Design And Implentmention Of Virtual Instrument System Software Based-on PXI Bus

The Virtual Instrument system has obtained the widespread approval and application in the world since the concept of Virtual Instrument was firstly proposed by National Instruments coporation in 1986. The powerful software of computer technology is gradually replaceing the traditional instrument hardware. In order to adapt the various changes in instruments and auto testing domian, PXI expands PCI bus which has been defined by CompactPCI to an electricity, machinery and software specification that is sutiable for testing, measurement and data acquisition. Combining the high performance of PC and low cost of PCI bus, the PXI modulars satisfy requirement of high performance, reliability, usability and economical efficiency on various platforms.This paper mainly discussed the software technology based-on PXI platform. The author's main research work is as follows:(1) The concept of PXI system was introduced. The software and hardware specification of PXI were also presented. Then a software architecture on PXI palform was proposed.(2) The design and implemention of instrument drivers of PXI modulars: Now there are mainly 3 kinds of models of instrument drivers. 1) The PCI drivers of WDM for PCI devices under Windows.2) The model of instrument drivers based on VISA which is defined by VPP. 3) The model of instrument drivers which is defined by IVI foudation. In this part of the paper, all the 3 models were introduced firstly. Then a comparison of them was given from designing difficulties, functions and scope of application. Lastly, an instance of instrument drivers of PXI modular was given according to Actual need(3) The design and implemention of PXI system in programmable mode: According to the requirement of forming ATS and compatibility with other buses, a design of IEEE-488(GPIB) compatible instrument on PXI platform was prposed. In this part of the paper, a surney of IEEE-488 bus was given firstly, and then the management of IEEE-488 interface messages, design of status reporting model and the SCPI parser were discussed. A design of an instrument-side ActiveX control and an algorithm of SCPI parser were also presented. The technique discussed in this paper is now applied in a wirless test set based on PXI bus. Besides completes core functions, the system also has a characteristic of low cost, hign stability and portability.(4) A summary and forecast of further work were given.