Design Of Pxi Digital Multimeter

With the high-speed development of industrial technology and the emergenceof a variety of complex electronic systems, the traditional measuring instrumentshave been difficult to meet the needs of increasingly complex research tests. To thisend,this paper has designed PXI digital multimeter module based on PXI bustechnology, which is one of the most basic measurement modules of setting up PXIautomatic test system. The main function is to implementAC and DC voltagemeasurement, current measurement and resistance measurement.The designed PXI DMM in this paper adopts the modularization idea on thehardware circuit structureand which divides the PXI DMM into PXI interfacecircuit, DMM function circuit and isolated circuit. PXI interface circuit uses FPGAto implement PXI interface functions and data transmission functions. DMMfunction circuit uses STM32F103RC as the main controller to achieve the switchingof function and range as well as acquisition and transmission of the measurementresults.Also, the adoption of BB's24A/D converter chip—ADS1271helpscomplete the conversion of analog signal to digital signal, while through eachconverting circuitit completes changing the signal to be measured to the DC voltage,and uses the conditioning circuit and filter circuit for signal processing.Then theisolated circuit effectively completes opto-couplers isolation between PXI interfacecircuit and DMM function circuit to reduce crosstalk.In the matter of software, this paper is designed to be strictly accordance withthe relevant provisions of PXI, and use NI LabWindows/CVI software to completePXI DMM softpanel and driver. Meanwhile, this paper is based on the support ofRealView MDK software development tools to complete the writing and debuggingof STM32master control program.Finally, the PXI DMM has been calibrated and tested. At the same time, asuitable calibration model has been established in accordance with actualmeasurement results for PXI DMM calibration. Then each function and range of themultimeter has been tested, errors and uncertainty analysis of the DMM have beenconducted according to the test data. The test results show that the designed PXIDMM reaches the predetermined index, which verifies the rationality and feasibilityof program in this paper.