A PARALLEL DISCRETE EVENT SIMULATION METHODOLOGY OFDISTRIBUTED CONTROL SYSTEMS USINGOBJECT-ORIENTED PROTOCOL MODEL AND TIME WARP MECHANISM

摘要

Recently, distributed control systems (DCS) consisting ofrnmany devices and an open network interconnecting them, arernused in many automation areas. For assuring the controlrnperformance under heavy communication traffic, the accuraternDCS simulation is strongly needed. For this purpose, wernpropose a parallel discrete event simulation methodology ofrnDCS using an object-oriented communication protocol modelrnand Jefferson’s Time Warp mechanism. The protocol modelrntransforms from discrete events sent by the finite state machinernof device model to packets generated by the protocol layers,rnand also transforms into an opposite direction. The Time Warprnmechanism assures that the device model can communicate allrnthe packets in correct order by adding the send time and thernreceive time to the packets. By using the mechanism, the finiternstate machine and protocol model in the device model canrnprogress the logical time, keeping the causality. We developrnDCS simulation software for synchronizing the device modelsrnby applying the simulation methodology to the Java-based DCSrnsimulation model implemented by using object-oriented designrnpatterns. Finally, we confirm the usefulness of the software byrnthe LonWorks-based DCS simulation for factory automation.