Serial communication - Arduino Mega and ESP32

[beneionut2208]

I have an Arduino Mega and an ESP32 that I want to connect by serial communication. The thing is, pins 0 and 1 for RX/TX from Mega are not available because they are covered by a screen shield. So, I decided to use pins 18 and 19 for RX/TX, but with the classic code it doesn't work. How to define that I use pins 18 and 19 instead of 0 and 1? I mention that when connecting to pins 0 and 1, the communication works. I'll attach the code for both boards.
Arduino Mega:

void setup() {
  Serial.begin(9600);
}
void loop() {
  Serial.println("Hello");
  delay(1000);
}

ESP32:

#define RX 16
#define TX 17
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial2.begin(9600, SERIAL_8N1, RX, TX);
}
void loop() {
    Serial.println("Message Received: ");
    Serial.println(Serial2.readString());
}

[Idahowalker]

Do you know how many hardware serial ports the Arduino MEGA has? Why not use an alternate MEGA hardware serial port?

[runaway_pancake]

@beneionut2208

How to define that I use pins 18 and 19 instead of 0 and 1?

You didn't even attempt a websearch.
I did.
Use Multiple Serial Ports on the Arduino Mega | Arduino Documentation

Mega 2560 Rev3 | Arduino Documentation

Serial1

[Whandall]

You should use a voltage divider for the Mega-TX ESP-RX connection to lower the 5V to 3.3V.

[GolamMostafa]

Caution:
Use level shifter to connect MEGA and ESP32 as --

1. Connect MEGA and ESP32 using UART2 Ports as per Fig-1 using level shifter.

Figure-1:

2. Upload the following sketches:
MEGA Sketch:

//MEGA
void setup() 
{
  Serial.begin(9600);
  Serial2.begin(9600);  //RX2 = 17, TX2 = 16
}
void loop() 
{
  Serial2.println("Hello"); //sending to ESP32
  delay(1000);
}

ESP32 Sketch:

#define RX2 16
#define TX2 17

void setup()
{
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial2.begin(9600, SERIAL_8N1, RX2, TX2);
}

void loop()
{
  byte n = Serial2.available();
  if (n != 0)
  {
    Serial.println("Message Received: ");
    Serial.println(Serial2.readString());
  }
}

[horace]

an aletrnative to a level shifter is a potential divider - see Mega_with_ESP-01

[rahmanfuad]

basically I have problem with the read.String() that cannot read the data transfer from mega 2560 to esp32 through serial communication2. I hope someone can give to me the solution about my problem

[horace]

how have you connected the Mega to the ESP32? remember the Mega uses 5V logic the ESP32 3.3V
upload your code (using code tags </>)