Great Bus to AC device

This has always been the problem with A/C.

Around about 15% of the market (mainly large / commercial) uses 24V ac "RWG" standard, and this is what C-Bus thermostats can do. It all works by throwing relays and the thermostats do all the termperature sensing, run the PID control algorithms and so on.

The rest of the market is totally fragmented. There is no standardisation at all, and most of the systems are either self contained or proprietary, or both. In this case the only way for controlling them is for the maker to provide an interface.

The grand plan at the time of the design of the C-Bus Thermostat is that makers CAN take bus messages to put into a "Plant Controller" which will in turn drive their specific equipment. The bus messages are all there, it's all defined, it's even all published and available for free. What it means is that a new hardware device sits on C-Bus, reads the messages in application $AC, and uses them to drive the plant (ie the heavy equipment) INSTEAD of using a C-Bus Relay unit.

The technology is all there sitting waiting to be exploited - it just needs a few makers or keen users of A/C equipment to develop the interface brick. Don't expect Clipsal to do this, the A/C market is so fragmented, and so varied in world markets, that there would need to be something like 10 or 20 products developed (in an ever changing field) in order to cover something like about another 30% to 40% of the A/C market. (I can see that a clever C-Bus plant control message to Infra-Red blaster might actually be the one really big thing in the whole picture).

But it really needs a bit of pressure brought to bear on your A/C makers - stir them up and demand that they do it. All the information and technical help is sitting there waiting for them to pick it up.