Abstract: A process control system includes: a controller; at least one input and output module connected to the controller; and an allowable propagation delay value calculator in the controller, the allowable propagation delay value calculator being configured to calculate, based on the number of input and output modules connected to the controller, an allowable range for propagation delay time between the controller and the input and output module.

Abstract: A process control system includes: a controller; at least one input and output module connected to the controller; and an allowable propagation delay value calculator in the controller, the allowable propagation delay value calculator being configured to calculate, based on the number of input and output modules connected to the controller, an allowable range for propagation delay time between the controller and the input and output module.

Abstract: There is provided a distributed control system including a plurality of field controllers which are connected through a control network. Each of the field controllers includes: a control clock that defines a control timing of the field controller; and an adjustment unit that adjusts a control time of the control clock depending on a network time obtained through the control network.

Abstract: The field control system includes: a field device; a field controller which is connected to a control network and which executes a computation processing for controlling the field device according to a given control cycle while executing a data communication between the field controller and the field device, the field controller including a communication unit configured to execute the data communication with the field device, and a control computation unit configured to execute the computation processing independently from the communication unit; and an operation monitor which is connected to the control network and which operates and monitors the field device, the operation monitor including a network clock which provides a common network time to the control network. The control computation unit and the communication unit execute the computation processing and the data communication in synchronism with each other in accordance with a timer clock based on the network time.

Abstract: There is provided a duplexed field controller. The duplexed field controller includes: first and second control units between which a control authority is switchable; a first application clock that is updated based on a reference clock so as to define a timing of an application operation of the first control unit; a second application clock that is updated based on the reference clock so as to define a timing of an application operation of the second control unit; and an update control unit that bypasses the first update of the second application clock after switching of the control authority, if the first application clock is ahead of the second application clock when the control authority is switched from the first control unit to the second control unit.

Abstract: The field control system includes: a field device; a field controller which is connected to a control network and which executes a computation processing for controlling the field device according to a given control cycle while executing a data communication between the field controller and the field device, the field controller including a communication unit configured to execute the data communication with the field device, and a control computation unit configured to execute the computation processing independently from the communication unit; and an operation monitor which is connected to the control network and which operates and monitors the field device, the operation monitor including a network clock which provides a common network time to the control network. The control computation unit and the communication unit execute the computation processing and the data communication in synchronism with each other in accordance with a timer clock based on the network time.

Abstract: There is provided a distributed control system including a plurality of field controllers which are connected through a control network. Each of the field controllers includes: a control clock that defines a control timing of the field controller; and an adjustment unit that adjusts a control time of the control clock depending on a network time obtained through the control network.

Abstract: There is provided a duplexed field controller. The duplexed field controller includes: first and second control units between which a control authority is switchable; a first application clock that is updated based on a reference clock so as to define a timing of an application operation of the first control unit; a second application clock that is updated based on the reference clock so as to define a timing of an application operation of the second control unit; and an update control unit that bypasses the first update of the second application clock after switching of the control authority, if the first application clock is ahead of the second application clock when the control authority is switched from the first control unit to the second control unit.

Abstract: A field control device is provided. The field control device includes: a task executing unit configured to selectively and sequentially execute a control task relating to a field control and other tasks in a same control period; and a priority switching unit configured to switch a relative priority of the control task relative to the other tasks in the control period, wherein the priority is a priority of an execution sequence of tasks in the task executing unit. The priority switching unit is configured to: i) set the priority higher than a certain priority, before the control task is started; and ii) set the priority lower than the certain priority, after the control task is ended.