I'm an HVAC guy that works with Crestron controlled systems. I was wondering how the remote 2 wire sensors like CHV RTHS communicate with a CHV thermostat. All the other manufacturer brands typically have 4 wires. 2 wires for power and 2 for data.

I am accustomed to remote temperature sensors (not humidity)that use 2 wires but that is simple RTD circuit.

I can't find any details in Crestron install manuals or their web site. Hoping someone can enlighten me.

Thanks,