USB-serial adapters on Windows / WSL

Windows natively or with Windows Subsystem for Linux supports USB-serial devices. The device must be recognized in Windows Device Manager.

Plug the USB-serial adapter into the Windows 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.

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.

Connect to serial devices using PuTTY or use WSL.

Windows Subsystem for Linux USB-serial

Command line screen or PuTTY can be used in WSL.

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

adduser $(whoami) dialout

If so, try in WSL terminal, (assuming device is on COM 5 for this example):

chmod 666 /dev/ttyS5

The usbipd program can help debug and connect devices in Windows and WSL.

Troubleshooting

The 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. Distinct devices of the same model, even if sequentially plugged into the same USB port may get different COM port numbers.

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.