Device, system, and method for controlling state quantities in plants

A system comprising:

• a plurality of controllers that transmit an I/O output request that is a request including an operational output for an I/O output device to operate a plant;
• a processor that receives the I/O output request through a network;
• the processor that performs filtering in which an I/O output request from a proper controller out of the received I/O output requests is selected and output;
• the processor that detects an abnormality of the I/O output request;
• and
• the processor that transmits, when the abnormality is detected, an alternate I/O output request, which is a request including an alternate operational output, to an I/O output device corresponding to the I/O output request, and that outputs, when the abnormality is not detected, the I/O output request output from the processor to an I/O output device corresponding to the I/O output request, wherein
• the processor performs the filtering for each of control-unit group including the controllers that transmit the I/O output requests to an identical I/O output device,
• the controllers included in the control-unit group output the I/O output request in synchronization with a group request cycle that is a cycle in which the I/O output request is transmitted,
• the processor further performs a second filtering in which the I/O output request is selected based on the group request cycle and is output, and
• the processor performs filtering in which the I/O output request that includes the operational output based on majority decision is selected and is output as the second filtering, when a different operational output is included in the I/O output requests received in the group request cycle.

A method comprising:

• receiving an I/O output request including an operational output for an I/O output device to operate a plant, the I/O output request transmitted from a plurality of controllers through a network;
• performing filtering in which an I/O output request from a proper controller out of the received I/O output requests is selected and output;
• detecting an abnormality of the I/O output request;
• and
• transmitting, when the abnormality is detected, an alternate I/O output request, which is a request including an alternate operational output, to an I/O output device corresponding to the I/O output request;
• and
• outputting, when the abnormality is not detected, the I/O output request subjected to the filtering to an I/O output device corresponding to the I/O output request, wherein
• the method performs the filtering for each of control-unit group including the controllers that transmit the I/O output requests to an identical I/O output device,
• the controllers included in the control-unit group output the I/O output request in synchronization with a group request cycle that is a cycle in which the I/O output request is transmitted,
• the method further performs a second filtering in which the I/O output request is selected based on the group request cycle and is output, and
• the method performs filtering in which the I/O output request that includes the operational output based on majority decision is selected and is output as the second filtering, when a different operational output is included in the I/O output requests received in the group request cycle.