MAINTENANCE SWITCH METHOD/DEVICE FOR PLANT CONTROL INPUT DEVICE, MAINTENANCE SWITCH METHOD/DEVICE FOR PLANT CONTROL OUTPUT DEVICE AND MAINTENANCE SWITCH METHOD/ DEVICE FOR PLANT CONTROL INPUT/OUTPUT DEVICE

摘要

PROBLEM TO BE SOLVED: To easily and safely switch input circuits and output circuits while a plant is driven. SOLUTION: For maintaining one of the output circuits 5a-5n in an output unit 31, one preliminary output circuit 50 is set and a necessary signal is inputted to a maintenance setting unit 12. Then, the preliminary output circuit 50 is started by permitting an arithmetic unit 1 to access it. A circuit being a maintenance object executes a prescribed processing until the preliminary output circuit 50 completes rises. When the preliminary output circuit 50 completely rises, an output control part 41 and a switch circuit 42 switch the circuit being the maintenance object to the preliminary output circuit 50. Thus,. the output circuits 5a-5n can securely be maintained/inspected while the plant is operated.