| 摘要 |
PURPOSE:To back up a system with a small number of controllers by controlling processes with normally used control units of plural controllers and controlling a part of control objects with an auxiliary control unit having the same control function as the normally used control unit if an optional normally used control unit is faulty. CONSTITUTION:A controller 11a has control units 5 and 6, and a controller 11b has control units 6 and 7, and a controller 11c has control units 7 and 5. While all controllers 11a-11c are normal, a controlled system 4 is controlled by the unit 5 of the controller 11a, the unit 6 of the controller 11b, and the unit 7 of the controller 11c. If the unit 5 of the controller 11a is faulty, the unit 5 of the controller 11c is operated immediately, and the control of a part of the controlled system 4 which is executed by the unit 5 of the controller 11a till then is continued without interruption by the unit 5 of the controller 11c. Thus, the system is backed up with a small number of controllers. |
