Interfacing between Programming and Arduino

I would like to know what code to write to get my Arduino sketch to 'talk' to a Programming sketch. Does someone know the principles of this communication?

Fabiao

You open a serial port on each side, and use that to communicate between the two.

Do you mean that I should open the serial monitor of the Arduino IDE and the Programming serial monitor simultaneously? This is just to clarify.

Thank you for the reply.

Fabiao

Do you mean that I should open the serial monitor of the Arduino IDE and the Programming serial monitor simultaneously? This is just to clarify.

No. Processing does not have a Serial Monitor. There are examples provided with Processing that show how to communicate with the Arduino. Clearly, you have not looked at them.