This article first studies the types and structures of meters, understands and analyzes the structural principles of car speedometers, tachometers, water temperature gauges, fuel gauges, odometers, various LED warning lights, LCDs, etc. and their display principles, and analyzes them. Working parameters and national standards of these tables, etc., then build a hardware platform, design software programs, and then connect the software and hardware, set parameters, and test. This article is to study based on the LabVIEW test system, so in this article, LabviEW is used as the software platform of the portable automobile instrument detection system. In the research, we use LabVIEW as the display of instrument test results and the input of instrument signals, so LabVIEW also One of the important contents of the research. The research content of this paper also includes the communication module in the car. In this paper, the CAN bus and the PXI board are used, so in the research, we have to study how they communicate in the car, and how to connect so that we can get the fastest and most accurate data. Main work : 1. Investigation, research status and problems of portable automobile instrument detection system. Analyze various automobile instruments, and then analyze, process and synthesize the data. Consult relevant materials, determine research topics, and make feasibility analysis. 2. Build the relevant hardware and software platform of the portable car instrument detection system based on LabVIEW. 1) Hardware platform: The hardware system of the automotive instrument test system mainly includes an industrial control computer (which is the brain of the entire control system), a PXI board (PXI6528 is a static digital FO board, specifically for certain slow-changing digital signals, and has 24-channel input and 24-channel output can both collect digital signals and output externally), signal junction box, data communication conversion board, CAN card, programmable network resistance, power supply and tested instruments. 2) Software platform: The instrument detection system software is designed using the LabVIEW platform of Nl Company. The system uses the graphical programming language of LabVIEW to establish a front panel man-machine interface and program block diagram in a very intuitive way. 3. Repeated experiments, compared with other automobile instrument test systems, combined with the actual test results, repeatedly verify the correctness of the evaluation and detection system and the effectiveness of the evaluation software. This article uses Nl's hardware and software products and a self-developed data communication conversion card. According to various analog, digital, switch, CAN and other signal parameters required by the portable automotive instrument detection system, Nl's PXI board and The data communication conversion card is connected to the hardware circuit. Based on this hardware, the entire test system is developed through the LabVIEW software platform of Nl Company, and finally a complete portable automobile instrument detection system theory is proposed. Chapter 2 Design Plan 2.1 Feasibility analysis 2.1.1 Structure and advantages of virtual instruments The emergence of virtual instruments is a breakthrough in the field of measuring instruments. It has completely changed the traditional viewpoint of instruments, fundamentally updated the concept of measuring instruments, and brought people a new concept of instruments. Virtual instruments represent the latest direction and trend of the development of measuring instruments. It is a computer-based software instrument, with the computer as the core, the instrument functions are loaded into the computer, and various instrument functions are realized through the computer. Common virtual instrument formation schemes are shown in Figure 2-11 The composition of virtual instrument: The virtual instrument is composed of two parts: general instrument hardware platform (referred to as hardware platform) and application software: 1. General instrument hardware platform The hardware platform that constitutes the virtual instrument has two parts: one part is a computer, generally a PC or workstation, which is the core of the hardware platform; the other part is a 1/0 interface device, which mainly completes the acquisition, amplification, and simulation of the input signal under test / Number conversion, etc. Different interface devices (cards) can be used according to the actual situation. Such as data acquisition card / board (DAQ), GPIB bus instrument, VXI bus instrument module, PXI bus instrument module, serial instrument, etc. In terms of hardware structure, the virtual instrument has completely deviated from the original concept of a single instrument. It is not the function of a certain instrument on the computer, but the concept of a virtual instrument system. The structure of the virtual instrument system is shown in Figure 2-2. 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