Arduino Leonardo - Uart


I have a question. I am sending data to the serial port:

Serial.println ("TEST");

When the serial monitor is open it is OK, but if it is turned off, the data is not sent.
How to make them send continuously?

I want to send them to the ESP8266 module

How do you have the ESP connected to the Arduino?

This is normal behaviour for a 32U4 based system.

Serial.print does not print on the serial port; it prints on the USB port which is a different animal in case of a 32U4 based board; on the PC it's seen as a serial port though. To print to the serial port (pins 0 and 1), you need to use Serial1. And that will not flash the leds.

ESP is connected to RX and TX.

Thank you very much. Of course, you were right. It works.

I have one more problem.

If programming through IDE Arduino, everything is fine.

If the same program compiles in Visual Studio Code on the platform, the RX LED is still lit.
Even if it's an empty program.

Has anyone encountered such a problem?