| 摘要 |
PROBLEM TO BE SOLVED: To provide a relay control system and a communication relay method capable of preventing degrading of communication performance between an arithmetic part and input/output parts even when the number of input/output parts increases such as a large scale plant.SOLUTION: The relay control system includes: plural input/output devices for inputting/outputting a data including a request or a response accompanying an instruction to control objects; an arithmetic unit that instructs to control the input/output device; and plural relay units each of which relays a communication between the arithmetic unit and the input/output device. Each of the relay units connects plural input/output devices and a relay unit via ring-like communication circuit. Each of the relay units has communication possibility determination means that determines whether the data should be relayed, and based on the determination result of the communication possibility determination means, relays the communication of the data. |
