If you want an independent low power 12v rain monitor with switched output for the dome controller take a look at the Hydreon RG-11. I have one as a belt-and-braces backup for the AAG. The RG-11‘s switched output is wired in parallel to the AAG so either unit will cause Pulsar’s Rigel controller to close the shutter.
The RG-11 uses IR to detect rain droplets on a transparent dome, same as automatic windscreen wiper control in cars. It does have an internal heater to help evaporate condensation and works in a different way to a capacitive or resistive water sensor by reacting to sudden changes in reflected IR on the clear dome to trigger the relay so even if static water droplets are on the dome as long as no further droplets are seen then it will open the relay much earlier than the AAG unit.
My experience so far is that cloud detection is more important than direct water droplet monitoring to prevent the optical equipment from rain damage since the sensing area of capacitive/resistive/optical rain sensors is rather small, the telescope can get quite wet before a single droplet is detected by rain detectors, I consider these to be fall-back safety backup devices rather than a primary controller.
I have mixed feelings about ACP as the observatory control software and was using CCD Commander for a while. Having a Paramount I am tied to having the TheSkyX running and ACP won’t work directly with TheSkyX’s automation interface. ACP requires Maxim and Focusmax so I have four separate applications running that often require updates to adapt to changes to Windows OS.
The only function in ACP that made it attractive was the scheduler engine. With our UK weather, being able to ask ACP to image a target automatically and keep acquiring data at the best times, however many nights / weeks / months that might need until all requested data had been captured, was the ‘killer’ application.
Software Bisque have been dropping hints that they are developing a new version of Orchestrate for TheSkyX that would offer many of ACP’s fuctions for the last four years or so but so far no news of progress or a release date and I couldn’t wait any longer so am committed to ACP, Maxim and Focusmax for some time to come. Certainly keeps you poor this hobby!