Virtual Instruments: Create user-defined

As technology advances and time to market shorten, engineers and scientists are required to respond more quickly and efficiently to industry challenges. The development of the concept of virtual instrumentation is a product of the increasing popularity of computers and the increasing competitiveness of industry and research. This article explains the concept of virtual instrumentation and its advantages in terms of increased productivity, accuracy and performance.

Virtual instruments mainly consist of computers equipped with powerful application software, cost-effective hardware such as PC plug-and-play boards and driver software, which can provide more powerful functions in test and automatic control than traditional instruments. Virtual instruments represent a fundamental shift from traditional hardware-based instrument systems to software-based systems, which can fully utilize the powerful computing power, productivity, display capabilities and connectivity capabilities of modern computers. Although computer and integrated circuit technology have made great progress in the past two decades, it is software that builds virtual instruments on these powerful hardware architectures and provides better innovation methods and greatly reduces costs. Engineers and scientists can use virtual instruments to build test and automatic control systems that can fully meet their requirements (user-defined) without being restricted by traditional fixed-function instruments (vendor-defined).

Comparison with Traditional Instruments

Single, stand-alone traditional instruments such as oscilloscopes and waveform generators are very powerful but expensive and are designed to perform specific tasks defined by one or more vendors. They are generally not expandable or customizable by users. The knobs, buttons, built-in circuits, and functions available to users on the instruments are very well defined. In addition, many specialized techniques and expensive components must be used to develop these instruments, so these traditional instruments are very expensive and slow to become popular.

Computer-based virtual instruments have the advantage of being able to take full advantage of the latest technologies integrated into existing computers. These technological and performance advantages include powerful processors such as P4, operating systems and technologies such as Microsoft Windows XP, .NET, and Apple Mac OS X. In addition to integrating powerful performance, these platforms also make it easy to access powerful tools such as the Internet. Traditional instruments also often lack portability, while virtual instruments running on laptops automatically integrate portability.

For engineers and scientists whose requirements, applications, and needs change very quickly, great flexibility is needed to create their own solutions. They can use virtual instruments to meet their specific requirements without replacing the entire device because a variety of application software and plug-and-play hardware installed on the computer are everywhere. The flexibility of defining systems in a modular way allows engineers and scientists to truly move away from expensive vendor-defined systems.

Using virtual instrument solutions can reduce capital expenses, system development costs, and system maintenance costs while accelerating time to market and improving the quality of their own products. Virtual instruments allow users to pay for what they "need" rather than what they passively "get" from vendor-defined systems. Software

in Virtual Instruments

Software is the most important component of virtual instruments. Engineers and scientists can effectively create their own applications by designing and integrating the routines required for a specific process through appropriate software tools. They can also create the right user interface that fully meets the application's purpose and interactive use requirements. They can define how and when the application software obtains data from the device, how to process or analyze the data, manage and store the data, and present the results to the user. They

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

Virtual instruments are not limited to a single computer. In fact, with the recent boom in network technology and the Internet, it will become more and more common for instruments to use powerful interconnection functions to distribute tasks. Typical examples include supercomputers, distributed monitoring and control equipment, and data or result visualization from different geographical locations.

National Instruments (NI), as a pioneer in virtual instruments, launched the graphical programming environment LabVIEW. LabVIEW provides an easy-to-use application development environment specifically designed to meet the needs of engineers and scientists, and is an integral part of virtual instruments.

Figure 1. LabVIEW virtual instrument front panel

Graphical Programming

The graphical programming environment is one of the powerful features that LabVIEW provides to engineers and scientists. Users can use LabVIEW to customize virtual instruments and create a graphical user interface on the computer screen. Through this interface, they can operate instrument programs, control selected hardware, analyze captured data, and display results.

Users can also customize the panel of the virtual instrument with components such as knobs, buttons, dialers, and graphics to simulate the control panel of traditional instruments, create customized test panels, or express control and operation processes in a visual way. The similarity between standard flow charts and graphical programs shortens the learning process associated with traditional text-based languages. [page]

Connecting icons together to create a block diagram determines the behavior of the virtual instrument, which is also a natural design concept for scientists and engineers. Graphical programming can develop systems faster than traditional programming while retaining the functionality and flexibility required to create a variety of different applications.

Virtual instruments have great advantages in all stages of the engineering process, from research and design to manufacturing testing.

During the research and design stages, engineers and scientists need rapid development and prototyping capabilities. With virtual instruments, you can quickly develop programs, test prototypes, and analyze results on the same instrument in a fraction of the time it takes to test with traditional instruments.

Research and development (R&D) applications require seamless integration of software and hardware. Whether you need to connect to a stand-alone instrument via GPIB or send signals directly to the computer through a data capture board and signal conditioning hardware, LabVIEW makes it easy to connect the hardware and software. Using virtual instruments, you can automate the test process, eliminate possible manual errors, and ensure consistent results because no unknown or unexpected changes will be introduced.

Development Testing and Usability

The flexibility and power of virtual instruments make it easy to build complex test processes. For automated design verification testing, users can build test routines in LabVIEW and integrate with test management software such as TestStand, which has powerful test management capabilities.

Reducing test time and simplifying the development of test processes are fundamental efforts in manufacturing test, and virtual instruments provide the high performance to 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 stringent throughput requirements. NI's TestStand can easily manage test sequences, test execution, and test reports based on routines written in LabVIEW.

Figure 2. LabVIEW virtual instrument block diagram

Manufacturing applications require software that is reliable, high-performance, and interoperable. Virtual instruments offer all of these benefits, integrating features such as alarms, historical data trending, security, networking, industrial I/O, and enterprise interconnect. These capabilities allow users to easily connect to many types of industrial devices, such as PLCs, industrial networks, distributed I/O, and plug-in data capture boards.

Virtual instruments are more than just personal computers

Commercial PC technology has recently begun to migrate to embedded systems, such as Windows CE for embedded development, Intel x86-based processors, PCI and CompactPCI buses, and Ethernet technology. Virtual instruments also use commercial technology to achieve cost and performance advantages, which are also adding embedded and real-time capabilities. For example, LabVIEW runs on Linux or, for special embedded targets, on the embedded ETS real-time operating system from VenturCom. If virtual instruments are used as a scalable framework that can be extended from desktops to embedded devices, then virtual instruments should be considered as one of the tools in the complete toolbox of embedded system developers.

The technology change that has significantly affected embedded system development is networking and the Web. Ethernet has become the standard network architecture used by companies around the world. In addition, the popularity of Web interfaces in the PC field has also spread to cell phones, PDAs, and now industrial data capture and control system development.

Because virtual instrument software can use cross-platform compilation technology to integrate desktop and real-time systems in one development environment, users can now take advantage of the built-in Web server and easy-to-use network functions of desktop software and port it to real-time and embedded systems. For example, you can use LabVIEW to simply configure the built-in Web server and export the application interface on Windows to a defined secure machine on the network, and then download the application through the interface and run it on the dumb embedded system in the handheld. The entire process does not require additional programming required by embedded systems.

Embedded system development is one of the fastest growing engineering fields and will continue to grow in the foreseeable future as consumers demand smarter cars, facilities, home appliances, and more. These commercial technology innovations will strongly promote the popularity of virtual instruments. Leading companies that provide virtual instrument software and hardware tools need to invest more in professional technology and product development to better serve this field. For example, for NI's flagship product, LabVIEW, the virtual instrument software platform, NI describes the development prospects as follows: from development for desktop operating systems to embedded real-time systems, to handheld personal digital assistants, to FPGA-based hardware, and even to smart sensors.

A series of virtual instrument concepts, such as integrated hardware and software, flexible modular tools, and the use of commercial technologies, together form an infrastructure on which engineers or scientists can quickly complete their system development and maintain it for a long time. Because virtual instruments 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 article

Virtual instruments use increasingly advanced computer technology to create user-defined systems based on open architectures. This concept not only ensures that users stay away from vendor-defined systems, but also ensures that today's systems can be smoothly upgraded to meet tomorrow's needs .