Connect nodemcu esp32 to multiple esp32 via RS485 modules

[mujed]

hello all.

i am trying to connect 2 nodemcu esp32 via rs485 modules but its not working. the esp32 and modules are connected in the following diagram:

the code used is the following:

#include <Arduino.h>
#define RXD2 16
#define TXD2 17
#define CTD2 22
void setup()
{
  // put your setup code here, to run once:
  Serial2.begin(9600, SERIAL_8N1, RXD2, TXD2);
  Serial.begin(115200);
  Serial.println("Begin Software...");
  Serial.println("Serial Txd is on pin: " + String(TX));
  Serial.println("Serial Rxd is on pin: " + String(RX));
  Serial.flush();
  pinMode(CTD2, OUTPUT);
  digitalWrite(CTD2, LOW);
}

void loop()
{
  while (Serial2.available())
  {
    int size = Serial2.available();
    String data = Serial2.readStringUntil('\n');
    Serial.println("RECEIVED: ");
    Serial.println(data);
  }
  if (Serial.available())
  {
    String data = Serial.readString();
    Serial.print("Sending: ");
    Serial.println(data);
    digitalWrite(CTD2, HIGH);
    Serial2.println(data);
    digitalWrite(CTD2, LOW);
  }
}

N.B first i tested this code (without the transmission pin "22") on a normal uart communication without rs485 and it was working fine. what can be the problem?
thanks in advance

[horace]

try using Serial2.flush() to empty the transmit buffer before switching CTD2

  if (Serial.available())
  {
    String data = Serial.readString();
    Serial.print("Sending: ");
    Serial.println(data);
    digitalWrite(CTD2, HIGH);
    Serial2.println(data);
    Serial2.flush();             // <<<<< try
    digitalWrite(CTD2, LOW);
  }