I am struggling to know how to interface the commercial smoke detectors used in fire alarm.I am not able to understand the logic of interfacing these detectors. I have one from system sensor model no-2351E named SMOKE DETECTOR-PHOTO. I am not able to find datasheet of this model but found some wiring diagram on google. But I am not able to understand those wiring diagrams do they work on digital NO/NC or analog? Actually I am building fire alarm system for home but got stuck on how to interface these sensors with microcontroller... Any help would be appreciated.
One or multiple detectors are connected in parallel to a party line, supplied by 12 to 24 V DC through a 470 resistor. If a detector trips, it shorts the line (latched), causing a high voltage drop at the resistor. Opening the loop resets the latch.