Hooking up an Arduino-based sun/wind sensor to an HAI OmniPro II

I'm almost done building a solar radiation and wind sensor using Arduino and now need to figure out how to best connect it to my HAI OmniPro II. I essentially need the HAI to know if it's windy (binary, yes or no, based on a threshold) and sunny (also binary, and separate from the windy reading). With this information, the HAI will send commands to some exterior motorized shades.

What would be the best way to get that info from the Arduino to the HAI? Dry contact interface? Do I need a relay? Somehow treating it as a zone instead? Any ideas?

Thanks in advance...

I'm pretty sure this would generally be done by leaving a zone set to Auxiliary. Auxiliary zones are designed to use open/closed as secure/unsecure, but only for triggering macros and other actions, rather than alarm conditions.

The Worthington Distribution forums would have been a good place to ask, but they were hacked, shut down, and are now only re-opening for dealers/installers. Cocoontech forums could probably answer as well.