Transmission of a Scheduled Message Using a Foundation Fieldbus Protocol

In the last decade, process instrumentation field devices such as sensors and actuators that have a direct contact with industrial processes have become increasingly intelligent. An important property of such intelligent field devices is their ability to be networked. The Foundation fieldbus (FF) is one of the most widely used fieldbus protocols for process instrumentation and control systems applications. This paper presents a study that validates the effectiveness of a new scheduling method that satisfies the performance requirements for a scheduled message using an FF protocol. Our scheduling method generates a schedule list that records the scheduled starting time and the scheduled period of each scheduled message. Then, it allocates scheduled message traffic to a bandwidth-limited fieldbus medium. As part of this study, an experimental model of an FF network was developed. The experimental results from our model confirmed that our scheduling method restricts the delay of a scheduled message to a prespecified bound.