I have my system control my garage. I have a motion sensor in the garage, an IR beam sensor across the garage openings, garage magnet contacts on the garage doors, and relays so I can control the garage. I also have an electronic deadbolt on the door leading to the garage, and of course magnetic contacts on that door and a door leading outside from the garage. I also have a keypad that picks up RFID fobs at the door leading inside.
It may seem like overkill, but over the years we have appreciated it. My OMNI PRO II controls it all.
For the alarm to trigger, both a garage door needs to be open AND the beam needs to be broken. I did this to avoid false alarms should a garage door ever open by mistake (it happened to a neighbor) and to give me a bit more time, if I want to pull into the driveway, open the door, but NOT enter for a bit (like to get the mail.)
The motion sensor and beam and door sensors all detect motion, control the light, and eventually close the garage doors should no activity occur for some time.
The electronic deadbolt is very handy. When the garage doors are closed and the alarm off, the deadbolt unlocks the door leading to the garage for unrestricted access. After a garage door is open for a minute or two, the deadbolt locks, so if someone enters the garage, they can't just get in the house. My system also announces "garage" should the beam be crossed. I enter my code to unlock the deadbolt if I have to get in. Also, the deadbolt unlocks automatically for a minute when we arrive home and deactivate the alarm with our keyfob. And any fire alarm would automatically unlock all doors.
One last thing. I did add an exit button inside the house to get into the garage. If the deadbolt is locked, I can just push this button to unlock the door should it be locked, in case of fire or an emergency, and it has a battery backup. This was important for safety detail. The button it large and says EXIT on it and lights up so anyone can figure it out.
We like the system because it is very user friendly, but still very secure.