| 摘要 |
PURPOSE:To enable switching between control systems without using any complicated circuit by comparing the level of each control output with the output of a self-diagnosis part that delivers signals of different levels in response to the normal or abnormal state of each control system and performing the switch between those control systems in terms of a logic circuit. CONSTITUTION:The output of a self-diagnosis part 13 is set at a high level when a control system 10 is normal and therefore a low selector 14 selects the control output given from a D/A converter 12. While the signal of a low level is supplied to a terminal of an AND gate 25 via an inverter 26 and the output of the gate 25 is set at a low level. Thus the signal of a low level is delivered from a low selector 24. While a high selector 30 selects the control output given from the selector 14. When both control systems 20 and 10 are normal and abnormal respectively, the output of the part 13 is set at a low level together with the output of a self-diagnosis part 23 set at a high level respectively. Then the outputs of the selector 14 and the ate 25 are set at high levels. Thus the control output given from a D/A converter 22 is delivered via both selectors 24 and 30.
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