A manufacturer's catalogued part of a PES including Input and/or Output interfaces allowed to operate only under the hierarchy of the Main Processing Unit (MPU), for I/O multiplexing/demultiplexing and data preprocessing/postprocessing. The RIOS is only permitted limited autonomous operation (e.g., under emergency conditions such as breakdown of the communication link to the MPU or of the MPU itself, or when maintenance and troubleshooting operations are to be performed).
Go to Process Safety Glossary