Creating user definitions based on the most popula

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Virtual instrument: create user definitions based on open architecture

with the development of technology and the shortening of time to market, engineers and scientists are required to respond more quickly and efficiently to industry challenges. The development of the concept of virtual instrument is the product of the increasing popularity of computers and the increasing competitiveness of industry and research fields. This paper describes the concept of virtual instrument and its advantages in improving productivity, accuracy and performance

virtual instruments are mainly composed of computers equipped with powerful application software, cost-effective hardware such as PC plug and play board and driving software, which can provide stronger functions than traditional instruments in terms of testing and automatic control. Virtual instrument represents the fundamental transfer from traditional hardware based instrument system to software based system. It can give full play to the powerful computing power, production capacity, display capacity and connection capacity of modern computers. Although computer and integrated circuit technology have made great progress in the past two decades, it is software that has built virtual instruments on these powerful hardware architectures and provided better innovation methods, which has greatly reduced the cost. Engineers and scientists can use virtual instruments to build (user-defined) test and automatic control systems that can fully meet their requirements, instead of being limited by traditional fixed function instruments (supplier defined)

comparison with traditional instruments

single independent traditional instruments such as oscilloscope and waveform generator have very powerful functions, but they are also expensive. They are mainly designed to perform special tasks defined by one or more suppliers. Users generally cannot extend or customize. The knobs, buttons, built-in circuits and functions available to users on the instrument are very clear. In addition, many professional technologies and expensive components must be used to develop these instruments. Therefore, these traditional instruments are very expensive and the popularization speed is relatively slow

the computer-based virtual instrument has the advantage of making full use of the latest technology integrated in the existing computer. These technical and performance advantages include powerful processors such as P4, Microsoft Windows XP Net and Apple Mac OS X. In addition to the powerful performance of integration, these platforms are also very easy to access powerful tools such as Internet. Traditional instruments often lack portability, while virtual instruments running on laptops automatically integrate portability

for engineers and scientists whose requirements, applications and requirements change very quickly, they need a lot of flexibility to create their own solutions. They can use virtual instruments to meet their special requirements, and do not need to replace the entire device, because a variety of application software and plug and play hardware installed on the computer are everywhere. The flexibility to define systems in a modular manner allows engineers and scientists to truly move away from expensive vendor defined systems

the use of virtual instrument solutions can reduce capital costs, system development costs and system maintenance costs, while speeding up the time to market and improving the quality of their own products. Virtual instruments allow users to pay for their "needs" instead of passively "what they get" from a supplier defined system

software in virtual instrument

software is the most important part of virtual instrument. Engineers and scientists can effectively create their own applications by designing and integrating the routines required for a particular process with appropriate software tools. They can also create correct user interfaces that can fully meet the application purpose and interactive use requirements. They can define how and when applications get data from devices, how to process or analyze data, manage and store data, and present results to users

they can also use powerful software to create intelligence and decision-making capabilities in the instrument. Another important advantage of software is its modularity. When dealing with large projects, engineers and scientists can divide the whole project into several functional units that are easier to solve. These subtasks will be easier to manage and test, thus reducing the possibility of unexpected behavior

virtual instrument is not limited to an independent computer. In fact, with the rapid development of network technology and Internet, it will be more and more common for instruments to use powerful interconnection functions for task allocation. Typical examples include supercomputers, distributed monitoring and control devices, and visualization of data or results from different geographical locations

as a pioneer of virtual instruments, National Instrument Corporation (Ni) launched the graphical programming environment LabVIEW. LabVIEW provides an easy-to-use application development environment specially designed to meet the needs of engineers and scientists. It is an integral part of virtual instrument integration

figure 1 LabVIEW virtual instrument front panel

graphical programming

graphical programming environment is one of the powerful capabilities provided by LabVIEW to engineers and scientists. Users can use LabVIEW to customize the design of virtual instruments, create a graphical user interface on the computer screen, and operate the instrument program, control the selected hardware, analyze the captured data and display the results through this interface

users can also customize the panel of virtual instruments with knobs, keys, dialers, graphics and other components to simulate the control panel of traditional instruments, create a test panel whose distance is the track width of two wheels on the front axle, or express the control and operation process in a visual way. The similarity between standard flow charts and graphical programs shortens the learning process associated with traditional text-based languages

connecting icons together to create a block diagram can determine the behavior of virtual instruments, which is also a natural design concept of scientists and engineers. Through graphical programming, the system can be developed faster than traditional programming, while retaining the function and flexibility required to create a variety of different applications, often changing test samples

virtual instrument has great advantages in all stages of the engineering process (from research, design to manufacturing and testing)

in the research and design phase, engineers and scientists need rapid development and prototyping capabilities. The virtual instrument can be used to quickly develop programs, test prototypes and analyze results on the same instrument, and the time required is only a small part of the traditional instrument testing time

r&d applications require seamless integration of software and hardware. Whether it is necessary to connect with an independent instrument through GPIB or not, and whether it is necessary to directly send the signal to the computer through data capture board and signal conditioning hardware, LabVIEW can easily connect the software and hardware. The use of virtual instruments can automate the testing process, eliminate possible manual errors, and ensure the consistency of results because it will not cause unknown or unexpected changes

development testing and usability

complex testing processes can be easily established by using the flexibility and powerful functions of virtual instruments. For automatic design verification testing, users can establish test routines in LabVIEW and integrate them with test management software, such as TestStand with powerful test management functions

reducing test time and simplifying the development of test process are the most basic goals in manufacturing test, and the high performance provided by virtual instrument can meet these requirements. These PC based tools have high-speed, multi-threaded engines that can run multiple test sequences in parallel, so they can fully meet the strict throughput requirements. TestStand of Ni company can easily manage test sequence, test execution and test report based on the routines written in LabVIEW

figure 2 LabVIEW virtual instrument block diagram

manufacturing applications require that the software must be reliable, high-performance and interoperable. Virtual instrument has all these advantages. It integrates performance such as alarm, historical data trends, security, group, industrial i/o and enterprise interconnection. Users can use these functions to easily connect many types of industrial equipment, such as PLC, industrial network, distributed i/o and plug-in data capture board

virtual instruments are more than personal computers

recently, commercial PC technology has begun to transfer to embedded systems, such as Windows CE for embedded development, Intel X86 based processors, PCI and CompactPCI bus and Ethernet technology. In order to reflect the advantages of cost and performance, virtual instruments also use commercial technologies, which are also adding embedded and real-time functions. For example, LabVIEW can run on Linux or the embedded ETS real-time operating system provided by venturcom for special embedded targets. If virtual instrument is used as a scalable framework to extend from desktop to embedded devices, virtual instrument should be regarded as one of the tools in the complete toolbox of embedded system developers

the technical changes that significantly affect the development of embedded systems are network and web. Ethernet has become the standard network architecture used by companies all over the world. In addition, the popularity of web interface in PC field has also spread to the development of cellular, PDA and current industrial data acquisition and control systems

since virtual instrument software can integrate desktop and real-time systems into one development environment by using cross platform compilation technology, users can now take advantage of the easy-to-use network functions of built-in web server and desktop software and migrate it to real-time and embedded systems. For example, you can use LabVIEW to simply configure the built-in web server, output the application interface on windows to the security machine defined on the network, and then download the application through this interface and run it on the fool embedded system in the handset. The whole process does not require additional programming required by the embedded system

embedded system development is one of the fastest growing engineering fields The large diameter extensometer is not flexible enough to move up and down, and will continue to develop in the foreseeable future, because consumers need smarter cars, facilities, household equipment, etc. The innovation of these commercial technologies will effectively promote the popularization of virtual instruments. Leading enterprises providing virtual instrument software and hardware tools need to increase investment in professional technology and product development to better serve this field. For example, for the virtual instrument software platform LabVIEW, the flagship product of Ni, the development prospect described by Ni company is as follows: from the development of desktop operating systems to embedded real-time systems, to handheld personal digital assistants, to FPGA based hardware, and even to intelligent sensors

a series of virtual instrument concepts, such as integrated software and hardware, flexible modular tools, and the use of commercial technology, together form an infrastructure, in which engineers or scientists can quickly complete their system development and maintain it for a long time. Because virtual instrument can provide many options and functions in embedded development, it is very helpful for embedded developers to understand and read these tools

summary of this paper

virtual instrument adopts more and more advanced computer technology, and can create a user-defined system on the basis of open architecture, which will cause local stress concentration. This concept not only ensures that users stay away from supplier definitions

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