An instrument driver, in the context of test and measurement (T&M) application development, is a set of software routines that simplifies remote instrument control. Instrument drivers are specified by the IVI Foundation[1] and define an I/O abstraction layer using the virtual instrument software architecture (VISA). The VISA hardware abstraction layer provides an interface-independent communication channel to T&M instruments. The drivers encapsulate the Standard Commands for Programmable Instruments (SCPI) commands, which are an ASCII-based set of commands for reading and writing instrument settings and measurement data. This standard allows an abstract way of using various programming languages to program remote-control applications instead of using SCPI commands. An instrument driver usually has a well-defined API.
The VXIplug&play Systems Alliance was founded in 1993[2] with the aim of unifying VXI hardware and software to achieve 'plug and play' interoperability for VXI and GPIB instruments. As part of the unifying process, VXIplug&play instrument drivers[3] were also defined.
When the IVI Foundation took over the Alliance in 2002, it defined a new generation of instrument drivers to replace the VXIplug&play standard. The IVI instrument driver specification intends to overcome the drawbacks of VXIplug&play. These IVI (Interchangeable Virtual Instrumentation) drivers[4] are currently defined in three different architectures:
Instrument drivers allow quicker development of remote-control applications for instrumentation. The drivers reduce the difficulty of string formatting when using SCPI commands by providing a well-defined API. The IVI and VXIplug&play Instrument Drivers use the VISA as the hardware abstraction layer so that hardware-independent applications can be developed.
The VISA library allows test and measurement equipment to be connected through various hardware interfaces. The following interfaces are available:
The LAN eXtensions for Instrumentation (LXI) standard defines the communications protocols for controlling test and measurement systems using Ethernet. The standard requires vendors to offer IVI compliant instrument drivers.
