The Virtual Instrument Testing Platform Based On USB Bus

The development of sclence,production and community have expounded demand to testing higher and higher.With the testing objects changing from a single static parameter to several active ones,even a group of active courses,apparatus have passed through the way of analog,digit,brain and virtual.That the technology and apparatus of testing will follow the develop tendency of computer has already popular in testing field.The virtual instrument has been mentioned for years,but it still in the stage of studying,discussing and probation.This paper try to use the universal serial bus popularity in personal computer as a core to constitution the virtual instrument testing platform,including understanding of criterion,studying of interface,manufacting of devices,develop of software and constructing of system and so on.The aim is to put the virtual instrument to applying quickly,using this new convenient,flexible,efficient and cheap method.This paper first begin with the connotation of virtual instrument technology,study and discuss the criterion and the working theory of USB deeply.On the principle of USB1.1criterion,using USB interface chip USBN9604 and low consumption mirochip C8051F231,we designed the available interface of USB bus and its controlling software,turn the communicating function based USB bus between computer and testing device. Second based on the developed interface of USB bus,using microchip PIC16C62 and a mount of relays,we designed the multiswitching scanner and its controlling software to complete the funtion of accesses swithing in testing system.Third calling the API function inside the windows using VB programming language,communicat with the impelling program of selected HID,achieve the function of testing instrument with USB interface,complete the development of upside software faced testing.At last,based on the deep studying of PCB testing method,used the developed multiswithing scanner and software faced testing,combinated with necessary testing instrument ,we constructed the PCB testing system and analized the testing result simply.