Research on Real-Time Simulation of CAN Bus with Priority Promotion Algorithm

In order to analyze and evaluate real-time performance of CAN bus with priority promotion algorithm (PPA), the OPNET model of CAN bus with PPA has been set up in this paper. Based on simulation experiments, the performances of average delay of PPA and Fixed Priority Scheduling (FPS) and Earliest Deadline First (EDF) algorithm are analyzed and the experiments also indicate that in a slight overload condition FPS algorithm makes the transmission delay of low priority data frame increased significantly, and even occurs the phenomenon that low priority data frame can not be sent at any times; EDF algorithm keeps the average delay of all the node at 2ms or so, the objective of scheduling information is achieved, but the average delay of hard real-time node is increased; compared to EDF algorithm, PPA increases the average delay of non real-time node appropriately through using different promotion weights, and reduces the average delay of hard real-time node. The results show that the PPA has the better scheduling and availability in real-time control system.