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Frequently Asked Questions (FAQ)

Failed to Open Serial Port Device​

If you encounter the error Error: Permission denied, cannot open /dev/ttyUSB0 when trying to open the serial port!

You can troubleshoot the issue by following these steps:

  1. Check if the serial device is properly connected to the PC

  2. Check serial device permissions

For Linux systems, if the serial device has insufficient permissions, you need to run the following commands in the terminal to grant the current user access to the device.

  • View serial device information

Using /dev/ttyUSB0 as an example:

Linux$
ls -l /dev/ttyUSB0

If the device exists on the system, you will see output similar to:

crw-rw---- 1 root dialout 188, 0 Sep 10 21:24 /dev/ttyUSB0
  • Add current user to the dialout group
Linux$
sudo usermod -a -G dialout $USER
  • Log in again
Linux$
newgrp dialout
  1. Check if the serial device is being used by another program