SYSTEM FOR CHECKING PLURALITY OF VOLTAGES

摘要

PURPOSE:To make it possible to easily and certainly check voltages corresponding to a plurality of input signals, by a method wherein the comparison result of each input signal and a reference value is held in a hold circuit and taken in by a microcomputer to be discriminated. CONSTITUTION:A microcomputer 6 sets a select signal S to L and supplies the reference value VR from a reference value generating circuit 2 to each comparators 11-1n as a lower limit reference value VRL. When input signals I1-In exceeds the reference value VRL and, for example, the output signal of the comparator 11 is reversed to H, a flip-flop circuit 4 is set and the signal H from an output terminal Q is held. When a definite time is elapsed, output signals of hold circuits 31-3n are taken in to decide whether all signals are H or not and, in the case of N, an alarm is generated while, in the case of Y, the signal S is set to H and the reference value VR is set to an upper limit reference value VRH to judge whether all signals of input ports P1-Pn are L or not.