Hello,
I’ve got a Crestron DIN switching device and would like to interface Openhab with it. Does anyone knows what protocol it uses and if it could be implemented ?
See their protocol here, under Cresnet® Communication
And more details here
What you have is actually a slave, i.e., it does not have any logic but follows the commands from the master (DIN-AP2).
Looking at the specs, there should be 8 relays there, which can be driven by a microcontroller of your choice. Lucky enough, an ESP8266 has 8 available GPIOs 
Thanks, that’s exactly what I tought of, putting an esp inside and job is done 