| 摘要 |
PURPOSE:To switch a defective process controller automatically to a backup unit by detecting a process controller to be used as the backup unit on the basis of a backup designating signal. CONSTITUTION:Detecting the trouble of a process controller 4, a state monitoring device 31 outputs a backup designating signal B to a constitution control device 32. The control device 32 searches a controller 4 waiting as a backup and makes a transmission control device 34 load a program image or data image F of a function of the failed controller to the searched controller 4. Then, the control device 32 designates to start the backup controller 4 and resets a constitutional state memory 33 to a new state. Thus, backup switching can be automatically executed at the trouble of a process controller.
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