ESP32 with water level sensor RS485

Official Hardware Nano Family Nano ESP32
1

I have a circuit with ESP32 and max485 and a water level sensor E RS485. I cant read the date of the sensor and i got the erros RS485 "E0" (address incorrect). Thas is my problem i dont know the address of my sensor, so , i put the code to run with all tre address 0xXX possible , but it didnt find out. Could somebody help me.

//https://www.crescerengenharia.com/post/pta8d08-sensores-pt100-arduino-esp32-clps

#include <ModbusMaster.h>

#define MAX485_dir  4
#define MODBUS_RX_PIN 16 // Rx pin  
#define MODBUS_TX_PIN 17 // Tx pin 
#define MODBUS_SERIAL_BAUD 9600 // Baud rate for esp32 and max485 communication

uint8_t MODBUS_slave_Address = 0x00;
uint16_t MODBUS_slave_RegistersAddress = 0x0001;

ModbusMaster node;

void preTransmission() {
  digitalWrite(MAX485_dir, 1);
}
void postTransmission() {
  digitalWrite(MAX485_dir, 0);
}

void setup() {
  pinMode(MAX485_dir, OUTPUT);
  pinMode(2,OUTPUT);
  digitalWrite(2,HIGH);
  delay(2000);
  digitalWrite(2,LOW);

  digitalWrite(MAX485_dir, 0);


  Serial.begin(115200);
  Serial2.begin(MODBUS_SERIAL_BAUD, SERIAL_8E1, MODBUS_RX_PIN, MODBUS_TX_PIN);

  node.begin(MODBUS_slave_Address, Serial2);

  node.preTransmission(preTransmission);
  node.postTransmission(postTransmission);
}

void loop() {
  uint8_t result = node.readHoldingRegisters(MODBUS_slave_RegistersAddress, 1);
  Serial.println("Data Requested");

  if (result == node.ku8MBSuccess) {
    Serial.print("Nível: ");
    Serial.println(float(node.getResponseBuffer(0) / 10.00F ));
    digitalWrite(2,HIGH);
     Serial.print("MODBUS_slave_Address = ");
     Serial.println(MODBUS_slave_Address, HEX);

  Serial.print("MODBUS_slave_RegistersAddress = ");
  Serial.println(MODBUS_slave_RegistersAddress, HEX);
    return;

  }else{

    Serial.println("comunicação falhou");
     Serial.println(result, HEX);
  }

  Serial.println("");
  delay(1000);

   MODBUS_slave_Address = MODBUS_slave_Address + 0x01;

 // MODBUS_slave_RegistersAddress = MODBUS_slave_RegistersAddress + 0x0001;

 // if(MODBUS_slave_RegistersAddress==0xFFFF){

  

 // }

  Serial.print("MODBUS_slave_Address = ");
  Serial.println(MODBUS_slave_Address, HEX);

  Serial.print("MODBUS_slave_RegistersAddress = ");
  Serial.println(MODBUS_slave_RegistersAddress, HEX);

    node.begin(MODBUS_slave_Address, Serial2);
    node.preTransmission(preTransmission);
    node.postTransmission(postTransmission);
2

That is probably correct. If you send a message with the broadcast address (0), the slave will reply with it's own address. So I think you can ignore the 0xE0 error. If the slave does not respond at all. you would get 0xE2.

You can get the address from the response using getResponseBuffer(0)