SUPERVISORY EQUIPMENT FOR SIGNAL TRANSMISSION

摘要

PURPOSE:To save time for checking a fault of an isolator by securing such a constitution where the transmission signal can be received as it is via an isolator and the received transmission signal is compared with the transmission signal under transmission for easy detection of the fault of the isolator. CONSTITUTION:The transmission signal produced from a transmitter/receiver main body 1 and extracted out of a transmission output terminal Tx is supplied to a transmission driver part 3 via a photocoupler 2 serving as an isolator and transmitted to the remote side via a transmission line. A fixed period is secured for waiting of return after the transmission signal is received. Then a return signal is transmitted during said return waiting period when the transmission signal is received by the remote side. The return signal is first received by a return signal detecting part 4 and supplied to a photocoupler 6 via a 2- input NOR circuit 5 serving as an OR circuit. The output of the photocoupler 6 is supplied to a reception input terminal Rx of the body 1. While the output of the photocoupler 2 is supplied to the other input terminal of the circuit 5.