This is a complicated question. Are you referring to ACP Expert or ACP without the Scheduler? ACP without the scheduler does not do "restarts". With the Scheduler it does but it needs to be able to open and close the shutter for things other than weather. It's OK (and good!) that you have a hardware shutter control. Either way some provision needs to be made to get that safe/unsafe signal into ACP. Also ACP does dome azimuth control, and it needs to know when the dome has finished rotating so it can know when to start exposing again. The design of ACP is to use the universal ASCOM dome interface to control the rotation and shutter, and this provides the Scheduler the route to open and close the shutter for reasons unrelated to weather safety (flats, evening startup, morning shutdown). I know nothing about HitecWeatherDeluxe. Does it have any sort of API interface or how could a separate program determine whether the weather is safe or not?