Arduino Uno & ESP32 communication using RS485 I am trying to establish a communication between Arduino Uno ( Master) and ESP32 (Slave) using RS485 protocol (using MAX485 module).
I have successfully done this between two Arduino Unos. SoftwareSerial library is what i am using between two Arduino Unos, now trying with ESP32 and Arduino Uno (using MAX485 module)
.
For ESP32 i have used SoftwareSerial (https://github.com/akshaybaweja/SoftwareSerial) library.

After reading the library and making connection i am not be able to establish a communication between them. Sharing my code below.

Receiver

#include &lt;SoftwareSerial.h&gt;

SoftwareSerial softwareSerial(9, 10);
String str;

void setup()
{

  Serial.begin(9600);
  softwareSerial.begin(9600);

}

void loop()
{

  while (softwareSerial.available() &gt; 0) {

    char inChar = softwareSerial.read();

    if (inChar == '$') {

        str.trim();
        Serial.println("received command" + str);
        memset(&amp;str, 0, sizeof(str));
        Serial.flush();
        softwareSerial.flush();
    }
    else {
        str = str + inChar;
    }

 }

}


Sender

#include &lt;SoftwareSerial.h&gt;

SoftwareSerial swSer1(22, 23, false, 256);
String str;

void setup() {

  Serial.begin(9600);
  swSer1.begin(9600);

}

void loop() {

  String sendCmd = "MSG1$";
  Serial.println("Sending ");
  Serial.println(sendCmd );
  char copy[50];
  sendCmd.toCharArray(copy, 50);
  swSer1.write(sendCmd);
  delay(1000);


}


Here my question is where i am going wrong in this project. Please guide me.

Note : DE AND RE PINS are connected to high for sender device and to low for receiver device as given in the RS485 documentation.
Maybe you have already solved this but in any case, have you tried working with the hardware serial ports? You have three of them in the ESP32. I read sowhere else that there may be some interrupt issues using the SoftwareSerial library on the ESP devices, especially at higher baud rates.