Design And Application Of Intelligent CAN And 485 Card Based On PCI Bus

CAN bus and RS485 bus are two kinds of buses that have been used widely in industy. CAN bus has outstanding reliability, real-time and flexibility in the data communications. The features of RS485 bus are simple structure and long distance. They have broad application prospects in the field of industrial control. With the increasingly powerful computer performance, computer technology has been widely applied. Some industrial control processes also need the computers to monitor system, so we need an interface to implement communication of the underlying network and computer. PCI is the mainstream bus structure of the computer. It have high transmission speed and may achieve Plug and Play. This article has designed a kind of CAN, RS485 bus interface card based PCI bus.Based on the Analysis of PCI, CAN and RS485'Features, we determine the programs of hardware and software . In the design of hardware circuit, in order to make the interface card have some intelligence, reduce the PC's burden and increase reliability, the circuit add the microprocessor in interface card. The hardware uses the PCI interface chip, dual-port static RAM, microprocessor and CAN/485 chip. This paper describe the various parts of the circuit schematic in detail. In software design, this article shows the detailed program flow chart of the initialization of the SJA1000 and the serial port, CAN and 485 data's sending and receiving.This design uses the WDM to develop driver. Based on the study of WDM's principle, this paper describe the structure of the PCI driver by DrvierStudio. Before developing PCI driver, we need to configure PCI9052 configuration space. EEPROM's configuration have a great influence to driver's development. This paper explains the EEPROM's configuration in detail. In the driver development, this paper proposed a method of data protection: the spin-lock mechanism. By this method, the driver may avoid data access conflicts. Finally,we used MFC of VC++ to package the driver for the dynamic link library, and used the functions provided by the dynamic link library to develop the test software.We used the CAN nodes and 485 nodes developed by ourselves to test all the interface card's function. Moreover, and applied the interface card to a actual project"car CAN module test system". The PCI-CAN/485 interface card can be applied widely to various test systems, and has a strong practical value.