VISA Drivers for Test Instruments
- details of the VISA drivers for test instruments, the accompanying standards, what they are and how to use them.
VISA test instrument drivers are widely used in many areas of the electronics test industry.
VISA drivers enable many test instruments to be programmed without the need for referring to low level instructions.
As a result these drivers enable swifter, more convenient and also more accurate programming on test instruments within an automated test environment.
In view of their advantages test drivers are widely used and VISA ones have become an industry standard.
The VISA or Virtual Instrument Software Architecture test driver standard was originally devised by the VXO Plug and Play Systems Alliance (www.vxipnp.org). However the VISA standard has now been updated to include PXI support.
Then in 2002, the VXI Plug & Play Systems Alliance voted to become part of the IVI Foundation, with the merger taking place in 2003.
This means that all updates to the VISA standard are now undertaken by the IVI Foundation.
VISA driver advantagesThe use of the VISA test instrument driver standard offers developers many advantages. Some of these advantages are listed below.
- The use of VISA enables a common standardised I/O layer to be used for all I/O functions.
- By having a common I/O later, it allows instruments from different manufacturers to be operated on the same bus without conflicts.
- IT provides a common and defined method of writing drivers and thereby standardising and simplifying driver writing and use.
- The VISA standard uses defined data types and in some cases defined function name's. This simplifies programming.
- The use of VISA instrument driver standards speeds up programming and reduces programming errors because new instruments follow the same interface rules.
Basics of VISA driversThe VISA standard includes details of the specifications that need to be used for communicating with what are termed resources over the I/O interface. Originally this was VXI but this has now been expanded to PXI, and GPIB may also be used on occasions. Typically the resources are the test instruments.
By Ian Poole
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