Switch control between FCS and Ethernet for chemical processes with large time lag

It is not an easy task to effectively control complex chemical processes with large time lag. This job proposes a switch control strategy between a fieldbus control system (FCS) and an Ethernet control system (ECS) for these processes. When a process output is near to its setpoint, a fieldbus control loop is put into action to control the process through a simple control strategy. While the output deviates away from the stet point and the communication load on the sharing bus is lower than a given threshold, the switch event of the control loops occurs from a fieldbus control loop to an Ethernet control loop that implements an advanced control strategy on a supervisory computer. The main merits of this method are: (1) a complex chemical process with large time lag that can be effectively controlled and (2) the network traffic and the computation burden of an advanced control scheme can be substantially reduced simultaneously. The feasibility and the effectiveness are demonstrated by a case study.