The Study On The Circuit Application Of PCI Bus In Open CNC

CNC(Computer Numerical Controller) taking the technique of PC just develops into the current of world and will be a leap having the most profound meaning to NC technique. Usually it means that movement controller (open CNC) or CNC function module plugs into PC bus slot, and uses the standard hardware platform and operate system. While the interface technique between PC and CNC module is the important guarantee for the system stability and its high-speed performance.This paper carries on the research to the application of advanced technique of PCI bus.Aiming at the interface design it researches and discusses in three vital links-PCI busprotocol, realization of hardware interface circuit and drivers development. It enunciates the theory of PCI bus operation, puts forward two concrete projects of developping the PCI bus that one is using ASIC and the other is using special interface chip.Discuss the project each from advantage to shortage and do analysis and argumentation. On this foundation, one path is found that has a higher proportion when its price compares to its ownperformance-taking the chip of PCI9052 as the key subassembly and use it as thekernel of PCI hardware circuit in the open CNC. Then get the technique target.According to the PCI bus protocol, this paper studys the experiment circuit with holding the function characteristics of its abrupt data transfer. The paper researches the techniques of D/A and A/D conversions with high or low speeds through multiple channels. Choose the chip DAC7724 of TI-BB Company and the chip ADC7865 of AD Company. Study their structure, principle and control methods. In order to satisfy the request to real time and levity(delay and wait) by function modules for data communication in open CNC, the paper not only makes use of the PCI9052 multi-function characteristics well, and but also develops the bus drivers to the hardware equipment. It will make the system control to hardware more flexible and valid.The paper develops drivers according to the Windows 2000 WDM. The operate system of Windows 2000 has the mature structure system, and is compliant to higher request of the industrial control system for the securities and reliabilities. The paper studies the principle and structures of the WDM drivers, and discusses general process of developing PCI drives with the Device Driver Kit(DDK) from Microsoft.The software package of Compuware Company's DriverStudio realizes the encapsulation to the DDK. It complies with C++ and is object-oriented namely. The paper makes use of the DriverStudio kits and then programs, adjusts the PCI drives aound the function modules followed by the PCI equipment initialization, configuration space accessing, I/O operations, memories read-write etc. The result indicates DriverStudio is a kind of efficiently, practical development tool, and shortens the software development cycle of PCI bus.PCI bus satisfies the development request of the open CNC system's interface. The paper accumulates some practice experience of studying and resolving the key technique for one kind of open CNC systems-the multiple axes movement controller.