Virtual Instrumentation
Virtual instrumentation combines mainstream commercial technologies, such as the PC, with flexible software and a wide variety of measurement and control hardware. Engineers use virtual instrumentation to bring the power of flexible software and PC technology to test, control and design applications making accurate analog and digital measurements. Engineers and scientists can create user-defined systems that meet their exact application needs. Industries with automated processes, such as chemical or manufacturing plants use virtual instrumentation with the goal of improving system productivity, reliability, safety, optimization, and stability. Virtual instrumentation is computer software that a user would employ to develop a computerized test and measurement system for controlling from a computer desktop, an external measurement hardware device, and for displaying, test or measurement data collected by the external device on instrument-like panels on a computer screen. It extends to computerized systems for controlling processes based on data collected and processed by a computerized instrumentation system. The front panel control function of the existing instrument is duplicated through the computer interface. The application ranges from simple laboratory experiments to large automation application.
Virtual instrumentation as shown in Figure 1.10 uses highly productive software, modular I/O and commercial platforms. National Instruments LabVIEW, a premier virtual instrumentation graphical development environment, uses symbolic or graphical representations to speed up development. The software symbolically represents functions. Consolidating functions within rapidly deployed graphical blocks further speeds up development.
Figure: Virtual instrumentation combines productive software, modular I/O and scalable platforms.
Another virtual instrumentation component is modular I/O, designed to be rapidly combined in any order or quantity to ensure that virtual instrumentation can both monitor and control any development aspect. Using well-designed software drivers for modular I/O, engineers and scientists quickly can access functions during concurrent operation.
The third virtual instrumentation element using commercial platforms, often enhanced with accurate synchronization, ensures that virtual instrumentation takes advantage of the very latest computer capabilities and data transfer technologies. This element delivers virtual instrumentation on a long-term technology base that scales with the high investments made in processors, buses and more.
In summary, as innovation mandates use of software to accelerate a new concept and product development, it also requires instrumentation to rapidly adapt to new functionality. Because virtual instrumentation applies software, modular I/O and commercial platforms, it delivers instrumentation capabilities uniquely qualified to keep pace with today’s concept and product development.
Virtual Instrument and Traditional Instrument
A traditional instrument is designed to collect data from an environment, or from a unit under test, and to display information to a user based on the collected data. Such an instrument may employ a transducer to sense changes in a physical parameter such as temperature or pressure, and to convert the sensed information into electrical signals such as voltage or frequency variations. The term “instrument” may also cover a physical or software device that performs an analysis on data acquired from another instrument and then outputs the processed data to display or recording means. This second category of instruments includes oscilloscopes, spectrum analyzers and digital millimeters. The types of source data collected and analyzed by instruments may thus vary widely, including both physical parameters such as temperature, pressure, distance, light and sound frequencies and amplitudes, and also electrical parameters including voltage, current and frequency.
A virtual instrument (VI) is defined as an industry-standard computer equipped with user-friendly application software, cost-effective hardware and driver software that together perform the functions of traditional instruments. Simulated physical instruments are called virtual instruments (VIs). Virtual instrumentation software based on user requirements defines general-purpose measurement and control hardware functionality. With virtual instrumentation, engineers and scientists reduce development time, design higher quality products, and lower their design costs. In test, measurement and control, engineers have used virtual instrumentation to downsize automated test equipment (ATE) while experiencing up to a several times increase in productivity gains at a fraction of the cost of traditional instrument solutions.
Virtual instrumentation is necessary because it is flexible. It delivers instrumentation with the rapid adaptability required for today’s concept, product and process design, development and delivery. Only with virtual instrumentation, engineers and scientists can create the user-defined instruments required to keep up with the world’s demands. To meet the ever-increasing demand to innovate and deliver ideas and products faster, scientists and engineers are turning to advanced electronics, processors and software. Consider modern cell phones. Most of them contain the latest features of the last generation, including audio, a phone book and text messaging capabilities. New versions include a camera, MP3 player, and Bluetooth networking and Internet browsing.
Virtual instruments are defined by the user while traditional instruments have fixed vendor-defined functionality. In a conventional instrument, the set of components that comprise the instrument is fixed and permanently associated with each other. Nevertheless, there is some software that understands these associations. Thus the primary difference between a virtual instrument and a conventional instrument is merely that the associations within a virtual instrument are not fixed but rather managed by software.
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