Overview of Virtual Instrument
Source: Shangpin China |
Type: website encyclopedia |
Time: June 16, 2014
The traditional real face instrument is mainly composed of three functional blocks: signal acquisition and control unit, signal analysis and processing unit, result expression and output unit. Because these function blocks basically exist in the form of hardware or solidified software. The product has been set before delivery. Therefore, the traditional instrument is complex in design and poor in flexibility. There is no mode of independent use and manual operation. Its function is limited to simply imitate the steps of manual operation, and it can be used in more complex and continent trial comparisons internet It's inconvenient to get up. With the rapid development of computer technology, integrated circuit technology and communication technology, great changes have taken place in the field of instrument technology. In the mid-1980s, National Instruments took the lead in proposing the concept of virtual instrument based on computer technology, bringing the virtual side test technology into a new development period. Subsequently, it developed and launched the virtual instrument VI (Virtual Instrumentation) based on a variety of bus systems. 1.1.1 Concept of virtual instrument intestine Virtual instrument vi is a new type of device only system formed by the intervention of computer technology in the instrument lock city. It is a computer instrument system designed and defined by the user himself on the hardware platform with the general computer as the core. From the virtual operation panel, the side test function is realized by the test software. In the virtual instrument, the computer is at the core position, and the computer system and instrument system are organically integrated into a whole, so that the structure concept and design view of the instrument have undergone a mutation. From the perspective of composition, virtual instrument is a high-end and low-cost new instrument that uses computer equipment and corresponding hardware and special software to form both the four functions of ordinary instruments and the special functions that ordinary instruments do not have. From the application point of view, the simulation instrument uses the powerful graphical environment of the computer. Establish a friendly virtual instrument panel (i.e. front panel). The operator controls the operation of the instrument through a friendly graphical interface and graphical programming language to complete signal acquisition, analysis, judgment, display, storage and data generation. Figure 1 shows the front panel of a virtual DC digital voltmeter designed with LabVIEW. 1.1.2 Development, characteristics and advantages of virtual instruments Along with the rapid development of Hui electronic technology, computer technology and network technology, and the application of electronic testing dogs. The volume conversion instrument has made continuous progress. Digital instruments, intelligent instruments and simulation instruments have successively appeared. At the same time, it has gradually developed from a single instrument to a full plus instrument system, virtual instrument system, etc. The development and application of virtual instrument technology was sent to Lab VIEW designed by NI Company in 1986. This is an integrated development environment for the development, debugging and program of Kuiyu graphics, realizing the concept of virtual instrument. NI also put forward the concept of "The software is the instrument", which fully reflects that the role of software in virtual instrument is extremely difficult. Its appearance enables users to define instruments themselves, design instrument systems flexibly and meet diversified practical needs. With the development of virtual instrument software development platform and hardware, the development cycle of the continent test system based on virtual instrument is shortened, the cost is reduced, the test speed, accuracy and reusability are improved, and it is easier to maintain and expand. In 1997, NI Company introduced a new instrument bus standard - PXI bus standard. The PXI bus mode is formed by adding mature technical specifications and requirements to the PCI general practice core technology, adding the reference clock of the multi board synchronous trigger bus, which is suitable for the star trigger bus with precise timing, so as to be used as the local bus for high-speed communication of adjacent modules. In 1998, a group of manufacturers producing PC data acquisition products should establish the "Open Data Acquisition Association. ODAA" and publish the "Open Data Acquisition Standard. ODAS". The ultimate goal of this standard is to make PC data acquisition software and hardware produced by different manufacturers have extensive interchangeability. One of the standards related to WAS is Interchangeable Virtual Instruments. This is a new technology developed from VXI plug&play technology. Instruments in the continent test system can be replaced without changing software. That is to say, IVI oscilloscope driver general sub all IVI compatible oscilloscopes, regardless of the manufacturer or test platform. VXI instrument has recently appeared the construction scheme of sub module in the module, that is, several miniaturized modules are installed on the original module pin, so as to make more effective use of the calibration block space and further improve the flexibility of instrument construction. In the past two years, the software and hardware technologies that constitute the virtual instrument system have made new development, especially the sensor technology, the acquisition kernel technology, and the software platform technology have developed rapidly. For example, the IEEE 1344-VXI external controller interface has the advantages of high data transfer rate (400 Mbits) and low cost: GPIB - Universal Shenhang Bus (USB) controller also provides enhanced performance for instrument control. In a word, virtual instrument is a kind of instrument with more functions. It is a huge change in the traditional instrument concept and will represent an important direction of the future development of instruments. In the virtual instrument system, hardware is only to solve the problem of signal input and output, and software is the key of the whole system. Users can easily change, increase or decrease the function and scale of the instrument system by modifying the software, so there is a saying that "software is an instrument". The appearance of virtual instrument technology has completely broken the mode that traditional instruments are only defined by manufacturers and cannot be changed by users. Virtual instrument technology gives users a space to give full play to their talents and imagination. Users (not manufacturers) can design their own instrument systems according to their own needs to meet a variety of application needs. Compared with traditional instruments, virtual instruments have the following characteristics and advantages. (1) The concept of "universal" function of traditional instruments is broken, and the signal analysis, display, storage, printing and other management are centralized to the computer for processing. Due to the full use of computer technology, the performance of data transmission and exchange has been completed, which makes the construction of the system more flexible and simple. (2) It emphasizes the new concept of "software is an instrument". Software has played a role in the instrument response that was previously realized by hardware or even the whole machine. Because of the reduction of many discrete chess simulation hardware that may move deeply over time and need regular calibration, and the use of standardized bus, the system's lateral accuracy, lateral speed and repeatability have been greatly improved. Because the virtual instrument is equipped with sensing and reflecting devices of vision, hearing, touch and motion, according to the psychological and physiological characteristics of human vision and hearing, the computer generates realistic three-dimensional images, so that people can obtain a variety of perceptual effects, thus achieving the feeling of being in the scene. (3) The instrument is defined by the user himself. The function and scale of the system can be modified, increased or decreased through software. It can be easily connected with peripherals, networks and other applications, improving the interactivity of the instrument. Virtual instrument provides users with reusable code base for creating instruments by themselves, and handles functions such as communication, timing, and triggering between chess pieces. It emphasizes that on the basis of the writing of general computer platform, through software and soft panel, traditional instruments defined by manufacturers are transformed into user defined special instruments composed of computer software and several chess pieces. The appearance of virtual instrument has completely broken the traditional way that the instrument volume is defined by the manufacturer and cannot be changed by users, giving users a space to give full play to their ability and imagination. (4) The openness of virtual instruments and the modularization of functional software enable users to unify the design, use and management of instruments to the standards of virtual instruments, improve the reuse rate of resources, shorten the time for system establishment, and make the functions easy to expand and manage in a standardized manner. The cost of production, maintenance and development of software and hardware is reduced by using the toilet. Virtual instrument can not only be used as a single digital side test instrument, but also form a more complex side test system, and even form a distributed side test system through high-speed computer network for remote monitoring and fault diagnosis. In addition, using the virtual instrument system based on the software architecture instead of the traditional instrument system based on the hardware architecture can also greatly save the purchase and maintenance costs of the instrument. It can be seen that compared with traditional instruments, virtual instruments have obvious technical advantages in terms of intelligence, processing capacity, performance price ratio, operability, etc. There are many advantages that traditional instruments cannot match, which makes the application of virtual instruments very extensive. Table 1-1 shows the comparison between virtual instruments and traditional instruments.
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