A device for detection and alarm

摘要

The detection device comprises a central alarm (1) communicating with the detectors (7a, 7b) by means of two wires of rows (l1 and l2). Information for the addressing and synchronization signals are emitted by the central unit by making the inversions of peeling of the voltage of the threads of line l1 and l2 (). The detectors respond to the central unit by an increase of the current consumed (it). A detector detects the address supplied by the central and returns of the variations in current, which are synchronized with the synchronization signals.