To solve a problem that much time is required up to the notice of abnormality in a remote programmed input/output (RI/O) because abnormality other than the self-diagnosis of the remote PI/O can not be detected between a communication interface of an MCU and the remote PI/O.

An MPU abnormality detection circuit is formed in a communication module of the remote PI/O so that a response from a CAN chip is not returned and the communication interface of the MCU detects the abnormality of the remote PI/O as no response. Consequently a process controlling controller can recognize the abnormality of the remote PICO in which the process controlling controller and a process I/O part are mutually separately arranged and quickly correspond to a countermeasure for abnormality.