| 摘要 |
<p>PURPOSE:To improve the safety with an instrumentation control system by providing a check function to a control output holding part set in a field to check the operating output signal which is actually delivered to an operating unit. CONSTITUTION:This instrumentation control system contains an arithmetic processing part 1, a control output holding part 2 and a detector 7 and controls the drive of an operating unit 8. The holding part 2 is provided with a holding means 3, an output quantity converting means 4, a comparison means 5 and an output quantity adverse converting means 6. The part 1 performs a prescribed operation based on the measurement input signal PV and the set value SV sent from the detector 7 and sends a control signal MV1 to the part 2. The signal MV1 is held by the means 3 and the unit 8 is controlled via the means 4. The output MV of the means 4 is compared with the holding value of the means 5 via the means 6. Thus no coincidence is obtained between both values if the abnormality occurs. In such a way, the abnormality of the system is detected.</p> |
