Arduino Uno connecting to Arduino Uno via UART?

Question

Arduino

Hello.
I want to set up data transfer between two Arduino Uno via UART. The firmware is working. The payment is stitched. The problem is that when the Arduino is powered off and back on, data transfer does not start automatically. What is the problem? Thanks in advance!
Program code:

void setup(){
Serial.begin(9600);
}
void loop(){
Serial.write(45); // send byte with value 45
delay(100);
}
Here is the wiring diagram:

Answer 1

Tx must be connected to Rx, and Rx to Tx. This is how I see myself in a crystal ball.