I tried posting earlier but it didn't go through for some reason.

I was setting up linux with serial mux and audio loopback to use with fldigi but the hamlib file for the TS-480 wouldn't PTT the Sun.

I built flrig and that worked, so if you have issues trying to get fldigi with hamlib to work, the PTT seems to be broken but the TS-480HX in flrig, sends PTT properly.

The overall recipe is tty0tty kernel module loaded for the CAT traffic to pass through.

I use Alsa with the loopback module loaded for the VAC audio.

The only hitch was glitching in the audio when running 48000 sample rate at 64 buffer, so running the buffer up to 1024 fixed it.

The soundcard I'm running is a Focusrite Scarlett 8i6 3rd gen.

If you want to skip flrig entirely, I found out that the rig-cat file for TS480 does work properly.

You might want to have a look at github.com/ftl/tciadapter. This allows fldigi to communicate with ExpertSDR without the need for building the tty0tty kernel module. The tciadapter can run as a service.

73, Florian