A control apparatus comprising: an arithmetic device; and one or a plurality of functional units, wherein each functional unit exchanges signals with a control target comprising a machine or a facility, and comprises at least one abnormality detection logic for generating an abnormality log when an abnormality occurs in the arithmetic device, wherein the arithmetic device comprises: a communication circuit, configured to exchange data with the one or a plurality of functional units through a communication line; a processor, configured to execute a user program to perform at least one of an arithmetic processing using data acquired from the one or plurality of functional units and a generation processing of data to be transmitted to the one or plurality of functional units; and a monitoring circuit, connected to the communication circuit and the processor, wherein the monitoring circuit includes: a detection unit configured to detect an event occurring in the arithmetic device; and a storage unit configured to store a message associated with each event; the arithmetic device being characterized in further comprising: a start unit configured to give an instruction to the communication circuit in accordance with the event detected by the detection unit and transmits the message, which is stored in the storage unit, associated with the detected event to the communication circuit, wherein the message for the event comprises a command for transitioning each functional unit to an operation state in which an operation of each functional unit is limited, and the limited operation comprises invalidating of a part or all of the at least one abnormality detection logic. an arithmetic device; and one or a plurality of functional units, wherein each functional unit exchanges signals with a control target comprising a machine or a facility, and comprises at least one abnormality detection logic for generating an abnormality log when an abnormality occurs in the arithmetic device, wherein the arithmetic device comprises: a communication circuit, configured to exchange data with the one or a plurality of functional units through a communication line; a processor, configured to execute a user program to perform at least one of an arithmetic processing using data acquired from the one or plurality of functional units and a generation processing of data to be transmitted to the one or plurality of functional units; and a monitoring circuit, connected to the communication circuit and the processor, wherein the monitoring circuit includes: a detection unit configured to detect an event occurring in the arithmetic device; and a storage unit configured to store a message associated with each event; the arithmetic device being characterized in further comprising: a start unit configured to give an instruction to the communication circuit in accordance with the event detected by the detection unit and transmits the message, which is stored in the storage unit, associated with the detected event to the communication circuit, wherein the message for the event comprises a command for transitioning each functional unit to an operation state in which an operation of each functional unit is limited, and the limited operation comprises invalidating of a part or all of the at least one abnormality detection logic. a communication circuit, configured to exchange data with the one or a plurality of functional units through a communication line; a processor, configured to execute a user program to perform at least one of an arithmetic processing using data acquired from the one or plurality of functional units and a generation processing of data to be transmitted to the one or plurality of functional units; and a monitoring circuit, connected to the communication circuit and the processor, wherein the monitoring circuit includes: a detection unit configured to detect an event occurring in the arithmetic device; and a storage unit configured to store a message associated with each event; the arithmetic device being characterized in further comprising: a start unit configured to give an instruction to the communication circuit in accordance with the event detected by the detection unit and transmits the message, which is stored in the storage unit, associated with the detected event to the communication circuit, wherein the message for the event comprises a command for transitioning each functional unit to an operation state in which an operation of each functional unit is limited, and the limited operation comprises invalidating of a part or all of the at least one abnormality detection logic. a detection unit configured to detect an event occurring in the arithmetic device; and a storage unit configured to store a message associated with each event; a start unit configured to give an instruction to the communication circuit in accordance with the event detected by the detection unit and transmits the message, which is stored in the storage unit, associated with the detected event to the communication circuit, wherein the message for the event comprises a command for transitioning each functional unit to an operation state in which an operation of each functional unit is limited, and the limited operation comprises invalidating of a part or all of the at least one abnormality detection logic.