Hmm.. correct me if I'm wrong but I think the Flat S IOs are connected via some USB board internall? And it appears that when using just DietPi, I don't get any USB port to work (even inserting the Modbus External USB dongle I had to the regular Rapsberry Pi) so therefore also the internal RS485 ...

I've been running Loxberry ( https://wiki.loxberry.de/installation_von_loxberry/die_installation_von_loxberry/start ) for a while on a regular Raspberry Pi 4, with a separate Modbus USB stick and a 24V to 5V stepdown regulator (to provide the Raspberry Pi with 5V power). However, when I stumbled ...