| 摘要 |
PROBLEM TO BE SOLVED: To shorten a period for specifying a failure site in a monitoring control system.SOLUTION: A monitoring control system comprises: a duplex control device; a first relay unit connected by a PIO#1 and a PIO#2; and a second relay unit connected by a PIO#3 and a PIO#4. The first relay unit, the second relay unit, and the PIO#1-#4 comprise respectively, a communication LED. When a non-communication period with the control device reaches a period equal to or longer than a regulated value, the first relay unit, the second relay unit, and the PIO#1-#4 turn the communication LEDs off, and when they receive communication data from the control device, they execute a check sum to the communication data, then if a sum check error is not present, they turn the communication LEDs on, and if the sum check error is found, they turn the communication LEDs off.SELECTED DRAWING: Figure 2 |
