Virtual Instrument Software Architecture
Virtual Instrument Software Architecture, commonly known as VISA, is a widely used I/O API in the test and measurement (T&M) industry for communicating with instruments from a PC. VISA is an industry standard implemented by several T&M companies, such as Rohde & Schwarz, Agilent Technologies, Anritsu, Bustec, National Instruments, Tektronix and Kikusui.
The VISA standard 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 or VXI-11 (over 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 API exposed from Windows DLL, visa32.dll and over the Microsoft COM technology. A VISA.NET implementation is currently (2012) under development by the IVI Foundation. 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.
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.
- Standard Commands for Programmable Instruments (SCPI)
- High Speed LAN Instrument Protocol (HiSLIP)
- Instrument Driver
- "VISA Specification". IVI Foundation.
- "IVI-6.1: High-Speed LAN Instrument Protocol (HiSLIP)". IVI Foundation.
- "VXI-11 Bus Specification". VXI Bus Consortium.
- "USB Test & Measurement Class Specification". USB Implementers Forum Inc.