The Simulation Study Of CAN-bus Network Based On OPNET

With the continuous development of information technology, network scale and topology grow increasingly complicated and application scenarios show itself in a trend of diversification, which makes network design and planning, equipment R&D and corresponding protocol development more challenging, and thus, it is necessary to predict the performance of network by a scientific measure so that network simulation technology emerges.CAN bus is a common industrial field bus communication technology, which supports distributed real-time control and multiplexing for use within road vehicles and aerocrafts.This paper focuses on two aspects. Firstly, making CAN-bus as the research object and OPNET as simulated tool, we apply the method of HLA to build a distributed simulation system. The system is based on OPNET and WINDOWS project, and is composed of three subsystems, including OPNET simulation networks, console and parameter display terminal in which OPNET, C# and HLA programming technologies are used. In addition, in OPNET subsystem, we apply the method of network simulation to build link model, process model and node model for CAN-bus. Based on these models, a CAN-bus simulation network is constructed, which is composed of eight CAN devices.MAC layer is the core of the data link layer of CAN protocol. We designed two process models for MAC layer in consideration of whether there are access conflicts, in which conflict-free access and bit arbitration mechanism are adopted. We can make digital simulation study of CAN-bus by using distinct conflict resolution mechanisms. Moreover, based on HLA technology, we can transfer and transform between real data in WINDOWS subsystem and virtual data in OPNET subsystem. Therefore, the system can also be used to make distributed simulations or even hardware-in-loop simulations. Thus, it is more flexible than OPNET simulations.