PIR Wiring - Old ADT Safewatch Plus and Detection Systems Hardwired PIR
I'm trying to talk my father through replacing a fried PIR in his system, but it's been super frustrating given that it seems everything he has is non-standard with almost zero documentation on the web. (or at least what I consider to be standard). So he's got an old ADT Safewatch Plus system, and the sensor in question is a Detection Systems DS920Z.
Now here's the wiring on the motion sensor. It only has 4 terminals. +,-,A,T. A and T are wired together. I'm used to a contact closure for A (i.e. 2 terminals), and a separate one for T. So this must be some sort of open collector do-dad or something? To complicate things his "new" PIR is something he found at a garage sale or something, but it at least has standard pinout (+/-, A1, A2, T1, T2). I tell him to connect + to the red wire, - to the black wire, A1 to the yellow wire, and jumper from A2 to - just to see what happens.
Great, the sensor comes on and seems to function properly. Even better, it communicates back to the panel. Only problem is the logic is completely reversed. The zone turns OFF when the sensor sees motion and ON when it does not.
Huh? Is this Detection Systems PIR actually normally OPEN? I didn't know they even made them that way.
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