USB to serial adapters on WSL

Windows Subsystem for Linux supports USB-serial devices. The device must be recognized in Windows Device Manager first. If Windows doesn’t recognize the device, perhaps try the device on a native Linux PC.

Configure USB-serial adapters in WSL by adding the WSL username to “dialout” group:

adduser $(whoami) dialout

Plug USB-serial adapter into the PC. Look in Windows Device Manager under Ports to see the COM port number. See troubleshooting notes below if it doesn’t show there.

The device must show in Windows Device Manager → USB Devices → Ports. If so, try in WSL terminal, (assuming device is on COM 5 for this example):

chmod 666 /dev/ttyS5

The serial device baud rate must be consistent between device and PC. If the baud rate is incorrect, either no text or garbled text will be seen. For example using 115200 baud:

stty -F /dev/ttyS5 115200

Connect to serial devices using PuTTY with WSL or using command line like

screen /dev/ttyS5 115200

Note:

• COM port number can change upon plugging in the same device, especially if replugging into a different physical USB port on the PC.
• If plugging in a different unit of the same type of device, it may likely also get a new COM port number (e.g. two Red Pitayas, even if sequentially plugged into the same USB port, may well get different COM port numbers).

Troubleshooting:

If the device doesn’t show up in Device Manager → Ports, see if it was mistakenly enabled as a Mouse or Human Interface Device. If so, unplug and replug your device.

If it still fails to show up as a Port, instead showing up as mouse or HID, try right-clicking and Disabling the device and unplug/plug it once more.

If it still fails, maybe the Windows device driver is missing. Try the device in a native Linux PC and see if the device works there.