Multiple sensor gas or fire detector system - employing microprocessor which tests condition of each sensor in turn

摘要

All the sensors or detectors (15/I...15/XV) are connected in parallel across one common cable (20,29,37). Each sensor has a window detector, digital comparator, or other method for identifying an incoming command addressed to it. Commands for other sensors are ignored. The control unit comprises an interface unit (14) which connects the sensors with the microprocessor (12) and with an output unit (13). A power supply (11) serves the control unit and also provides power, via a transformer (38), to the sensors. When a sensor receives a command from the processor its measuring circuits are switched on. The results of the measurement are then transmitted to the processor. Output (13) controlled by the processor is typically to an alarm unit (19), hard copy printer (18), VDU (17) and memory (16). The connecting cable may use some fibre optic cores.