TwoArduino boards connected at the same time

If you connect an Arduino board via USB to your PC a virtual COM port will be created. Actually, you can up to 99 such COM ports. So it is no problem to connect more than one Arduino to your PC at the same time. You can select the board you want to communicate with by choosing the desired board in the Tools -> SerialPort Menu.

For each board you can open an IDE window. But keep in mind: if you select another COM port this goes for all the windows. So, take care before uploading sketches not to overwrite programs in the wrong board. The same goes for the serial terminal window. It might help to use a simple terminal program like HTerm to read the Serial.println. But never use two programs to communicate with the same board at the same time; most probably you will have to reboot your PC because you have no more access to that COM port.

Well, you can start a second Arduino task which uses separate resources. And you can select a different COM port with the second task. But still: both applications look alike, and you might easily get mixed when uploading your code.

You might - for some reason - keep different Arduino IDE versions on your hard drive. Whenever you switch between them you most probably have to use the Board Manager to select/install the proper Boards Manager JSON file every time you switch.

contact: nji(at)