The next step I'm going to take this is to have HS send me a text message and email to let me know when both cars have been out of the garage for over 10 minutes and the door is still open. I'll then be able to trigger an event via text message or email (I can send email from my phone via a text message) that will close the door and email me again to confirm it's happened. I can handle that part, it's just the CAC that confuses me. Maybe a separate tutorial should be written just on DM CAC?
I'm using one of those nice Garage door contact sensors (In conjunction with my SECU16/Ocelot) that I ordered from Martin to handle detecting the garage doors status.
By code, you shouldn't be able to close the door without having line of sight to it. (A camera is of course acceptable). That said, if you're going to do so, then you should consider an announcement when closing the door(s) to warn anyone in the way... just in case.