I have multiple Honeywell prestige (9321) thermostats in my home (each running a different zone). Do these thermostats communicate using the Enviracom bus, or is that something that Honeywell no longer uses. It looks like some of the older VisionPro stats use the EnviraCom bus, but I don't see any mention of it in the newer documentation.

I'd like to interface with the thermostat via RS232 to control setpoints through my home automation system. There's an EnviraCom module that allows RS232 communication coming into the EnviraCom bus that allows you to control the thermostats on the bus (http://www.amazon.com/Honeywell-W873.../dp/B00097BEF4). The only issue that I'm having is that I haven't been able to determine if the Prestige stats use the EnviraCom bus or not...

Thanks!