The Software Design Of 6 1/2-digit PXI Multimeter Module

Digital multimeter is a kind of multifunctional electronic measuring instrument. It is applied to engineering detection and error diagnosis widely. Compared with the traditional multimeter, modular digital multimeter is provided with a smaller size, higher performance, lower cost, and it is commonly applied to the measurement and automation system platform. In this thesis, the 6 1/2 digit PXI multimeter, presented itself as a board, is based on PXI bus. The users can actually operate the multimeter module only by the instrument software, so efficient and flexible instrument software is indispensable. In order to meet the demand of the domestic users and promote the level of PXI instrument testing in China, the study in this thesis is very meaningful.The main task of this thesis is to design software for 6 1/2 PXI multimeter modules. The multimeter in this thesis is provided with the function of digitizer except the basic test function, thus the software design includes the realization of all testing functions and the digitizer’s functions. This thesis proposes the overall software design scheme of the 6 1/2 PXI multimeter. The soft panel has been designed friendly with the advantages of a variety of common multimeters’ soft panels, and instrument driver has been designed according to IVI specification. Furthermore, the function of digitizer attached has been realized. To sum up, the main contents of this thesis are as follows:1. Design the application software of the digital multimeter with digitizer function. The soft panel of the multimeter is mainly to achieve the basic measurement, mathematical operations, Chinese-English switching function and so on. The soft panel of the digitizer is mainly to achieve stable waveform display of AC and DC voltage. Besides, it is with a simulate waveform display function attached.2. Design of instrument driver of the multimeter module. The basic driving functions are designed according to the IVI specification. Besides, some custom driver functions, including the multimeter calibration functions and relative digitizer function are added. The design of instrument driver makes test program development and maintenance becomes simpler and easier.3. In order to improve the precision of the multimeter, the analysis of error and methods of data processing are needed. The error is devided into system error and random error. The coefficient calibration method include the linear spline interpolation to eliminate the system error, the low pass filter to eliminate the high frequency random error data, the weight filtering method also to eliminate the random error of the multimeter are adopted. The data analysis indicates that this method is accurate and effective.The software design of 6 1/2 PXI multimeter achieves accurate and stable measuring function and digitizer function, and it is really easy to operate. This thesis describes in the three aspects as follows: soft panel, IVI instrument driver and the calibration method. At the end of this thesis, there is an overall test of the software functions, and the test results show that the software has achieved the expected goals.