Light barrier e.g. forked light barrier, error or failure detecting method, involves connecting microprocessors with transmitters and receivers, verifying function of transmitters and receivers, and detecting light reflected by cam switch

摘要

The method involves arranging a transmitter (17) and a receiver (21) on a side of a distance to be monitored and another transmitter (19) and a receiver (23) on another side of the distance by using two microprocessors (29, 31). The microprocessors are connected with the transmitters and the receivers, and a function of the transmitters and the receivers are verified. Light reflected by a plunged cam switch (25) is detected during discontinuous optical path length, where the microprocessors control the transmitters.