Virtual Instrumentation

What is a virtual instrument and how is it different from a traditional instrument? Virtual instruments are defined by the user while traditional instruments have fixed, vendordefined functionality.

Figure 1. Traditional instruments (left) and software based virtual instruments (right) largely share the same architectural components, but radically different philosophies Every virtual instrument consists of two parts – software and hardware. A virtual instrument typically has a sticker price comparable to and many times less than a similar traditional instrument for the current measurement task. However, the savings compound over time, because virtual instruments are much more flexible when changing measurement tasks. By not using vendor-defined, prepackaged software and hardware, engineers and scientists get maximum user-defined flexibility. A traditional instrument provides them with all software and measurement circuitry packaged into a product with a finite list of fixedfunctionality using the instrument front panel. A virtual instrument provides all the software and hardware needed to accomplish the measurement or control task. In addition, with a virtual instrument, engineers and scientists can customize the acquisition, analysis, storage, sharing, and presentation functionality using productive, powerful software. Here are some examples of this flexibility in practice: 1. One Application -- Different Devices For this particular example, an engineer is developing an application using LabVIEW and an M Series DAQ board on a desktop computer PCI bus in his lab to create a DC voltage and temperature measurement application. After completing the system, he needs to deploy the application to a PXI system on the manufacturing floor to perform the test on new product. Alternatively, he may need the application to be portable, and so he selects NI USB DAQ products for the task. In this example, regardless of the choice, he can use virtual instrumentation in a single program in all three cases with no code change needed.

Figure 2. Upgrading hardware is easy when using the same application for many devices. 2. Many Applications, One Device Consider another engineer, who has just completed a project using her new M Series DAQ device and quadrature encoders to measure motor position. Her next project is to monitor and log the power drawn by the same motor. She can reuse the same M Series DAQ device even though the task is significantly different. All she has to do is develop the new application using virtual instrumentation software. Additionally, both projects could be combined into a single application and run on a single M Series DAQ device, if needed.

Figure 3. Reduce costs by reusing hardware for many applications.

How do virtual instrumentation hardware capabilities compare to traditional instrumentation? An important concept of virtual instrumentation is the strategy that powers the actual virtual instrumentation software and hardware device acceleration. National Instruments focuses on adapting or using high-investment technologies of companies such as Microsoft, Intel, Analog Devices, Xilinx, and others. With software, National Instruments uses the tremendous Microsoft investment in OSs and development tools. For hardware, National Instruments

builds on the Analog Devices investment in A/D converters. Fundamentally, because virtual instrumentation is software-based, if you can digitize it, you can measure it. Therefore, measurement hardware can be viewed on two axes, resolutions (bits) and frequency. Refer to the figure below to see how measurement capabilities of virtual instrumentation hardware compare to traditional instrumentation. The goal for National Instruments is to push the curve out in frequency and resolution and to innovate within the curve.

Figure 4. Compare virtual instrumentation hardware over time to traditional instrumentation.

Are virtual instruments and traditional instruments compatible? Many engineers and scientists have a combination of both virtual and traditional instruments in their labs. In addition, some traditional instruments provide a specialized measurement which the engineer or scientist would prefer to have the vendor define rather than actually defining it themselves. This begs the question, “Are virtual instruments and traditional instruments compatible?” Virtual instruments are compatible with traditional instruments almost without exception. Virtual instrumentation software typically provides libraries for interfacing with common ordinary instrument buses such as GPIB, serial, or Ethernet. In addition to providing libraries, more than 200 instrument vendors have contributed more than 4,000 instrument drivers to National Instruments Instrument Driver Library. Instrument drivers provide a set of high-level, human-readable functions for interfacing with instruments. Each instrument driver is specifically tailored to a particular model of instrument to provide an interface to its unique capabilities. To find an instrument driver or learn how to create one for an instrument, visit ni.com/idnet.

How are virtual instruments and synthetic instruments different? A fundamental trend in the automated test industry is a heavy shift toward software-based test

systems. For example, the United States Department of Defense (DoD) is one of the world’s largest customers of automated test equipment (ATE). In order to reduce the cost of ownership of test systems and increase reuse, the DoD, through the Navy’s NxTest program, has specified that future ATE use an architecture built on modular hardware and reconfigurable software called synthetic instrumentation. The adoption of synthetic instrumentation represents a significant development in the specification of future Military ATE systems, and reflects a fundamental shift as reconfigurable software takes center-stage in future systems. Successful implementation of software-based test systems, such as synthetic instrumentation, requires an understanding of the hardware platforms and software tools in the market, as well as an understanding of the distinction between system-level architectures and instrument-level architectures. The Synthetic Instrument Working Group defines synthetic instruments as “a reconfigurable system that links a series of elemental hardware and software components with standardized interfaces to generate signals or make measurements using numeric processing techniques”. This shares many properties with virtual instrumentation, which is “a software-defined system, where software based on user requirements defines the functionality of generic measurement hardware”. Both definitions share the common properties of software-defined instrumentation running on commercial hardware. By moving the measurement functionality into user-accessible reconfigurable hardware, those adopting such architectures benefit by achieving greater flexibility and reconfigurability of systems, which in turn increases performance capabilities while reducing cost.

Virtual Instrumentation for Test Test has been a long-proven field for virtual instrumentation. More than 25,000 companies (the majority being test and measurement companies) use National Instruments virtual instrumentation. Now, companies quickly are adopting up to 200 MS/s digitization capabilities. The PXI consortium hosts more than 60 members delivering hundreds of

products. And tens of thousands of R&D, validation, and product test engineers and scientists literally use thousands and thousands of instrument drivers. Still, the need for test has never been greater. As the pace of innovation has increased, so too has the pressure to get new, differentiated products to market quickly. Consumer expectations continue to increase; in electronics markets, for example, disparate function integration is required in a small space and at a low cost. The economic downturn of recent years has not curbed the need to innovate, but instead has added the restraint of fewer resources. Meeting these demands is a factor in business success – the company that can meet these demands quickly, consistently, and most reliably has a decided advantage over the competition. All of these conditions drive new validation, verification, and manufacturing test needs. A test platform that can keep pace with this innovation is not optional, it is essential. The platform must include rapid test development tools adaptable enough to be used throughout the product development flow. The need to get products to market quickly and manufacture them efficiently requires high-throughput test. To test the complex multifunction products that consumers demand requires precise, synchronized measurement capabilities. And as companies incorporate innovations to differentiate their products, test systems must quickly adapt to test the new features. Virtual instrumentation is an innovative solution to these challenges. It combines rapid development software and modular, flexible hardware to create user-defined test systems. Virtual instrumentation delivers: •

Intuitive software tools for rapid test development;

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Fast, precise modular I/O based on innovative commercial technologies

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A PC-based platform with integrated synchronization for high accuracy and throughput

An example of recent National Instruments innovation accelerating test, control and design is FPGA-based hardware programmed using LabVIEW FPGA. If an engineer needs a new hardware capability, like onboard DSP, or a new triggering mode, you can drill down even further to define this capability in the same software and deploy it to an on-board FPGA. Engineers and scientists have always been able to use LabVIEW to create highly integrated user-defined systems using modular I/O but they can now extend custom configurability to the hardware itself. This degree of user-configurability and transparency will change the way engineers build test systems.

Figure 1. LabVIEW offers user-defined instruments and customizable hardware To learn more about virtual instrumentation and other essential technologies for test, visit ni.com/modularinstruments.

Virtual Instrumentation for Industrial I/O and Control PCs and PLCs both play an important role in control and industrial applications. PCs bring greater software flexibility and capability, while PLCs deliver outstanding ruggedness and reliability. But as control needs become more complex, there is a recognized need to accelerate the capabilities while retaining the ruggedness and reliabilities. Independent industry experts have recognized the need for tools that can meet the increasing need for more complex, dynamic, adaptive, and algorithm-based control. The PAC is the industry’s request and virtual instrumentation’s answer. An independent research firm defined programmable automation controllers (PACs) to address the problem. Craig Resnick of ARC Research defines PAC as: 1. Multidomain functionality (logic, motion, drives, and process) – the concept supports multiple I/O types. Logic, motion, and other function integration is a requirement for increasingly complex control approaches 2. A single multidiscipline development platform – a singular development environment must be capable of supporting varying I/O and control schemes 3. Software tools for designing applications across several machines or process units – the software tools must scale to distributed operation 4. A group of de facto network and language standards – the technology has to take

advantage of common and often high-investment technologies 5. Open, modular architectures – the design and technology specifications must be open, modular, and combinable in implementation PACs deliver PC software flexibility with PLC ruggedness and reliability. LabVIEW software and rugged, real-time, control hardware platforms are ideal for creating a PAC.

To learn more about virtual instrumentation and programmable automation controllers, visit ni.com/pac.

Virtual Instrumentation for Design The same design engineers that use a wide variety of software design tools must use hardware to test prototypes. Commonly, there is no good interface between the design phase and testing/validation phase, which means that the design usually must go through a completion phase and enter a testing/validation phase. Issues discovered in the testing phase require a design-phase reiteration.

[+] Enlarge Image Figure 2. Test plays a critical role in the design and manufacture of today’s electronic devices. In reality, the development process has two very distinct and separate stages – design and test are two individual entities. On the design side, EDA tool vendors undergo tremendous pressure to interoperate from the increasing semiconductor design and manufacturing group complexity requirements. Engineers and scientists are demanding the capability to reuse designs from one tool in other tools as products go from schematic design to simulation to physical layout. Similarly, test system development is evolving toward a modular approach. The gap between these two worlds has traditionally been neglected, first noticeable in the new product prototype stage. Traditionally, this is the stage where the product designer uses benchtop instruments to sanity-check the physical prototypes against their design for correctness. The designer makes these measurements manually, probing circuits and looking at the signals on instruments for problems or performance limitations. As designs iterate through this build-measure-tweak-rebuild process, the designer needs the same measurements again. In addition, these measurements can be complex – requiring frequency, amplitude, and temperature sweeps with data collected and analyzed throughout. Because these engineers focus on design tools, they are reluctant to invest in learning to automate their testing. Systems with intrinsic-integration properties are easily extensible and adapt to increasing product functionality. When new tests are required, engineers simply add new modules to the platform to make the measurements. Virtual instrumentation software flexibility and virtual instrumentation hardware modularity make virtual instruments a necessity to accelerate the development cycle.

What is virtual instrumentation? With virtual instrumentation, software based on user requirements defines general-purpose measurement and control hardware functionality. Virtual instrumentation combines mainstream commercial technologies, such as the PC, with flexible software and a wide variety of measurement and control hardware, so engineers and scientists can create user-

defined systems that meet their exact application needs. With virtual instrumentation, engineers and scientists reduce development time, design higher quality products, and lower their design costs.

Figure 1. Virtual instrumentation combines productive software, modular I/O, and scalable platforms. National Instruments introduced virtual instrumentation more than 25 years ago, changing the way engineers and scientists measure and automate the world around them. In 2004, National Instruments sold more than 6 million channels of virtual instrumentation in 90 countries. Today, virtual instrumentation has reached mainstream acceptance and is used in thousands of applications around the world in industries from automotive, to consumer electronics, to oil and gas.

Why is virtual instrumentation necessary? Virtual instrumentation is necessary because it delivers instrumentation with the rapid adaptability required for today’s concept, product, and process design, development, and delivery. Only with virtual instrumentation can engineers and scientists create the userdefined 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 a modern cell phone. Most 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. The increased functionality of advanced electronics increased functionality is possible because devices have become more software centric. Engineers and scientists can add new functions to the device without changing the hardware, resulting in improved concepts and products without costly hardware redevelopment. This extends product life and usefulness and reduces product delivery times. Engineers and scientists can improve functionality through software instead of developing further specific electronics to do a particular job. However, this increase in functionality comes with a price. Upgraded functionality introduces the possibility of unforeseen interaction or error. So, just as device-level software helps rapidly develop and extend functionality, design and test instrumentation also must adapt to

verify the improvements. The only way to meet these demands is to use test and control architectures that are also software centric. Because virtual instrumentation uses highly productive software, modular I/O, and commercial platforms, it is uniquely positioned to keep pace with the required new idea and product development rate. 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 development. 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 software use of to accelerate 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.

Why has virtual instrumentation been so successful? Virtual instrumentation achieved mainstream adoption by providing a new model for building measurement and automation systems. Keys to its success include rapid PC advancement; explosive low-cost, high-performance data converter (semiconductor) development; and system design software emergence. These factors make virtual instrumentation systems accessible to a very broad base of users. PC performance, in particular, has increased more than 10,000X over the past 20 years. Virtual instruments takes advantage of this PC performance increase by analyzing measurements and solving new application challenges with each new-generation PC processor, hard drive, display, and I/O bus. These rapid advancements, combined with the general trend that technical and computer literacy starts early in school, contribute to successful computer-based virtual instrumentation adoption.

Figure 2. A 10,000x performance increase for PCs helps drive virtual instrumentation system performance. Another virtual instrumentation driver is the proliferation of high-performance, low-cost analog-to-digital (ADC) and digital-to-analog (DAC) converters. Applications such as wireless communication and high-definition video impact these technologies relentlessly. While traditional proprietary converter technology tends to move slowly, commercial semiconductor technologies tend to follow Moore’s law – doubling performance every 18 months. Virtual instrumentation hardware uses these widely available semiconductors to deliver high-performance measurement front ends. Finally, system design software that provides an intuitive interface for designing custom instrumentation systems furthers virtual instrumentation. LabVIEW is an example of such software. The LabVIEW graphical development environment offers the performance and flexibility of a programming language, as well as high-level functionality and configuration utilities designed specifically for measurement and automation applications.

Figure 3. Sample Code Developed in the LabVIEW Graphical Development Environment.

What makes National Instruments a leader in virtual instrumentation? In one word, the answer is software. Software that enables engineers and scientists to create user-defined instruments. At the heart of any virtual instrument is flexible software, and National Instruments invented

one of the world’s best virtual instrumentation software platforms – LabVIEW. LabVIEW is a powerful graphical development environment for signal acquisition, measurement analysis, and data presentation, giving the flexibility of a programming language without the complexity of traditional development tools. Since 1986, when National Instruments introduced LabVIEW for the Macintosh, it has quickly and consistently attracted engineers and scientists looking for a productive, powerful programming language to use in test, control and design applications. Today, LabVIEW is the preferred graphical development environment for thousands of engineers and scientists. For engineers who prefer text-based programming, National Instruments also offers LabWindows/CVI, an application development environment for ANSI C, as well as tools for virtual instrument development using Visual Studio .NET, Measurement Studio.

Figure 4. LabVIEW is a leader in application software used in PC-based data acquisition and instrument control. While software is the heart of every virtual instrument, almost every virtual instrument requires measurement hardware to accurately acquire the measurement. Independent of the programming environment chosen, virtual instrumentation software must provide excellent integration with system measurement hardware. National Instruments software, including LabVIEW, offers open connectivity to tens of thousands of sensors, cameras, actuators, cameras, traditional instruments and plug-in devices (USB, PCI, etc.) from thousands of third-party hardware vendors. In 2004, National Instruments measurement hardware provided customers with more than 6,000,000 virtual instrumentation measurement channels. From low-cost USB data acquisition, to process control vision systems and image acquisition, to RF measurements at 2.7 GHz, to GPIB bus communication, National Instruments has shown more than 25,000 companies that it offers the measurement hardware and scalable hardware platforms required to complete virtual instruments.

What makes National Instruments different from other virtual instrumentation companies? National Instruments has been a virtual instrumentation leader for more than 25 years. This

leadership has grown and been sustained through constant and consistent innovation. Because National Instruments invented and innovated the premier virtual instrumentation graphical development environment, LabVIEW, it attracts thousands of engineers and scientists building virtual instruments. By understanding customer project development needs, National Instruments has consistently delivered significant software innovations, including Express technology, the LabVIEW Real-Time Module and LabVIEW PDA Module, and SignalExpress: 1. Express technology National Instruments created Express technology for LabVIEW, LabWindow/CVI, and Measurement Studio in 2003 to reduce code complexity while preserving power and functionality. Today, more than 50 percent of data acquisition customers use DAQ Assistant to simplify data acquisition tasks. 2. The LabVIEW Real-Time Module and LabVIEW PDA Modules National Instruments extended LabVIEW for deterministic execution using the LabVIEW Real-Time Module and developed matching hardware platforms to make embedded application deployment a reality. The LabVIEW PDA Module extended virtual instrumentation and the LabVIEW platform to handheld devices. 3. NI SignalExpress Design and test engineers asked National Instruments for virtual instrumentation software that interactively measures and analyzes data. In response, National Instruments created SignalExpress – a drag-and-drop, no-programming-required environment ideal for exploratory measurements. In addition to the strong software differentiator, National Instruments offers the most broad and innovative I/O selection among virtual instrumentation companies. To help engineers and scientists meet accelerating demands, National Instruments constantly releases products to further extend breadth. A few recent examples of NI hardware innovation include USB DAQ devices, M Series DAQ devices, and National Instruments CompactRIO: 1. USB DAQ Devices In a recent survey, 70 percent of National Instruments data acquisition (DAQ) customers said they plan to purchase multifunction USB DAQ in the near future. That month, National Instruments released the USB-6008, setting a new low price point for multifunction DAQ at $145 (US). 2. M Series DAQ Devices National Instruments helped establish leadership in plug-in data acquisition when it released the M Series DAQ products in late 2004. The first 18-bit PCI devices, first PCI data acquisition devices with six DMA channels for maximum throughput, and a patent-pending device calibration scheme are just a few of the features that set these products apart. 3. CompactRIO Reconfigurable Control and I/O One of the most innovative additions to National Instruments I/O products is CompactRIO. With an FPGA chip at the heart of this I/O platform, engineers can create custom hardware and customize it repeatedly using LabVIEW FPGA.

Who uses National Instruments virtual instrumentation? National Instruments customers include engineers, scientists, and technical professionals in a wide range of industries. From testing DVD recorders to researching advanced medicines,

they use National Instruments software and hardware to develop user-defined instruments and deliver a diverse set of products and services, faster and at a lower cost. Here are a few examples of how customers use National Instruments virtual instrumentation products: 1. AP Racing – Building Formula 1 Caliper and Brake Test Dynamometers For more than 30 years, AP Racing has been a world leader in brake caliper and race clutch technology and manufacturing. AP Racing concluded that a unique new dynamometer would be a distinct advantage, and virtual instrumentation using National Instruments DAQ devices and LabVIEW provided the flexibility it needed to innovate in the marketplace. 2. Lexmark – Ink Cartridge Electrical Test Ed Coleman, with Lexmark International, Inc., said, “As we continue to adapt our test systems to meet our latest requirements with minimal development time with the use of PCbased modular instruments and industry-standard software. Upgrading to the NI 5122, NI 6552, and LabVIEW 7 Express, we increased the quality of our products and production yields while increasing our test performance with minimal development expense.” 3. Texas Instruments – RF and Wireless Component Characterization With close to $4 billion in revenue, Texas Instruments (TI) is one of the leading wireless IC providers. To streamline its characterization process, TI created test development, management, and automation software powered by NI TestStand and LabVIEW. Using NI products, it expanded its business without sacrificing quality and resources. 4. Drivven – Motorcycle Engine Control Unit (ECU) Prototype In past projects, Drivven spent at least two man-years and $500,000US to develop ECU prototyping systems from custom hardware. For this project, the equipment costs (including the motorcycle and CompactRIO) totaled $15,000US, and development time took approximately three man-months. FPGA-based reconfigurable hardware, CompactRIO, and the LabVIEW Real-Time Module delivered reliability and precise timing resources, and the system was rugged enough to withstand the high-temperature and high-vibration operating environment.

The 3 Layers of Virtual Instrumentation Software Virtual instrumentation software can be divided into several different layers. 1. Application Software: Most people think immediately of the application software

layer. This is the primary development environment for building an application. It includes software such as LabVIEW, LabWindows/CVI (ANSI C), Measurement Studio (Visual Studio programming languages), SignalExpress, and VI Logger. 2. Test and Data Management Software: Above the application software layer the test

executive and data management software layer. This layer of software incorporates all of the functionality developed by the application layer and provides system-wide data management.

3. Measurement and Control Services Software: The last layer is often overlooked, yet

critical to maintaining software development productivity. The measurement and control services layer includes drivers, such as NI-DAQmx, which communicate with all of the hardware. It must access and preserve the hardware functions and performance. It also must be interoperable –it has to work with all other drivers and the many modular I/O types that can be a part of the solution.

Figure 1. Virtual Instrumentation Software

What makes LabVIEW ideal for virtual instrumentation? LabVIEW is an integral part of virtual instrumentation because it provides an easy-to-use application development environment designed specifically for engineers and scientists. LabVIEW offers powerful features that make is easy to connect to a wide variety of hardware and other software. This ease of use and these features deliver the required flexibility for a virtual instrumentation software development environment. The result is a user-defined interface and user-defined application functionality. One of the most powerful features that LabVIEW offers is its graphical programming paradigm. With LabVIEW, engineers and scientists can design custom virtual instruments by creating a graphical user interface on the computer screen through which they: •

Operate the instrumentation program

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Control selected hardware

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Analyze acquired data

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Display results

They can customize the LabVIEW user interface, or front panel, with knobs, buttons, dials, and graphs to emulate traditional instrument control panels of, create custom test panels, or visually represent process control and operation.

Figure 2. LabVIEW virtual instruments include the user interface and application logic. Determine virtual instrument behavior by connecting icons to create block diagrams, which are natural design notations for scientists and engineers. With graphical programming, engineers and scientists can develop systems more rapidly than with conventional programming languages, while retaining the power and flexibility needed to create a variety of applications. LabVIEW is an open environment that includes ready-to-use libraries for everything from serial, Ethernet, and GPIB communication to motion control, data acquisition, and image acquisition.

How does virtual instrumentation take advantage of the latest software trends? Traditional instrumentation solutions, by nature of their fixed packaging and vendor-defined nature, can’t rapidly adapt to new software technologies. Because of its inherent flexibility, virtual instrumentation is much better suited to incorporating new tools and technology – users can simply upgrade their software, rather than purchase a new system. Over the 20+ years of its development, LabVIEW has tightly integrated cutting edge software technology while still providing a seamless transition from version to version. With the long project lifetimes often found in the test and measurement industry, it’s critical that LabVIEW provide a stable platform for development over many decades. However, to ensure maximum productivity of its users, LabVIEW must also take advantage of new technologies as they arise. Many software packages get caught in the trap of rapid adoption of new technology without regard to longevity. For example, software packages based primarily on the Microsoft platform of technology over the past 15 years have had several instances where their software

had to be totally redefined due to the discontinuity of the latest technology, such as COM, ActiveX, and most recently, .NET. LabVIEW has always incorporated and continues to incorporate these technologies to ensure that the user has access to the latest tools, but integrates them in such a way that there is no need to completely rework existing code. New technologies, such as .NET, can simply be added in to existing applications as needed.

What is measurement and control services software? Measurement and control services software is equivalent to the I/O driver software layer. However, it is much more than just drivers. Though often overlooked, it is one of the most crucial elements of rapid application development. This software connects the virtual instrumentation software and the hardware for measurement and control. It includes intuitive application programming interfaces, instrument drivers, configuration tools, I/O assistants, and other software included with the purchase of National Instruments hardware. National Instruments measurement and control services software offers optimized integration with both National Instruments hardware and National Instruments application development environments. As an example, National Instruments raised the bar for data acquisition software when it introduced NI-DAQmx for the Windows OS and increased the ease, speed, and power with which scientists and engineers take measurements. NI-DAQmx leverages several technologies that legacy drivers do not exhibit including multithreading, simplified application programming interface (API), interactive configuration, and intelligent multidevice synchronization. Additionally, NI-DAQmx supports broad ranges of programming languages, devices, buses, sensors, and even mixed signal types. With NI-DAQmx, a new user to data acquisition can easily create an application that leverages parallel processing and synchronizes multiple devices all with interactive, configuration-based programming. In addition to new technologies, every copy of NI-DAQmx ships with a collection of measurement services designed to save data acquisition system developers time and money. This collection of measurement services, in addition to NI-DAQmx, offer more software value than any other data acquisition vendor provides with a DAQ device. A few of these measurement services include, Measurement & Automation Explorer (MAX) for configuring, interacting with, and testing your hardware; DAQ Assistant for configuration-based creation of data acquisition tasks; and VI Logger Lite, FREE software specifically designed for data logging.

[+] Enlarge Image Table 1. NI-DAQmx includes a high-performance driver and additional software to increase productivity.

What are capabilities of virtual instrumentation hardware? An important concept of virtual instrumentation is the strategy that powers the actual virtual instrumentation software and hardware device acceleration. National Instruments focuses on adapting or using high-investment technologies of companies such as Microsoft, Intel, Analog Devices, Xilinx, and others. With software, National Instruments uses the tremendous

Microsoft investment in OSs and development tools. For hardware, National Instruments builds on the Analog Devices investment in A/D converters. Fundamentally, because virtual instrumentation is software-based, if you can digitize it, you can measure it. Therefore, measurement hardware can be viewed on two axes, resolutions (bits) and frequency. Refer to the figure below to see how measurement capabilities of virtual instrumentation hardware compare to traditional instrumentation. The goal for National Instruments is to push the curve out in frequency and resolution and to innovate within the curve.

Figure 1. Compare virtual instrumentation hardware over time to traditional instrumentation. See Also: Learn about NI data acquisition hardware Learn about NI modular instrumentation hardware

On which hardware I/O and platforms does virtual instrumentation software run? National Instruments modular I/O covers diverse I/O types so that engineers and scientists can select I/O across many categories including analog, digital, counter/timer, image, and motion. Modular I/O also includes modular instruments such as oscilloscopes, meters, arbitrary function generators, LCR meters, and more. With the wide variety of excellent I/O, engineers can randomly select any I/O type required by the application. Careful engineering ensures that these diverse I/O types work seamlessly together, meaning they can efficiently share backplane and timing resources. Standard hardware platforms that house the I/O are important to I/O modularity. Laptop and desktop computers provide an excellent platform where virtual instrumentation can make the most of existing standards such as the USB, PCI, Ethernet, and PCMCIA buses. Using these standard buses, National Instruments can focus on measurement hardware innovation while benefiting from inevitable PC platform innovation (for example, USB 2.0 and PCI Express).

Figure 2. Modular I/O and scalable platforms such as USB, PCI, and PXI provide flexibility and scalability. In addition to supporting standard platforms, National Instruments is part of a 65-vendor consortium that has helped tailor the PXI hardware platform for virtual instrumentation. PXI is a standard for modular I/O built on PC technologies. It adds integrated timing and synchronization, industrial ruggedness, and increased channel count to a PC-based architecture. Today, there are more than 1000 products created for the PXI platform being used worldwide by thousands of companies. Choosing the appropriate platform on which to create virtual instrumentation on depends on specific application requirements. For example, portability, stringent synchronization, and acquisition rates all play a role in choosing a platform.

[+] Enlarge Image Table 1. National Instruments Hardware Platform Comparison See Also: Learn about the PXI hardware platform Learn about the USB hardware platform Learn about the Compact FieldPoint hardware platform Learn about the CompactRIO hardware platform

How will new bus technologies such as USB 2.0 and PCI Express enhance virtual instrumentation? Virtual instrumentation uses advances in commercially available computer technologies to make faster and higher-performance measurements at lower cost than traditional instruments. One example of this is with PC data buses. While instrument communication interfaces such as serial and GPIB have remained virtually unchanged for decades, new PC buses provide dramatic improvements in bandwidth and ease of use. Since the mid-1960s, PC processing power has, according to Moore’s Law, approximately doubled every 18 months. Now, data buses such as PCI Express and USB 2.0 are making similar leaps in speed. Good virtual instrumentation software takes advantage of these new technologies while minimizing the impact on the application. The 132 MB/s bandwidth provided by the 32-bit, 33MHz PCI bus still present on most desktop PCs was a good match for plug-in peripherals 10 years ago, but now can be monopolized by a single device, such as a Serial-ATA drive. And Gigabit LAN cards – at 1000 Mb/s – use approximately 95 percent of available PCI bandwidth. PCI bus architecture requires it to share the available 132 MB/s with all devices on the bus, so high-bandwidth devices such as Serial-ATA drives and Gigabit LAN cards strangle other devices on the PCI bus. To remedy these limitations, a new peripheral bus called PCI Express has recently started to appear in new PCs. PCI Express maintains software compatibility with PCI, but replaces the physical bus with a high-speed (2.5 Gb/s) serial bus. Data is sent in packets through transmit and receive signal pairs called lanes with about 200 MB/s bandwidth per direction, per lane. Multiple lanes can be grouped together into x1 (“by-one”), x2, x4, and x8 lane widths. Unlike PCI, which shares bandwidth between all devices on the bus, this bandwidth is provided to each device in the system. PCI Express benefits for virtual instrumentation are obvious. Plug-in devices such as data acquisition devices and frame grabbers can use the increased bandwidth for faster acquisitions and higher throughputs, and multiple system devices benefit from guaranteed bandwidth availability.

Figure 3. The Evolution of PC Bus Technologies USB 2.0, now standard on all new desktop and laptop PCs, also offers significant benefits to virtual instrumentation. Initially created to connect peripherals such as keyboards and mice to the PC, USB has quickly become the ubiquitous standard for sending data to and from the PC

and electronic devices, including digital cameras, MP3 players, and even data acquisition devices. The USB plug-and-play nature makes usability and device portability extremely simple. The PC automatically detects when a new device has been plugged in, queries for device identification, and appropriately configures the required drivers. In addition, USB is hot-pluggable, so, unlike other data buses, there is no need to power down the PC before adding or removing a device. The high speed of USB 2.0 improves data throughput by 40X compared to USB 1.1, increasing bandwidth to 480 Mb/s. All new PCs come with USB 2.0 ports, and PCI Express is emerging as the new plug-in bus standard. As Intel, Dell, HP, and other vendors continue to develop systems and components based on these technologies, economies of scale continue to improve performance and costs. Virtual instrumentation and National Instruments products will continue to use these bus technology advances to provide higher speed test and measurements products at even lower prices.

What are the benefits of Ethernet for virtual instrumentation? Virtual instrumentation systems frequently use Ethernet for remote test system control, distributed I/O, and enterprise data sharing. The primary benefit in using Ethernet is cost. In nearly all cases, the Ethernet network preceded the measurement system, so it often adds little cost to the measurement system itself. Ethernet provides a low-cost, moderate-throughput method for exchanging data and control commands over distances. However, due to its packet-based architecture, Ethernet is not deterministic and has relatively high latency. For some applications, such as instrumentation systems, the lack of determinism and high latency make Ethernet a poor choice for integrating adjacent I/O modules. These situations are better served with a dedicated bus such as PXI, VXI, or GPIB. Often, a virtual instrumentation system uses other buses in conjunction with Ethernet. Typically, a network node consists of modular I/O clusters. Each cluster uses a high-speed, low-latency bus to exchange data between different I/O modules. To communicate with neighboring nodes, transfer data to a remote location, or accept commands from a remote location, the network nodes use the Ethernet network.

Figure 4. Example of Ethernet/LAN based virtual instrumentation system