CURRENT LOOP POSITIVE/NEGATIVE LOGIC RECOGNITION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a current loop positive/negative logic recognition circuit easy in the setting change of a positive logic or a negative logic without setting the positive logic or the negative logic on a receiving side when communication is performed in a current loop. SOLUTION: A photocoupler 3 converts the input of a positive/negative logic setting signal from a positive/negative logic setting switch 4 on a peripheral device side into a receiving side logical level. A photocoupler 5 converts an input signal from a signal transmission switch 6 on the peripheral device side into a receiving side logical level. And, an EXOR circuit 7 takes an exclusive-OR of a signal obtained by the two photocouplers 3 and 5 and outputs it.