| 摘要 |
PURPOSE:To enable a sensor receiving circuit to be diagnosed by providing a function for turning on and off a power supply for a sensor. CONSTITUTION:In a diagnosis, a control circuit 3 renders a relay RL1 inoperative and turns off a power source to a sensor circuit 1. Thus, a transistor TR7 is turned off, an 'H' level is inputted to a receiver circuit 9 and then the circuit 3 operates the relay RL1 to supply the power source to the circuit 1. Sensors 5 have normal-close structures. The transistor TR7 is turned on through an inverter 6 and an 'L' level is applied to the circuit 9. Thus, the circuit 3 checks the operation of a receiving circuit 2.
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