Software Development Of Helicopter Test System Based On CAN Bus

With the modernization of our national defense and the rapid development ofthe national economy, the improvement and modification researches of helicopterget unparalleled development. However, the development of test system forairborne equipment restricts the helicopter production, application and maintenance.CAN, which is an asynchronous serial data transmission protocol, has been widelyused in the field of embedded real-time control and distributed control, so we use itin the test system. But CAN is incomplete, different applications manufacturersmust design the application layer according to their own hardware system. In orderto achieve the scalability of helicopter test system and implement theinteroperability and interchangeability of the ATE module, CAN nodes should beable to automatically or dynamically configure network identity. CAN, in fact, doesnot have a mechanism to allocation the network IDs of the nodes that do not have anassociated identity in an efficient and reliable way when they have already beenconnected to the network. Now, the network ID of CAN node often is fixed adefault number or manually configured. Going deep into studying CAN applicationlayer specifications and achieve the automatic configuration of CAN node’s networkidentifier are helpful to perfect software of the test system.In this paper, an analysis for the Physical and Data Link Layer of CAN and itsApplication Layer such as CANopen is given. The application layer protocolincluding the framework, the assignment of message-identifiers, acknowledged orconfirmed data transfer, and the transmission of data blocks longer than8bytes isdeveloped according to the helicopter test system hardware, which makes rules forthe development and programming of the ATE module and the future design of thetest system’s application, in turn it is good base for the higher application.Taking into account CAN application layer protocol developed and existinghardware, an automatic configuration algorithm for network IDs of CAN nodesbased on the client/server network model is proposed. The algorithm can be dividedinto two stages: recognition of the function and allocation of network ID. Type ID isused to recognize the test function and network state machine is used to assignnetwork ID, both of which realize the algorithm together.Based on the analysis of CAN232MB configuration, transparent mode withidentification is used in the system. And in order to realize data transmission inorder, the time interval between RS232frames is fixed and frame filtering is used.The client of the automatic configuration algorithm in TMSF320F2812is designedby CCS3.3, and there are transmission failures and message losses in the communication process of emulation debugging. Aiming at pointes, optimizationsfor data transfer are proposed, such as timeout interrupt and retransmit at discreteintervals of time. At last, the software interface for running status of the test systemis developed. Above all, these lay a foundation for CAN communication ofmaster-slaves in the system.An overall framework based on the producer/consumer design pattern withcluster is developed in LabVIEW. In the framework, the server of the automaticconfiguration algorithm is created, resource layer which is used in configurationand running of the test system is built with Access database and the software withdynamic loading of module VIs based on subpanel is set up. The above designs inPC achieve automatic configuration of all nodes on the CAN-bus and lead toindependent testing and joint testing of ATE modules.Finally, the experimental platform for the test system is constructed. Theautomatic configuration algorithm for network IDs of CAN nodes based on theclient/serve and dynamic loading of module VIs in the situations where nodes ownthe same type ID or different type IDs are illustrated by experiments. The resultsshow that the software developed is stable and reliable.