Virtual instrument software architecture

Test and measurement API

For other uses of the term visa, see Visa (disambiguation).

Virtual instrument software architecture (VISA) is a widely used application programming interface (API) in the test and measurement (T&M) industry for communicating with instruments from a computer. VISA is an industry standard implemented by several T&M companies, such as, Anritsu, Bustec, Keysight Technologies, Kikusui, National Instruments, Rigol, Rohde & Schwarz, and Tektronix.

The VISA standard[1] includes specifications for communication with resources (usually, but not always, instruments) over T&M-specific I/O interfaces such as GPIB and VXI. There are also some specifications for T&M-specific protocols over PC-standard I/O, such as HiSLIP[2] or VXI-11[3] (over TCP/IP) and USBTMC[4] (over USB).

The VISA library has standardized the presentation of its operations over several software reuse mechanisms, including through a C API exposed from Windows DLL, visa32.dll, over the Microsoft COM technology, and through a .NET API. 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 [specify] are also available for less common programming languages [specify] and software reuse technologies.

## History

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VISA was originally standardized through the VXIplug&play Alliance, a now-defunct T&M standards body. The current standard, "VISA Specification 5.0", is maintained by the IVI Foundation.

## See also

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* Standard Commands for Programmable Instruments (SCPI)
* High Speed LAN Instrument Protocol (HiSLIP)
* Instrument driver

## References

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1. ^ "VISA Specification". IVI Foundation.
2. ^ "IVI-6.1: High-Speed LAN Instrument Protocol (HiSLIP)" (PDF). IVI Foundation.
3. ^ "VXI-11 Bus Specification". VXI Bus Consortium.
4. ^ "USB Test & Measurement Class Specification". USB Implementers Forum Inc. Archived from the original on 2010-03-26. Retrieved 2010-04-30.

## External links

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* Fast Remote Instrument Control with HiSLIP - Application Note
* IVI Foundation Specifications