Please help to test my device ( project )

[proasnet]

Dear @emelianov, I had my first project with Modbus RTU. I need only help to test a my hardware, custom board. Programs is only for HW testing, from your examples.
My device project is as a slave. CPU is ESP32 WROOM, with modbus converter MAX3485 with DE.
Some is bad, communication between this CPUs not working.

Slave program

#include <HardwareSerial.h>
//#include <SoftwareSerial.h>
#include <ModbusRTU.h>
#define TXenableRS485 21
#define M_RX 34
#define M_TX 32


HardwareSerial RS485(1);
//EspSoftwareSerial::UART RS485;
ModbusRTU mb;

void setup() {
  Serial.begin( 115200 );
  

//  pinMode( TXenableRS485 , OUTPUT );
//  digitalWrite( TXenableRS485 , LOW );

  RS485.begin( 9600, SERIAL_8N1 , M_RX , M_TX );
  
  //RS485.begin( 9600 , SWSERIAL_8N1 , M_RX , M_TX , false );

  mb.begin( &RS485 , TXenableRS485 );
  mb.setBaudrate( 9600 );
  mb.slave( 1 );

  // RTU SERVER
  mb.addIreg( 100 ); // analog input
  mb.addIreg( 101 ); // analog input
  mb.addIreg( 102 ); // analog input
  mb.addIreg( 103 ); // analog input
  mb.addIreg( 104 ); // analog input

  // RTU SERVER
  mb.addIsts( 100 ); // digital input
  mb.addIsts( 101 ); // digital input
  mb.addIsts( 102 ); // digital input
  mb.addIsts( 103 ); // digital input
  mb.addIsts( 104 ); // digital input

  // RTU SERVER
  mb.addHreg( 100 ); // holding
  mb.addHreg( 101 ); // holding
  mb.addHreg( 102 ); // holding
  mb.addHreg( 103 ); // holding
  mb.addHreg( 104 ); // holding

  // RTU SERVER
  mb.addCoil( 100 ); // coil
  mb.addCoil( 101 ); // coil
  mb.addCoil( 102 ); // coil
  mb.addCoil( 103 ); // coil
  mb.addCoil( 104 ); // coil
}

void loop() {
  mb.task();                // Server Modbus TCP queries

  mb.Ireg( 100 , 400 ); // analog in
  mb.Ireg( 101 , 401 ); // analog in
  mb.Ireg( 102 , 402 ); // analog in
  mb.Ireg( 103 , 403 ); // analog in
  mb.Ireg( 104 , 404 ); // analog in

  mb.Ists( 100 , true ); // digital input
  mb.Ists( 101 , false ); // digital input
  mb.Ists( 102 , true ); // digital input
  mb.Ists( 103 , false ); // digital input
  mb.Ists( 104 , true ); // digital input

  mb.Hreg( 100 , 511 ); // holding
  mb.Hreg( 101 , 501 ); // holding
  mb.Hreg( 102 , 502 ); // holding
  mb.Hreg( 103 , 503 ); // holding
  mb.Hreg( 104 , 504 ); // holding

  Serial.println ( "coil 0: " + String( mb.Coil( 0 )) + " coil 2: " + String( mb.Coil( 1 )) + " coil 2: " + String( mb.Coil( 2 )) + " coil 3: " + String( mb.Coil( 3 )));

  yield();
}

For testing this my hardware project, I mount a master RTU with the same converter, EPS8266 Wemos D1 mini.
Master program

#include <ModbusRTU.h>

#include <SoftwareSerial.h>

#define SLAVE_ID 1
#define FIRST_REG 100
#define REG_COUNT 5

SoftwareSerial S(7, 5);


ModbusRTU mb;

bool cb(Modbus::ResultCode event, uint16_t transactionId, void* data) { // Callback to monitor errors
  if (event != Modbus::EX_SUCCESS) {
    Serial.print("Request result: 0x");
    Serial.print(event, HEX);
  }
  return true;
}

void setup() {
  Serial.begin(115200);
  S.begin(9600, SWSERIAL_8N1);
  mb.begin(&S);
  mb.master();
}

uint16_t res[REG_COUNT];

void loop() {
  
  if (!mb.slave()) {    // Check if no transaction in progress
    mb.readHreg(SLAVE_ID, FIRST_REG, res, REG_COUNT, cb); // Send Read Hreg from Modbus Server
    while (mb.slave()) { // Check if transaction is active
      mb.task();
      delay(10);
    }
    Serial.println(res[0]);
    Serial.println(res[1]);
    Serial.println(res[2]);
    Serial.println(res[3]);
    Serial.println(res[4]);
  }
  delay(1000);
}

Thank you very much for help.

[Alexander Emelianov]

If both rs-485 converters are the same server also needed to have RE/DE pins control from code.