| 摘要 |
<p>PROBLEM TO BE SOLVED: To omit the transfer of input data between two systems and also to maintain the control of an object with no sudden change of the control data when one of both CPU parts (A and B systems) has a failure and then the faulty system is switched to the other normal system to carry on the control. SOLUTION: Both A and B systems 17 and 18 receive the input signals and the operation signals from a plant equipment system 50 and an operator station 10 respectively and always perform the same control calculations. For instance, the systems 17 and 18 are set in a control state and a standby state respectively. Then the system 17 outputs the control calculation result and the system 18 outputs no control calculation result. When a self-diagnostic means 171 detects the failure of the system 17, the system 17 is switched to a fault state from its control state. Meanwhile, the system 18 is switched to a control state from its standby state. As the systems 17 and 18 are always performing the same control calculations, no transfer of input signals is needed between both systems together with no sudden change of the control data. Thus, the stable control is maintained for a control object.</p> |
