Automatic Calibration System Based On Virtual Instrument Remote Source

Remote-Calibration is a rising calibration way to calibrate a remote instrument through mediums such as internet. Contrasting to traditional way, it has advantages of higher efficiency and lower cost. This paper based on an actual project requested by Qian Feng calibration laboratory. By means of searching Remote-Calibration's current development, we planned to build a remote signal generator calibration system with wide usage, using VI (Virtual Instrument) technique.This paper first introduced some conception related to VI, and then analysis the VI's architecture of both software and hardware. According to our actual desire, we select LabVIEW8.2 as the software development tool and GPIB as the hardware controller. We have researched almost all the communication method in LabVIEW, and compared the two different kind of communication mode. Finally, we designed our mode as C/S (Client and Server), and choose Shared Variable and DataSocket as the means to achieve our system.System was divided to several modules. We decompose it to server and client at first place. And reduce to communication module, server management module, calibration module etc, until it was decomposed to proper size, to make the system a strong one.Access database was used to save data of both calibration and some other. LabSQL and ADO was used to realize the connection between LabVIEW and Access. With well programming, we can enhance the calibration ability of the system for the huge data saving ability. It can calibrate some items of all the instrument support standard GPIB communication protocol.We try to use a national GPIB card named BC1401 series to replace the expensive NI GPIB card. It was proved that it can be achieved, using DLL in LabVIEW. We also use bestow the feature of polymorphic vi to package the VISA of BC1401 and that of NI, then user can simply use a uniform interface to program in LabVIEW regardless it's BC1401 or NI. This is a good approach to using BC1401 card in LabVIEW.LabVIEW8.2 is an object-oriented language can totally support object-oriented programming. We build the object-oriented model of instruments and use LabVIEW to implement. It's a success test, and it makes sense to the method to realize VI in LabVIEW.LabVIEW can communicate with Word use ActiveX technique. We can design word report, and this is a method to suit traditional report, and prepare for future office without paper.At the end of this paper, the security of this system was discussed, we adopt the MD5 message-digest to encrypt the user password, so that it can be avoid to be used unwarrantable even if the Access database was invaded.The remote signal generator automatic calibration system designed in this paper had been debugged in LAN, and it was proved safe and effective. The debugging between Internet has been processing, it'expected to be used in practice and will bring a great deal of benefit in future.