| 摘要 |
PURPOSE:To attain fault diagnosis even in case of a signal drive by providing a gate circuit giving an output as 'normal' and another output as 'fault' in outputs of two sets of valve fault diagnostic devices when two sets of said devices are faulty or do not execute the fault diagnosis among three sets of a value fault diagnostic devices. CONSTITUTION:When a switch SW2 is turned on for the single drive of a fault disgnostic device 8a, only an OR gate 11d goes to 'H', only an AND gate 10d is effective and only an output of the device 8a among the fault diagnostic devices 8a-8c is outputted from the AND gate 10d and outputs of AND gates 10e, 10f go to 'L' independently of the outputs of the devices 8b, 8c. Further, only the OR gate 11c connected to the switch SW2 among OR gates 11a-11c goes to 'H' and the others go to 'L', and the output of the device 8a is outputted as it is from the OR gate 11a. ON the other hand, the output of the OR gate 11b is always at 'L' and the output of the OR gate 11c is always at 'H'. As a result, the output of the valve fault diagnostic device 8a is obtained as it is from an output M of a majority decision circuit 9.
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