Development Of Tractor's Virtual Instrument System Based On CAN Bus

Along with the continuous improvement of technology, advanced the course of agricultural modernization which includes automated, intelligent, GPS navigation and remote control in the agricultural machinery. The rapid development of electronic technology and computer technology and its application in the tractor have improved the operating performance and the ability of the tractor. Electronic sensing technology, computer information processing systems and liquid crystal digital virtual reality display technology have been used to tractor in abroad. Especially CAN Bus technology also has becoming mature. But in our country, the research of CAN bus technology and virtual instrument technology in the Tractor is still at the exploratory stage. According to the current limit of the traditional tractor instrument, a tractor's virtual instrument system based on CAN Bus was put forward in this paper. This system combines CAN Bus technology and virtual instrument technology. It will not only completely change the way of data communication and instrument display in the tractor, but also offers reference for the more research of the tractor in future.Base on the application layer protocol SAE J1939 which was made in the United States agricultural engineering for agricultural machinery, a framework and application layer protocol of CAN bus in the tractor. So the holistic design scheme of tractor's virtual instrumentation systems based on CAN bus was brought forward. Described the virtual instrument technology and its software exploitation flat roof, and advanced the collectivity flow of virtual instrument.According to the requirements of the holistic design and CAN bus, the corresponding hardware circuit and software program were designed. The network hardware structure of tractor's CAN bus included node circuit of the engine system and the display circuit of instrument, which used MCU C8051F040, CAN transceivers PCA82C250, and photo-electricity isolation coupler 6N137. And then, the application program of tractor's CAN nodes were compiled. Base on the requirements and features of the virtual instrument technology, the software development process of the virtual instrument system was designed. Virtual instrument system software was developed by the graphical programming language LabVIEW. The interface designing and programming of the virtual instrument system were achieved combined with the man-machine engineering principle.Tests of CAN node communication and virtual instrument display system were designed combining the collectivity design. The CAN node communication test platform was made up of the engine node circuit, the CAN analyzer, the waveform generator. Data communication between nodes was achieved by this test, and the reliability of the CAN node circuit was verified. The virtual instrument display test platform consists of the data acquisition card, common rail diesel engine system, industrial computer and other connecting devices. Engine revolution signal was collected and displayed by this platform. From the analysis of testing results, we have seen that the display errors of the virtual instrument system were basically in the test allowable error area. So it was verified that the virtual instrument display system was feasible and ascendant.