Virtual instrument software architecture: Difference between revisions

Revision as of 17:28, 22 May 2009

Revision as of 05:03, 24 May 2009

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'''Virtual Instrument Software Architecture''', commonly known as '''VISA''', is a widely used [[Input/output|I/O]] [[Application programming interface|API]] in the Test & Measurement industry for communicating with [[Measuring instrument|instruments]] from a [[Personal computer|PC.]] VISA is an [[industry standard]] implemented by several T&M (Test & Measurement) companies, such as [[Agilent|Agilent Technologies ]] and [[National Instruments|National Instruments. ]]

The VISA standard includes specifications for communication with resources (usually, but not always, instruments) over T&M(Test and Measurement)-specific I/O interfaces such as [[GPIB]] and [[VXI|VXI. ]] There are also some specifications for T&M-specific [[Protocol (computing)|protocols]] over PC-standard I/O, such as VXI-11 (over [[TCPIP|TCP/IP]] ) and USBTMC (over [[USB]]).

The VISA library has standardized the presentation of its operations over several software reuse mechanisms, including through a C [[Application programming interface|API]] exposed from Windows [[Library (computer science)#Dynamic linking|DLL,]] visa32.dll and over the Microsoft [[Component Object Model|COM]] technology. Although there are several VISA vendors and implementations, applications written against VISA are (nominally) vendor-interchangeable thanks to the standardization of VISA's presentation and operations/capabilities. Implementations from specific vendors are also available for less common programming languages and software reuse technologies.

=== History ===

VISA was originally standardized through the VXI plug&play Alliance, a now-defunct T&M standards body. The current standard, "VISA Specification 3.0", is maintained by the [http://www.ivifoundation.org IVI Foundation.]