Abstract: Based on the current status and future development trends of the industrial automatic control field, this paper proposes a comprehensive testing system design scheme based on virtual instrument technology. The paper details the design concept, structural composition, implementation method, and functions of a comprehensive testing system using LabVIEW language, with data acquisition cards and general-purpose PCs as core hardware resources. Compared with traditional testing systems, the comprehensive testing system based on virtual instrument technology has the advantages of strong operability, good versatility, high cost-effectiveness, powerful functions, speed and convenience, and the ability to realize automatic data acquisition and remote online real-time monitoring, thus having broad application prospects in engineering practice. Keywords: Virtual Instrument, Integrated Measurement, Data Acquisition Card, LabVIEW [b][align=center]Integrated Measurement System Based on Virtual Instrument Technology Que Hao, Yue Rui-hua[/align][/b] Abstract: With a view to the present situation and future development of the industrial automatic control domain, this paper provides a design scheme for an integrated measurement system based on virtual instrument technology. Taking a data acquisition card and a generic human-computer as the primary hardware and using the LabVIEW language to design and develop an integrated measurement system, this article discusses in detail the system design idea, framework, realization method, and function. Compared with traditional measurement systems, the integrated measurement system based on virtual instrument technology takes advantage of its good maneuverability, convenient operation, strong functionality, and ability to realize automated data acquisition and remote online condition monitoring. The system has wide applications in practical engineering. Key words: Virtual Instrument, Integrated Measurement, Data Acquisition Card, LabVIEW 1 Introduction With the rapid development of virtual instrument technology, the "virtualization" transformation of measurement and control platforms has become a trend. Under the influence of this trend, we combined virtual instrument technology with the original measurement and control platform to establish a comprehensive test system based on virtual instrument structure in order to improve experimental conditions, improve test efficiency, and make data processing faster and more accurate. Virtual instruments and technology will become an important method and means in the field of industrial automatic control, with a very broad development prospect. [1] 2 System Composition The system is mainly composed of two parts: hardware and software. The hardware platform adopts the PXI (PCI extensions for instrumentation) bus system, and the software platform adopts the LabVIEW (laboratory virtual instrument engineering workbench) visual graphical programming platform of NI. 2.1 System Hardware Structure The hardware of the system mainly consists of sensors, signal conditioning modules, PXI host, PXI-4472 data acquisition card and network server. The system hardware structure is shown in Figure 1. [align=center] Figure 1 System Hardware Structure Diagram[/align] (1) Selection of PXI host: PXI initially could only use embedded controllers (zero slot controllers). Later, NI released the MXI-3 interface, which expanded the system control of PXI. The application scope of PXI has been expanded, including direct PC control, multi-chassis expansion and longer distance control. Since a single slot controller costs tens of thousands of dollars, which is several times more expensive than a desktop computer, a desktop computer plus an MXI3 is chosen as the control scheme. Therefore, it is necessary to configure PXI8335, PCI8335 and optical fiber connection cable for communication between the two. (2) Selection of data acquisition card and conditioning module: Since the parameters involved in the integrated test system are very rich, including analog quantities such as temperature, pressure and vibration parameters, as well as digital signal quantities, in some cases the synchronization requirements of signal measurement are relatively high. Therefore, we choose NI's PXI-4472 multi-function data acquisition card and SCXI1121 signal conditioning module. The PXI-4472 multi-function data acquisition card is based on the PXI bus and combines the integrated trigger function of Compact PCI with the Windows operating system. While retaining the structure and function of PCI bus and Compact PCI module, it adds system reference clock and trigger bus, making the PXI system more suitable for building industrial automation measurement and control system. For non-standard output signals, conditioning modules need to be selected. SCXI1121 modules are selected for pressure sensors, temperature sensors, and speed sensors respectively. (3) Selection of network server components: Considering the need for remote data browsing and control via the network, a server, client (for debugging), and hub need to be configured for the system. In the system design, the PC connected to the PXI via MXI3 is used as the server. The PXI host and PXI-4472 multi-function data acquisition card are the core of the entire test system, undertaking tasks such as receiving user commands, data acquisition, waveform display, data storage, and data analysis. 2.2 System Software Structure Software is the soul of a virtual instrument. An efficient software development platform is conducive to building a powerful virtual instrument system. The software design of this integrated test system uses NI's LabVIEW as the development platform. LabVIEW is mainly used in instrument control, data acquisition, data analysis, and other fields. It is a very good virtual instrument development environment. It uses a graphical programming language and has the characteristics of being visual, intuitive, and highly integrated. LabVIEW programs contain a rich function library and integrate communication modules such as GPIB, VXI, RS-232, and RS-485, facilitating modular programming. LabVIEW also has built-in libraries, providing numerous connection mechanisms to link with external program code or software through DLLs, shared libraries, and OLE [2,3]. To achieve scalability and maintainability of the test system software, the software structure needs careful design during the system software design phase, enabling the system software to adapt to new hardware modules and algorithms. A general framework approach is adopted, separating data and the test process to achieve the universality and flexibility of the test software. The configuration parameters of the test instruments and test items are stored in the project configuration file, and the test result data is managed by the database. The task of the test process is to read the data from the configuration file, configure the test instruments, perform corresponding data acquisition, analysis, and calculation, and write the test results to the test result database. After analysis, the system can be structured according to the following functions: (1) Test project configuration: Complete the configuration of the working parameters of the test project. Adopt the structured general design idea, store the hardware parameters, software parameters and some special requirements used in the test process in a configuration file, and store the necessary parameters in the database. When testing, just call the configuration file of each project to complete the corresponding test task. In this way, the operator does not need to have too much knowledge of the system or too much knowledge of computers. Just follow the test process and use the mouse to perform simple operations. The signal analysis system in the integrated test system adopts the modular software programming design idea. Each analysis function is completed by a module. The signal analysis system includes data acquisition and storage, waveform display, parameter measurement and signal analysis, and can ultimately realize the functions of data acquisition, storage, analysis and display. (2) Physical channel calibration: Since the data acquisition card acquires voltage or current signals, it does not directly reflect the magnitude of physical quantities. It needs to go through a conversion process, which is called calibration. For example, if the data collected from the pressure sensor is 100mV, but the actual pressure applied to the sensor is 1MPa, then the calibration result is 10MPa/V. There is a nonlinear error in the actual operation of the system, so it is necessary to consider how to correct it during calibration. This paper uses a nonlinear correction method when implementing this function. (3) System self-test and data acquisition card configuration: Before the system works, it is necessary to ensure that all parts are working properly, so the channels need to be tested and the system needs to be self-tested. Otherwise, if a problem is found later in the experiment, it will be a waste of manpower and time. (4) Data acquisition: This part is the key part of the system and also the most complex part of the system. It includes waveform recording, data storage, real-time data release, simple data processing and many other functions. (5) Data playback: This part is the core of the system. All data analysis and processing are completed in this part. It includes processing result storage, automatic report generation, report printing and other functions. (6) Data Management: Since all test results are required to be stored in the database, the management of test data is actually the management of the test database. The management content includes functions such as test record retrieval. It can be managed locally or on the network. (7) Help: An application software system is not a good system if it does not have a clear and concise help system. By browsing the help, a novice can quickly become proficient in using it. Based on the comprehensive consideration of the system functions, the entire software is divided into the main control module, channel calibration and configuration module, system self-test module, data acquisition module, data playback module, data management module, help module, etc. Each module can be further divided into smaller sub-modules. The relationship between the modules is shown in Figure 2. [align=center] Figure 2 Overall structure of system software[/align] 3 Signal Analysis and Processing [5,6] Data analysis and processing is a key link in the comprehensive test system. There are many methods for analyzing and processing sampled data. They have different functions. In actual engineering testing, it is often necessary to use multiple different methods at the same time to obtain satisfactory results. Therefore, the integrated test system utilizes a signal analysis and processing software package developed using LabVIEW to analyze and process the acquired signals. The main analyses include data preprocessing, time-domain analysis, frequency-domain analysis, and joint time-frequency analysis. The output signals acquired by the sensors are sampled and converted into digital signals by an A/D converter. Before being sent to the analysis and processing system, the sampled signals undergo data preprocessing. The purpose of data preprocessing is to remove noise mixed in the signal as much as possible to improve the signal-to-noise ratio. Data preprocessing covers a wide range, typically including windowing, digital filtering, mean removal, trend extraction, and standardization. Then, the data is analyzed and processed as needed. 4. Implementation of Network Functions To achieve remote measurement and control, we utilize DataSocket technology in virtual instrument technology to connect devices with different functions in different regions, enabling resource sharing and making data acquisition and remote transmission possible. The specific steps are as follows: A single computer on the network is used as a DataSocket Server, i.e., a server, to implement data acquisition and data publishing functions, i.e., as a DataSocket Publisher; other computers connected to the network act as DataSocket Subscribers. The server collects data. At the data sending end, the device number and acquisition channel of the data acquisition card are set, the appropriate number of samples and acquisition speed are selected, and the AI ​​Sample Channel.vi is used to collect signals. The data collected is published to the DataSocket Server using DataSocket Publisher. The client uses DataSocket Subscriber to receive data from the DataSocket Server. The flowchart of the data acquisition and transmission program using DataSocket technology is shown in Figure 3 [4]. In Figure 4, at the data publishing end, the DataSocket Write function is called to write data to the location specified by the URL (uniform resource locator); at the remote client receiving end, the DataSocket Read function is called to read data from the location specified by the URL and restore it to the original data type and send it to the Waveform Graph in the front panel window for display. In this example, the URL specified is "dstp://ni-302aph". At the data sending end and the remote receiving end, the stop button in the While loop can control the termination of data acquisition, data sending and receiving, respectively. [align=center]Figure 3 Flowchart of Data Acquisition Transmitter and Remote Receiver[/align] 5. Summary This paper uses the PXI bus and LabVIEW visual programming software to design a modular, universal, and serialized comprehensive testing system. It features data acquisition, measurement, data storage, data sharing, and data analysis processing functions, enabling it to quickly and effectively reflect various parameter information of the tested system, facilitating status monitoring and fault diagnosis of the tested object. Compared with traditional testing instruments, the comprehensive testing system based on virtual instrument technology has a compact structure, rich functionality, and leverages the flexibility of software design. It replaces multiple instruments with a single computer, offering strong operability, good versatility, high cost-effectiveness, powerful functions, and convenience. Furthermore, it can achieve remote online real-time monitoring. Therefore, this system has broad development and application prospects. 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