Lng Cylinders Monitoring System Based On Can Bus In The Research And Implementation

This thesis mainly discusses the research and implementation procedure of LNGlow-temperature equipment monitoring system which based on CAN bus. UsingPIC18F45K80chip microcomputer as master control chip, which is produced byMICROCHIP, and work in coordination with precise sensor, the system equipmentaccomplishes real-time supervisory control on liquid level, hydraulic pressure, enginepressure of LNG low-temperature equipment, at the same time, by using CAN bus andSAE J1939standard to achieve data communication. The thesis amply studies CANbus, and explains requirement analysis of LNG low-temperature equipment monitoringsystem, and also, gives a fully explanation of the design of system hardware circuit,data collection and transmission.At first, this thesis analyses the background and development of LNG equipmentmonitoring system, through the study of the shortcomings of the existing systemproposed this system of improvement, then studies on CAN-bus which is widely usedin current automotive industry. It is aimed at the accomplishment of hardware circuit,giving the model selecting of chip and the analysis of interface circuit design, and thendetailedly explains software implementing process of system modules, at the end, bysimulation test, it completes performance test of Software and Hardware and identifiesthe stability and availability of the whole system.The implementation of this system is through the PIC18F45K80which provides awealth of peripheral functions. The system functions include monitoring datacollection, transmission and calibration. Cylinder liquid level measurement, the systemuses the capture function of the chip to provide the CCP modules, using a capacitivesensor measurement can be achieved. Cylinder hydraulic and engine pressuremeasurements using the chip to provide the A/D converter module, combined with anexternal high-precision pressure sensor to complete. According to data measurementresults, transmission of data is divided into three ways. The errorless data is sent in thenormal format, and the mistake one is send by DM1frame format, these two waysbelongs to initiative transmission. Lastly, another requested data DM2is false statistic information in the whole life cycle of system, which make the maintenance of systemconveniently.Data communication according the CAN protocol and SAE J1939standards to develop a detailed communication frame format and the interactiveprocesses in the transmission process. In the part of system testing, by simulating avariety of usage, data collection, accuracy test, observe the data communicationthrough a number of supporting software, to verify the reliability of the system.As more and more cars burn LNG as fuel, the study and accomplishment ofcorresponding high performance equipment is inevitable and necessary. Theaccomplishment of system will solve the prominent problems that exist in similarequipments, e.g. large error, low efficiency and inconvenience. This system has comeinto a testing stage at the present time and it should make better economic benefits andsocial benefit in the future.