I'm using the Visual Studio Code extension to develop for Arduino which works great.

It doesn't have a Serial Plotter like the regular Arduino IDE, which I need to debug this project. I can run the Arduino IDE's Serial Plotter alongside Visual Studio Code without too much of a problem.

However, if I try to compile and upload from Visual Studio Code while the Arduino IDE is running, the port is busy (not a surprise):

avrdude: ser_open(): can't open device "/dev/cu.usbmodem14201": Resource busy
An error occurred while uploading the sketch 

So I have to keep exiting and relaunching the Arduino IDE every time I build.

Anyone have a suggestion for how to work around this? Using an iMac as development environment.

  • 1
    isn't it enough to close Serial Monitor window?
    – Juraj
    Nov 7, 2018 at 7:47
  • this does work, but is still kind of annoying... Thanks! Nov 7, 2018 at 22:08

1 Answer 1


Without very specialized software that can create two new devices with the correct "teeing" policy, it's not going to be possible. Only one program can open a serial port at a time (certainly and have it get anything intelligible out of it...)

I would suggest you may want to add a second serial port. Use an FT232 adaptor to communicate on another serial connection (or a SoftwareSerial connection at a pinch) for your debugging information. You really want a board with more than one serial port for this - or a board with a native USB for programming and a hardware serial port for data communication.

Another alternative is to ditch the serial for programming altogether and program your board through a dedicated programmer, thus leaving your serial port free for data communication.

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