0.1mm
 Serial.print("distance = ");
 Serial.print(dist, 1);
 Serial.println("mm");
 
}

[/code]

And the Serial monitor : 

Failed to write coil! Connection timed out
failed to read registers! Connection timed out
distance = 6553.5mm 

Right, this one is that the sample code is not compatible with MEGA.
You can only replace the controller (Leonardo) or modify the code yourself.

Hello, thank you for your response. We have indeed been using the arduino leonardo, with the shield directly on it, and still getting the same error. 

I have the Arduino Leonardo. As previously mentioned, I have gathered all the necessary equipment. Could you please provide a more detailed answer on the matter?

If you get the same situation with Leonardo with the same wire connection. It should be a hardware failure of this URM14, you can seek after-sales service like the merchant you purchased it from.
BTW, is there some slight noise when the URM14 is powered? Usually the probe will make a slight "click" sound.

No, there is no noticeable noise when the device is powered by a 9V source. However, it does become somewhat warm after being used for a short period. This could reinforce the notion that we may have a defective sensor. I have contacted technical support and am currently awaiting a response. I purchased the product directly from the DFRobot website.