In the conventional distributed control system, since each control device updates the data area at a timing when a control packet is received, in a case where there is a difference in communication delay between the control devices or in a case where the communication delay includes jitter, it is difficult to match the contents of data in all the control devices in a case of focusing on a certain moment during system operation. Therefore, depending on the start timing of a control application, the control application operates on the basis of different data between the control devices, thus limiting control performance improvement. Accordingly, time slots on the network are allocated according to the result of a calculation unit, and a cyclic memory synchronization update unit synchronizes the timing of reflecting data in the input/output and the cyclic memory and the timing of using data of a cyclic memory.

A controller includes a processor and a communication circuit. The controller controls an object of control by sequentially repeating, on a predetermined control cycle, the transmission of the output data, the reception of the input data, and execution of a control program for generating the output data using the input data. In the transmission of the output data, the processor executes: storing of the output data in a frame, the output data having been generated by the execution of the control program in a previous control cycle; and control of the communication circuit such that the frame, in which the output data is stored, is transmitted to the object of control. The processor executes, in a current control cycle, at least a part of the storing of the output data in a frame that is to be executed in a next control cycle.

A controller includes a processor and a communication circuit. The controller controls an object of control by sequentially repeating, on a predetermined control cycle, the transmission of the output data, the reception of the input data, and execution of a control program for generating the output data using the input data. In the transmission of the output data, the processor executes: storing of the output data in a frame, the output data having been generated by the execution of the control program in a previous control cycle; and control of the communication circuit such that the frame, in which the output data is stored, is transmitted to the object of control. The processor executes, in a current control cycle, at least a part of the storing of the output data in a frame that is to be executed in a next control cycle.

A controller performs a control operation associated with a control target. The controller includes a communication interface that electrically connects at least one function unit to the controller through a data transmission path, a writing unit that writes an observation value obtained through the function unit into a database, and a delay obtaining unit that obtains a delay time taken from when a signal indicating an observation value is input into the function unit to when data representing the observation value becomes usable in the controller, and stores information indicating the obtained delay time.

In the conventional distributed control system, since each control device updates the data area at a timing when a control packet is received, in a case where there is a difference in communication delay between the control devices or in a case where the communication delay includes jitter, it is difficult to match the contents of data in all the control devices in a case of focusing on a certain moment during system operation. Therefore, depending on the start timing of a control application, the control application operates on the basis of different data between the control devices, thus limiting control performance improvement. Accordingly, time slots on the network are allocated according to the result of a calculation unit, and a cyclic memory synchronization update unit synchronizes the timing of reflecting data in the input/output and the cyclic memory and the timing of using data of a cyclic memory.

A controller performs a control operation associated with a control target. The controller includes a communication interface that electrically connects at least one function unit to the controller through a data transmission path, a writing unit that writes an observation value obtained through the function unit into a database, and a delay obtaining unit that obtains a delay time taken from when a signal indicating an observation value is input into the function unit to when data representing the observation value becomes usable in the controller, and stores information indicating the obtained delay time.