Understanding Instrument Programming Terminology

1. VISA

    VISA (Virtual Instrument Software Architecture) — The VISA standard was developed by the VXIplug&Play Foundation. Drivers that conform to the VXIplug&Play standard always perform I/O through the VISA library. Therefore, if you use plug&play drivers, you need the VISA I/O library. The VISA standard was intended to provide a similar set of function calls for a variety of physical interfaces. However, in practice, the VISA library prefers specialized vendor interfaces.

2. VISA - COM

     The VISA-COM library is a COM interface used by I/O and was developed as a companion specification to VISA. VISA-COM I/O provides VISA services in a COM-based API. VISA-COM includes some high-level services not available in VISA, but in terms of low-level I/O communication capabilities, VISA-COM is a
subset of VISA. Agilent VISA-COM is used by IVI component drivers, which require the installation of Agilent VISA.

3. VXI Plug and Play

    A hardware and software standard that allows interchangeability between VXI instruments produced by different manufacturers. For more information, see  http://www.vxipnp.org

4. XML

    XML (Extensible Markup Language) — A subset of SGML that constitutes a text-specific markup language for interchange of structured data. The Unicode standard is the reference character set for XML.

5. ActiveX 

    A standard way of wrapping COM-compliant software modules so that they can be used in standard PC applications. ActiveX controls can be used in any ActiveX-compliant application, regardless of where they are built.

6.ADE

    ADE (Application Development Environment) — An integrated set of software development programs. An ADE may include a text editor, compiler, debugger, and other tools used in building, maintaining, and debugging applications. An example of an ADE is Microsoft Visual Studio. [page]

7. API

    API (Application Programming Interface) — IVI Drivers An API is a set of tightly defined software routines that allows an application to access functions and services provided by an underlying operating system or library. An example of an API is an IVI driver.

8. C#

    C# (pronounced "C sharp") — A C-like, component-oriented language that eliminates many of the difficulties associated with C/C++.

9.COM

    See Microsoft COM.

10.Direct I/O

    Direct I/O — Sends commands directly to the instrument without the benefit and intrusion of a driver. SCPI Example: SENSe:VOLTage:RANGe:AUTO

11. Driver (or instrument driver)

    A collection of functions resident on a computer for controlling external devices.

12.DLL

    DLL (Dynamic Link Library) — An executable program or data file that is bundled with an application and is loaded only when needed, thus reducing memory requirements. The functions or data in a DLL can be shared by several applications at the same time.

13.IDE

    IDE (Integrated Development Environment) —See ADE.

14.I/O layer

    Input/output (I/O) layer – Software that collects data from and issues commands to peripherals. The VISA library is an example of an I/O layer that allows applications and drivers to access peripheral instruments.

15.IVI
    IVI (Interchangeable Virtual Instrument) - A standard instrument driver model defined by the IVI Foundation ( http://www.ivifoundation.org ) that allows engineers to switch instruments produced by different manufacturers without rewriting code.

16.IVI COM

    IVI COM Driver (also called IVI Component Driver) — IVI COM stands for IVI Driver as a COM Object. You get all the intelligence and benefits of the development environment because IVI COM is a smarter, easier, and more consistent way to send commands to instruments. It is similar for multiple instruments.

17. Library

    Files contain reusable software operations or functions that can be used by other programs. They may be C-based libraries, Visual Basic libraries, .NET libraries, COM libraries, or libraries based on other software technologies.

18.Microsoft COM

    Microsoft COM (Component Object Model) — The concept of software components is similar to that of hardware components: as long as the components have the same interface and perform the same function, they are interchangeable. Software components are a natural extension of DLLs. Microsoft developed the COM standard to allow software companies to build new software components that can be used with existing applications without having to re-build the applications. This capability makes test and measurement instruments and their COM-based IVI component drivers interchangeable.

19.NET Framework

    The .NET Framework is an object-oriented API that simplifies application development in the Windows environment. The .NET Framework has two main components: the common language runtime and the .NET Framework class library. New frameworks can be added by anyone.

20. Plug and Play Driver

    Also called generic instrument driver. An important category of specialized drivers. Plug and Play driver standards were originally developed for VXI instruments, hence the name VXI Plug and Play standards. These standards have also been adopted by non-VXI instruments, hence the name "Plug and Play" drivers. Library functions are in accessible
C language source that can be called from programs written in VEE, BASIC, VIEW, or LabWindows/CVI.

21.SCPI

    SCPI (Standard Commands for Programmable Instruments) — SCPI defines a set of standard commands for controlling programmable test and measurement devices in instrumentation systems.
See the “Direct I/O” example at http://www.scpiconsortium.org .

22. Universal Driver

    Another name for a Plug and Play driver.