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With the latest version of the Windows OS, Windows 7, LabVIEW users can unlock new technologies.
Instead of adding significantly new or different functionality in Windows, Microsoft improved many of the features introduced in Windows Vista, refined the usability of the shell, and increased the system responsiveness and performance. These changes, combined with a focus on hardware and software compatibility, make Windows 7 a strong candidate for the latest test and measurement applications. This article will explain how applications written within the NI LabVIEW graphical development environment can take advantage of Windows 7 and the latest computing platforms to increase data throughput, improve performance, and take advantage of technologies such as 64-bit, USB data acquisition (DAQ), and PCI Express.
Increasing Throughput with NI USB DAQ and Windows 7
Commercial vendors are already shipping computers with Windows 7. These computers offer the same benefits in overall performance and multiple cores as well as provide the latest bus technologies, including multiple PCI Express and Hi-Speed USB slots.
Microsoft has invested significantly in USB improvements for Windows 7. These improvements, such as the elimination of unnecessary timers, selective hub suspension, and lower enumeration time for USB flash devices, increase the performance of USB test and measurement devices. In recent benchmark testing, the new NI CompactDAQ chassis obtained a 10 percent increase in overall attainable bandwidth with Windows 7, compared to the same hardware running on Windows XP. The increased hardware performance, combined with the multicore optimization of both the Windows 7 OS and LabVIEW software, resulted in a performance increase of up to 20 percent during high-speed or multifunction I/O measurements.
Figure 1. Due to several improved features, the Windows 7 OS is
a reliable program for measurement applications written with LabVIEW software.
High-Performance Measurements with PXI Express and Multicore
Microsoft has restructured much of Windows 7 to perform more system tasks concurrently in order to benefit from increasingly common multicore processors. A key example is the Microsoft rearchitecture of the graphics device interface (GDI), which was designed to improve responsiveness when multiple applications are running simultaneously. This rearchitecture results in fewer sequential obstacles, which can provide a more responsive user interface and better overall system performance of multithreaded measurement applications.
Multithreaded software assigns independent, asynchronous processes to separate threads, which can be executed in parallel by separate computer cores. Computer processors are no longer getting faster; instead, the processor manufacturers are adding more cores onto a single chip. For LabVIEW programmers, it is common to create multiple computationally intensive tasks in a single application that can run in parallel; this is as simple as drawing two loops on a block diagram. LabVIEW and NI drivers, such as NI-DAQmx, are multithreaded, which helps test engineers easily create high-performance acquisition and analysis applications without manually spawning and managing separate threads. DAQ applications written in LabVIEW and use NI hardware on a multicore computer benefit from the improvements in Windows 7 and are designed to further optimize the use of multicore processors.
Measurements that require high throughput and fast performance are prompting engineers to use new technologies such as multicore processors and PXI Express to meet increasing demands for speed. The new NI X Series DAQ devices natively support PCI Express and PXI Express, which offer dedicated bidirectional bandwidth of up to 250 MB/s. NI also offers many additional PXI Express modular instruments for high-precision, high-frequency measurements. Engineers can use these technologies with Windows 7, which supports the latest buses and improves support for multicore processing to remove restrictions and improve data throughput of their measurement applications.
Figure 2. Benchmarks performed with NI CompactDAQ revealed as much as a 20 percent increase in data throughput on Windows 7.
Understanding the Difference Between 32-Bit and 64-Bit Versions of Windows 7
Windows 7 is the third Microsoft OS to support 64-bit processors. Although 32-bit versions of Windows continue to be the most popular and offer the most native compatibility with applications, 64-bit hardware and software are available. When upgrading to Windows 7, it is important to be aware of the potential benefits and considerations of 64-bit versus 32-bit in order to select the appropriate platform.
The new 64-bit version of LabVIEW 2009, which is available for download from ni.com, is the first version of LabVIEW to offer native compatibility with 64-bit operating systems (Vista and Windows 7 only). Measurement applications that run natively on 64-bit hardware and software can take advantage of a larger amount of physical memory than 32-bit systems, which is beneficial for applications that are processing large amounts of contiguous data. Access to additional memory can easily increase system performance by eliminating the need to swap processes in and out of page files on hard drives, which are much slower than physical memory and cache. Along with increased physical memory, additional registers on a 64-bit processor can increase execution speed of applications by as much as 20 percent, depending on how the code is written. However, only LabVIEW 2009 core software, the NI Vision Development Module, and most NI drivers offer native support for a 64-bit version of Windows. Non-native support for 32-bit versions of applications is made possible by an emulation later known as Windows on Windows (WoW); however, this does adversely impact execution speed and performance.
Test and measurement applications created to analyze large data sets, which are synonymous with high-channel-count systems and fast sampling rates, may benefit from the switch to a 64-bit version of Windows 7. However, a majority of LabVIEW applications will not inherently benefit from switching to 64-bit versions.
Figure 3. With Windows 7, the performance of a LabVIEW application with four parallel loops on a quad-core machine experienced as much as a 10 percent performance increase compared to Windows XP.
The Microsoft OS Support Life Cycle
The introduction of Windows 7 is especially relevant given that Microsoft officially discontinued sales of Windows XP in June 2008. Windows XP, which was released more than nine years ago, continues to be the most popular OS on the market. A recent survey of National Instruments customers indicates that more than 80 percent of their test and measurement applications are still running on Windows XP, while less than 10 percent have adopted Windows Vista. Now that Windows 7 is available, customers have the opportunity to upgrade older PC measurement hardware to take advantage of the latest multicore processors and bus technologies including PCI Express, which provides higher throughput and increases overall system performance.
Ensuring Hardware and Software Compatibility
Microsoft has clearly indicated that Windows Vista device drivers work correctly on Windows 7 and that the company is not introducing any new compatibility requirements to the driver model. This policy is designed to avoid the same incompatibility problems users experienced when Windows Vista first debuted. (Many common devices did not work or would not install.)
In addition to the compatibility mode option, which helps applications “think” they are running in an older version of Windows, Microsoft is turning to new virtualization technologies in the Windows 7 Professional and Ultimate versions to eliminate the risk that software cannot run on Windows 7. With a new Windows 7 mode, known as Windows XP Mode, users can emulate the popular Windows XP OS. This may present LabVIEW programmers with the easiest possible mechanism for running older applications.
NI Product Compatibility
With early access to Windows 7, National Instruments has already ensured that the majority of NI application software, including LabVIEW 2009, LabVIEW SignalExpress 2009, and DIAdem 11.1 SP1 – as well as the November version of the NI Device Drivers DVD – already supports Windows 7. Additionally, NI is committed to releasing Windows 7 support for NI LabWindows™/CVI, Measurement Studio, and NI TestStand before the end of 2009. Customers interested in transitioning their measurement and automation systems to Windows 7 in order to take advantage of the new productivity and performance benefits can upgrade today.
Elijah Kerry is a product manager for LabVIEW at National Instruments, focusing on large, mission-critical development applications and software engineering practices. He holds a bachelor’s degree in computer engineering from the University of Missouri, Columbia.
This article will appear in the Q4 2009 issue of Instrumentation Newsletter, available on November 13, 2009.
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