Realtime characteristic of FF like centralized control fieldbus and its state-of-art

The temporal property of MAC protocol of fieldbus is critical to meet real-time constraints of field devices in factory floor. Among various types of MAC protocols, the one using centralized strategy is characterized by providing a feasible schedule to meet different temporal constraints of field devices online, and also providing schedulability analysis offline a priori. WorldFIP and FF, two popular international standards of fieldbus, both adapt a centralized strategy, which is mainly implemented by schedule table (ST). This paper mainly discusses how to construct ST including size of ST schedule algorithm and schedulability analysis, to meet requirement of field devices on response time, jitter, synchronization, and its state-of-the art.