| 摘要 |
PURPOSE:To check a process control easily, by changing over a changeover switch to a checking side, and outputting a process control signal which has been stored at the checking start time point, in case when a checking start signal is provided and a variation of a process signal is below a prescribed value. CONSTITUTION:When a start signal TST os checking start is not inputted, changeover switches 4-1-4-3 are located as shown in the figure, a controller CT1 to be checked inputs a process signal PCI through a circuit 2, provides a control signal 1a to process device through the changeover switch 4-3, and also stores it in a memory circuit 6. At the checking time when the signal TST is inputted, if a variation of the signal PCI is below prescribed value and a process control system is stable, the circuit 2 outputs a signal 2a, and sets the changeover switches 4-1- 4-3 to the reverse position to that which is shown in the figure, by a signal 3a from a switching circuit 3. In this way, a signal 5a from a checking signal generator 5 is inputted to CT1, and the circuit 6 outputs a signal 6a consisting of the signal 1a. When the signal PCI is varied, the signal 2a is not outputted, checking of CT1 is suspended, and CT1 executes a regular operation. |
