DSC PIR Sensor Wiring

Hardware
1

I am interested in using the PIR Sensors i already have in my home. I have configured PIR Sensors with arduino in the past but they only had 3 cables. The DSC PIR Sensor has 4 cables Red, Black, White, & Green. I know Red is 12v, Black is Ground, White is NC/Normally Closed and Green is common. However i dont know how to hook this up with arduiono. I will not power the unit with the arduino i will use the existing power source however i dont know how to wire the white and green wires. How does it work? If there is no motion a signal is sent on one wire and if there is motion a signal is sent on other wire?

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2

The best way to do this would be to use a reed relay or optocoupler in parallel with the white & green wires. Then use the output of that device to supply signal to your Arduino. That will keep the Arduino circuit completely isolated from the alarm panel and not load down the PIR sensor output, nor create any ground loops.

3

Hi Jeff

The alarm contacts (normally closed and common) are relay contacts, when no motion is detected they are shorted, when motion is detected they open.