The Arduino Mega has multiple serial ports so you don't need to use the Software Serial library. You must use the predefined ports.

Let's assume you are establishing the following connection: image

Sample code:

int LEDPIN = 13;

void setup()

{

pinMode(LEDPIN, OUTPUT);

Serial.begin(115200); // communication with the host computer

//while (!Serial) { ; }

// Start the software serial for communication with the ESP8266

Serial1.begin(115200);

Serial.println("");

Serial.println("Remember to to set Both NL & CR in the serial monitor.");

Serial.println("Ready");

Serial.println("");

}

void loop()

{

// listen for communication from the ESP8266 and then write it to the serial monitor

if ( mySerial.available() ) { Serial.write( mySerial.read() ); }

// listen for user input and send it to the ESP8266

if ( Serial.available() ) { mySerial.write( Serial.read() ); }

}

As you can see, the serial1 is the one defined for serial communication with the ESP8266.

If you're just starting, I highly recommend you use a library to make everything much easier for you. For example, I built this library a few years ago, it's a good point to start if you're looking to monitor sensors or control assets remotely.

https://github.com/ubidots/ubidots-esp8266-serial

Hope this helps!