Automatic & Semiautomatic Calibration System Design Of Digital Multimeter

Digital Multimeter(short for DMM) measurement, as a common test instruments verified in professional measurement and test department, is verified according to 5 verification regulations. The results of measurement uncertainty are calculated by means of JJF1059-99, the Evaluation and Expresssion of Mesurement Uncertainty. The paper makes a theoretical analysis of measurement uncertainty and round calculation. Keithley 2000, a type of DMM made by a U.S. Company, an experimental modle, is verified with two computer-aided automatic verification programs designed by Met\Cal and LabView respectively,in order to improve efficiency, reduce work intensity and error..The first method is to use Met/Cal, the U.S. calibrator manufacturer Fluke's metrology software development platform, to edit Keithley 2000 DMM verification program. The paper describes the basic functions, workflow, and parameters setting of measurement uncertain and the main content of the verification program. For the hand-held DMM, with no I/O interface, the paper describes in detail three kinds of semi-automatic verification programs. Finally. a verification program for VC97, a hand held DMM made by Victory, is designed and taken as an example.After considering the advantages and disadvantages of current text-based automation verification softwares and real demands of domestic DMM verification. LabView is used to design general DMM verification programs. In the newly designed software, some improvements are made, compared with Met/Cal, to make DMM auto-verification more convenient, flexible and easy to use.