Verifying USB to serial adapter working

I need a serial RS232 interface from my computer running Fedora 35 and bought USB to RS232 DB9 adapter from Digitech Computer. I’m not sure how to verify whether this adapter actually works (the box I’m connecting to via serial doesn’t seem to see this interface so I want to be comfortable that the adapter is ok from Fedora end before going any further).

dmesg shows the following: the new adapter is pl2303 from Prolific Technology Inc.

lsusb shows the following

ls /dev/ttyUSB* shows the following (USB1 is the new adapter)

I haven’t installed any drivers for this new adapter as I’m not sure I have to and if I have the documentation didn’t state anything.

Can you tell based on these screenshots that this adapter is working?

It looks like the kernel picked up the adapter and assigned devices to it, so you should be able to use a software serial console to communicate via those devices (/dev/ttyUSB{0,1}). Minicom works well for these purposes, but you may need to run it as root, especially from within a toolbox or other container.

In general, in Linux, if you see a corresponding /dev/* entry to your device, the kernel has “seen” it and has at the very least applied a generic driver to it. You can validate this by executing # lspci -v to see the module line (note the prompt, you’ll need root to see the loaded modules).

If you’re curious as to what level of support the kernel module is providing, you can generally do a web search for the module name and your current kernel version (uname -r) to see the changelog/release notes in the results.

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As Brian says, looks like this is working. A little additional info…

Note the ls /dev/ttyU* output, which shows group rw for groupdialout[1]. That means if you add your user account to that group (and log out and in again) you’ll be able to access this device as non-root. You should also be able to mount the device into a container, although you’ll need to be aware of SELinux configuration in doing that (since the default security policy doesn’t let containers mess with devices like this).


  1. By the way @tfmeier — it’s a lot more useful to us if you can provide text copy-pasted from the terminal rather than screenshots. The screenshots can be hard to read, and if it’s helpful for us to search for specific text to help you, or as in this case, repeat it. ↩︎

Just curious, but wouldn’t being a part of wheel also give you access to the dialout group?

@jakfrost note, non-root alias without sudo (wheel).

Ah yes I see.