| 摘要 |
PROBLEM TO BE SOLVED: To prevent the sudden switching variance by monitoring one of two signals in an arithmetic cycle preceding by one step and switching the signal to the other one when the monitoring result of the former signal is abnormal and the monitoring difference of the latter signal is kept within the prescribed value against the former signal. SOLUTION: The output of both instrumentation transmitters 1 and 2 are sent to a switching circuit 5a via a subtracter 7, a delay element 8 and then an elevating monitor 9. Then the difference between both signals X and Y is outputted from the subtracter 7 and sent to the monitor 9 after the delay of an arithmetic cycle L undergone via the element 8. The monitor 9 checks whether the output of the subtracter 7 is kept within the prescribed valueΔor not. If kept within the valueΔ, a switch command signal 5s is sent to a switch 6 when a switch enabling signal 9s is received and also an abnormal detection signal is received from an elevating monitor 3 (4). Based on the signal 5s, the input is outputted to the signal Y, for example, with switching. Therefore, the switched signal Y is changed into a signal having its change kept within the valueΔagainst the preceding signal X. Then the sudden signal change can be prevented.
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