Field control system

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.