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DAQ takes advantage of Vista functionality

Posted: 14 May 2007 ?? ?Print Version ?Bookmark and Share

Keywords:Windows Vista? DAQ cards? WOW64 interface?

By Sam Ku
Adlink Technology Inc.

Launched early this year, the Windows Vista OS offered major improvements in areas of performance, security and visual presentation. The Vista OS, codenamed Longhorn during its early development, comes as an opportunity for engineers and scientists to solve critical technical problems and achieve greater, faster data processing not possible on earlier Windows releases.

Key advantages
The new OS from Microsoft offers several new features:

User account control (UAC) - A major enhancement in Windows Vista welcomed by computer scientists and engineers is its improvement in terms of PC security. Windows Vista incorporates UACa new user privilege model designed to prevent virus attacks and illegal software applications from halting or taking control of the system, initiating installation or changing firewall settings.

32bit/64bit editions - Launched in both 32bit or 64bit edition, Windows Vista enables the user to choose the edition based on their computer hardware. For applications intended to run on computers with more than 4Gbyte of RAM, the Windows Vista 64bit edition supports memory-intensive applications including vision acquisition and large-scale data processing that are not possible on a 32bit OS.

NET-based API - In Windows XP, programming is done using the Win32 API. In Windows Vista, .NET Framework 3.0 (formerly called WinFX) interface delivers a straightforward way to program applications on Vista territory. Since programmers have been integrating their software applications using .NET Framework-based code for several years now, they can conveniently integrate and deploy these applications using Windows Vista while keeping their existing hardware.

WOW64 layer
Expecting that 32bit applications will be executed in 64bit version of Windows OS, Microsoft included an abstraction layer called WOW64 (Windows-on-Windows 64bit) on all 64bit releases. WOW64 is a lightweight translation layer subsystem and feature identical interfaces on all 64bit versions of Windows. The primary purpose of WOW64 is to create a 32bit environment that provides the required interfaces for executing 32bit Windows applications in a 64bit system without modifications. Since WOW64 is included on all 64bit versions of Windows, users may enjoy a smooth transition from a 32bit environment to Windows XP and Windows Server 2003 for 64bit Extended Systems. However, even with WOW64, 32bit programs executed on Windows Vista x64 Edition cannot take advantage of the larger 64bit address spaces or wider 64bit registers on 64bit processors.

On a 32bit Windows system, the maximum memory available is 4Gbyte which is shared among the OS, memory-resident drivers, applications and application data. Hence, the maximum memory available to specific applications running on a 32bit OS is 2Gbyte or up to 3Gbyte with a special OS and compiling options. On a 64bit system, the WOW64 infrastructure could allocate as much as 4Gbyte of RAM to a 32bit Windows application without addressing memory space for the OS and drivers. This capability extends a solid 4Gbyte memory allocation for resource-hungry applications and posts a significant increase in computing efficiency.

Adlink is providing both 32bit and 64bit versions of kernel drivers for its full-range of DAQ cards.

Adlink has released three 32bit software libraries that flawlessly run on the 64bit edition of Windows Vista. These include the PCIS-DASK, D2K-DASK and WD-DASK. As these packages conform with the WOW64 interface, integration with a 64bit OS comes automatically and without any need for additional user configuration. However, software drivers that run in the kernel must also be 64bit.

However, users are faced with several conditions to fully obtain the benefits of Windows Vista x64 Edition. Theoretically, application running on Windows Vista x64 Edition should improve performance because of access to larger available memory even when the application is running via the WOW64 layer. It is important to mention that Windows Vista x64 Edition is not necessarily faster than its 32bit counterpart. In some cases, x64 may even perform slower because of the unrelated OS overhead of larger pointer. In actuality, 32bit emulated applicationswhich runs through the WOW64 layercould not address more memory than they could in a 32bit system. The time before Windows Vista x64 Edition gains widespread adoption is also an open issue.

Vista-ready solution
For Windows Vista, Adlink is providing both 32bit and 64bit versions of kernel drivers for its full-range of DAQ cards. As stated, PCIS-DASK, D2K-DASK and WD-DASK also supports Windows XP and Windows Server 2003 for 64bit Extended Systems, including AMD64 and Intel x86-64 system architectures. (PCIS-DASK is Windows Kernel Driver APIs for Adlink NuDAQ PCI/cPCI Series. D2K-DASK is Windows Kernel Driver APIs for Adlink DAQ-2000 and PXI-2000 Series. WD-DASK is Windows Kernel Driver APIs for Adlink PCI/PXI-9820 High-speed digitizer.)

All DASK kernel drivers/libraries provide a common set of API that allows easy access to all the functions of Adlink products. Moreover, these advances in application development enable the users to perform detailed operations and experience superior performance and reliability from their DAQ systems.

Microsoft requires a digital signature on all drivers starting from Windows Vista x64 Edition. By requiring signed drivers, Microsoft aims to reduce failures and improve stability by setting the spotlight on vendor responsibility with regard to driver bugs and glitches. For this reason, all Adlink 64bit DASK drivers are digitally signed for Windows Vista x64 Edition.

Using the WOW64 subsystem, Adlink has also verified on Windows Vista x64 Edition its complete range of ActiveX control sets including PCIS-OCX, D2K-OCX and WD-OCX, as well as DAQBencha 32bit ActiveX controls for measurement and SCADA/HMI.

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