MONITOR AND CONTROL SYSTEM

摘要

PURPOSE:To prevent malfunction of a device to be controlled by providing a monitor circuit monitoring the operation of a microprocessor and turning off a device control (CONT) output relay and a device selection (POS) output relay in order when abnormality is detected. CONSTITUTION:A watchdog timer 19 monitors an output outputted at each prescribed time from a microprocessor (muP)11 and if the muP11 is stopped because of abnormality or the like and the said output is not received even though a prescribed time is elapsed, an output R1 is outputted to reset a CONT output register 14. A timer 20 outputs an otput R2 after the output R1 is received from the timer 19 after a prescribed time (after the CONT output register 14 is reset until a CONT relay 18 is turned off completely) to reset a POS output register 13. A data ''0'' is written in the CONT output register 14 at normal time to turn off a CONT output relay 16 so as to turn off the device to be controlled. Then, the data ''0'' is written in the POS output register 13 so as to turn the POS output relay 17.