The Design Of Re-configurable Virtual Instrument Based USB Bus

The re-configurable virtual instrument created a new era of measure equipment, which was produced by instrument technology and the computer technology which developed at very fast speed. The virtual instrument represents the latest development in the direction of equipment that will measure functional and powerful computer hardware combination. It can be customized according to user requirements for high-grade low equipment. With the development of computer technology, the virtual instrument technology will have broader applications. The universal serial bus is a new system of industrial personal computer bus standard, which has many excellences, such as inexpensive, high speed, low power consumption, support plug-and-play and the use of the advantages of easy maintenance. It will be a new current in the cheap-measuring instruments will become a new trend. There papers on the design of virtual instrument based on USB specific start. Virtual instrument is composed of application software and data acquisition card. In particular design, the paper uses USB technology, virtual instrument technology, re-configurable technology and some software and hardware knowledge related to the research on reconfigurable USB virtual instrument system. It has the following functions and features:The first, in this system, the ports of data acquisition card can be measured in accordance with the need to be allocated to the various measuring instruments, all measurement tasks can be distribution according to need;Secondly, there were two customers in the system: High power users and ordinary users. The high power users can manage module's attribute and show position and use this module or not in the framework of the system; according to the measurement tasks, ordinary user can be more than one;Thirdly, this system includes some base instrument function such as voltage meters, current meters, ohm meters, arithmometers, oscillographs, cymometers, spectrum analyzer instruments and signal generators, the number of function instrument can be setting by the need of measurement. The instruments have linkage and trigger function. The linkage function can setting borderline of instrument, deletes the data which not accord with measure condition. The trigger function can set the order of instruments.The last, the system has data storage and data review functions that can be reviewed the measure result; there is visual data system which can simulate data acquisition result without data acquisition card, and the final results be printed.The paper used data acquisition card NIUSB6008 which made by National Instrument Company, accelerate the development pace of the instrument. The programmer language is C#.NET used to reduce the cost of equipment development. This system through an integrated test, the data acquisition card acquires data and transmitted to a computer, then the computer analyze the data, accomplish a re-configurable virtual instrument system based USB. Finally the paper summarizes of the main work, and that the system needs further improvement and development of the hardware and software aspects.