Hi guys
In Australia these Siemens Zone Controller dealies are very commonplace. The model I had was SEM 12116 - a 6 zone version. Basically the system supports "EXTRA" panels. So i reverse engineered the protocol to let an ESP32 flashed with ESPHOME become the EXTRA panel by injecting frames on the bus and also listening to get the status.
Ive put it onto my github repo:
Hope this is useful to others. I also integrated the Samsung HVAC bus component onto the same ESP32 so that I have a single component on HA to control my AC ducted system with zones!
Regards
Gus