The structure-conserving module for network control system based on Petri Nets

Abstract

The aim of this paper is to presents a approach for build a model based on Hierarchical Colored Petri Net(HCPN) for Networked Control System(NCS) with Programmable Logic Controller(PLC) which using formal discrete simulation and modeling First, a structure-conserving timed hierarchal model is built to generate sampled time delay data so that research about time delays would be very convenient, Moreover, compared with the traditional modeling method, the presented model take Data Packet dropout, Date Packet retransmission and Data Packet disorders into account specially. Second, it extracts data from the HCPN model of NCS which include two important time delay for the design of controller in PLC, one is the controller-to-actuator delay τca, and another is the sensor-to-controller delay τsc. Finally, the periodic of time delay will be analyzed using the period grams from the result of simulation The results show that the periodic will be destroyed by the uncertainty transmission time of Ethernet.