Hardware Design And Implementation Of PXI Graphical Multimeter Module

PXI(PCI extensions for Instrumentation)is a PC-based measurement and automation platform released by National Instruments.Due to its high performance and low cost,it has developed into a mainstream virtual instrument and automatic test platform.PXI picture display multimeter is the most commonly used measurement module for building PXI automatic test system.It not only has the functions of measuring AC/DC voltage,current and resistance by ordinary digital multimeter,but also can display the measurement data in real time with time.It can be widely used in basic Measurement of electrical parameters and real-time monitoring of equipment operating conditions.The paper starts with the main functions and technical requirements of the PXI graphic multimeter module,and develops the overall hardware scheme that meets the system requirements.The key circuits are designed and analyzed in detail,and the PXI graphic display multimeter module with measurement and display functions is finally completed.Hardware implementation.main tasks as follows:1.Combined with the requirements of functional indicators,the overall hardware scheme of the system is given.The measurement methods of voltage,current,resistance and other parameters are discussed.The errors that may occur in the design are analyzed.The calculation method for the irreparable error caused by circuit noise is given.The calibration method is proposed for the error that can be eliminated.2.On the basis of the overall hardware scheme,the main measurement function circuit design of the graphic display multimeter module is completed.Including input protection circuit,input signal conditioning circuit,ohmic current source circuit,A-D conversion circuit,storage circuit,clock circuit,analog-digital isolation and power supply circuit implementation.3.According to the system control requirements,the design of the entire control logic and interface circuit is completed.The flexible configuration of the channel,ADC interface and PXI interface enables the FPGA to meet the relevant functional requirements.4.The problems in the circuit debugging were analyzed,and the completed machine function indicators were tested and verified.Experiments show that the module can complete the measurement and display of AC voltage,current and DC voltage,current and resistance.The main test indicators meet the design requirements.