Design And Implementation Of Grain Situation Monitor System Based On CAN Bus

The CAN bus is one of the popular field-buses at present, which is more highly reliable and low priced, and being used more and more extensively. In this thesis, a kind of new-type digital grain situation monitor system, based on CAN bus communication network, is studied and designed, which can monitor situation of grain greatly.First of all, the development status and performances of CAN bus are introduced briefly in the thesis, the correlative functions of Physical Layer and Data Link Layer are analyzed, and the main content of technical specification of CAN bus is explained in detail.Secondly, in order to show the application of CAN bus in actual project, the design of grain situation monitor system is given for an example in this thesis. According to framework of the system, the whole design is divided into two parts. One part is the design of monitor module of warehouse based on CAN bus, which can realizes data communication, temperature and humidity measurement, ventilation control, etc. In the design, the hardware and software of the interface of CAN bus are introduced, and the 1-WIRE bus technology of temperature measuring network is discussed; Another part is the design of CAN bus network adapter, which is a difficulty in this thesis. A project of design of CAN bus network adapter based on USB interface is put forward, the controller PDIUSBD12 is used to realize communication to the PC by USB bus, and the virtual device driver is developed by the third software development tool WinDriver. Furthermore, the development flow of adapter is discussed, and the agreement and contents of USB bus are introduced in detail.Finally, the performance of CAN bus protocol is analyzed in the thesis. On one hand, the non-destroyed bit-by-bit arbitrate regulation adopted by CAN bus is analyzed; On the other hand, the mathematical analysis is carried out to explainthe throughput of CAN bus, the performance of CAN bus is proved more superior by comparing with other medium accesses of computer network.