RX TX 2 Arduino Nano

Hello, can someone explain why, if i send from Arduino 1 to Arduino 2 with RXTX for example 5 i Receive just 83 an it gets lower and lower everytime sometimes it goes up and the Variable is Not stable... ??

example 5?

What is example 5?

Nano 1 sends:

int incomingByte = 5;

void setup()

{

Serial.begin(9600);
Serial.println("SEND–> ");
Serial.println(incomingByte);
Serial.write(incomingByte);
delay(500);
Serial.flush();
}

Nano 2 receives:

int incomingByte = 0; // for incoming serial data

void setup()
{
Serial.begin(9600);
}

void loop()
{
if (Serial.available() > 0) {
Serial.print("RECIVE<-- ");
incomingByte = Serial.read();
Serial.print("I received: ");
Serial.println(incomingByte, DEC);
delay(1000);
}

Serial.println("SEND--> ");
Serial.println(incomingByte);   
Serial.write(incomingByte);

You are sending more than one byte.
You do understand that, right?

decimal 83 = S

conversation from binary to DEC?
I can Not say send Parameter 5 and the Receiver Receives Parameter 5.

I want to use It later to Receive the UID from RC522 RFID from Arduino 1 and Transmit the key of the Card for example UID: 5F 3A C2 E1 to Arduino 2 that already is connected to a SIM800l and Sends Data to a Database .. both Arduinos work Fine but i can Not use one Arduino with rc522 and SIM800L Module because there Are no more free pins left for both Moduls on one Arduino.

Have a look at the examples in Serial Input Basics - simple reliable ways to receive data.

…R

Thank you, that was a great Help!!