Design And Implementation Of CAN Network Management Module In NS2

With the fast development of The automobile industry,people show newdemands for safety, energy saving, information and entertainment in vehicle.So thenumber of ECUs in vehicle network is increased,and it makes all vehicle networkshould run in a network management system with high reliability.Thus it is ability toReal-time monitor the communication state of ECUs which related to security (suchas the braking system)in vehicle.Timely process the entry and exit of ECUs in thecommunication network,or some unit’s communication faults. Any of the automobilesafety imagination are empty without a safe and reliable control system.Therefor it isnecessary for solving automobile safety to join a rational-designed networkmanagement scheme in vehicule network.At present,there are some developed software and standards of networkmanagement.For example,the direct network management in OSEK/VDX developedby the famous automobile manufacturers,such as BMW,and other electronicsmanufacturers; AUTOSAR (Automotive Open System Architecture) standard jointlylaunched by the global car manufacturers, the suppliers and other RelatedCompanies.They both have a better development space.This paper makes a detailed study on the OSEK NM standard.According to thecharacteristics based on CAN protocol,make appropriate adjustments on logicalrelationship between nodes, the state transition, logical successor modificationjudgment and skip decision theory in the OSEK standard,and apply in the CANnetwork.It becomes a module in the CAN nodes application layer,called CANnetwork management module.This module has expansed the function and the properties of the original CANnetwork module to implement the function of OSEK NM,and been compatible withthe communication function of the original CAN module.Bind the CAN node to theagent module,and realize the real-time monitoring of network nodes by receivingdedicated NM message. The CAN network management module designed based on the OSEK directnetwork management standards runs well. NM messages and CAN applicationmessages arbitrate and competite on bus normally. According to detailed analysis ofthe trace file,the performance of CAN network management module is not ideal insome special cases.It shows in the following three points:1. Node has a slow speed as entry the network.2. Nodes skipped when new nodes to be on-line.3. When the number of transmitting CAN message increases, NM messagesand app messages interaction.It reduces the real-time performance of CANnetwork and has some impact on the network management.According to the detailed analysis of these problems, corresponding adjustmentand optimization of the on-line process and NM Ttyp timer has made in this paper.Reduced the node on-line time,and avoided occurring node skipped as a new nodeentry network. When the number of app message and NM message conflicts over aperiod of time exceeding the prescribed number, NM Ttyp timer should beprolonged.When during a long time there is no conflicts arise, shorten the timer.Real time have improved of the optimised CAN network,and the efficiency andstability of NM module’s function has also been improved. According to analysis ofthe experiment result,the improved CAN network management module hase highsecurity to the safety and reliability of in-vehicle network, it also promote thedevelopment of the automobile safety.