| 摘要 |
PURPOSE:To realize a highly economical fault detecting method with a high reliability for the digital input device by generating the false digital data by the command given from outside and then sending the digital data to the processor. CONSTITUTION:In case control signal CK1 enters from outside, switch circuit 33 closes and the input terminal of comparator 18 is connected to power source VS via diode 34. And the output of all comparators 18 become 1. In this case, the output is taken into processor 2 via multiplexer MX19 and whether the output is 1 or not is checked to decide the presence or absence of the fault. when the fault is detected, error signal ERROR is generated and held at register 35 to light up luminous element 35. In case control signal CK0 is put in, the output of comparator 18 becomes 0, and whether the output is 0 or not is checked through processor 2. Then both control signal CK1 and CK0 are used together to ensure the assured detection of the fault for the input device. |
