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14
Chapter 1
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To see the list of drivers registered with the IVI Foundation, go to
http://www.ivifoundation.org
.
Familiarizing Yourself with the Driver
Although the examples in
IVI Getting Started Guide
use a DMM driver, you will
likely
employ a variety of IVI drivers
to develop test programs. To jumpstart that
task, you’ll want to familiarize yourself quickly with drivers you haven’t used before.
Most ADEs provide a way to explore IVI drivers to learn their functionality. In each
chapter, where applicable, we add a note explaining how to view the available
functions. In addition, browsing an IVI driver’s help file often proves an excellent
way to learn its functionality.
Examples
As we noted above, each example chapter in
IVI Getting Started Guide
shows
you how to use an IVI driver to write and run a program that performs a simple
measurement on a simulated instrument and returns the result. The examples
demonstrate common steps using IVI drivers.
Where practical, every example
includes the steps listed below:
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Download and Install the IVI driver– covered in the Download and Install IVI
Drivers section above.
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Determine the VISA address string – Examples in
IVI Getting Started Guide
use the simulate mode, so we chose the address string
GPIB0::23::INSTR,
often shown as GPIB::23. If you need to determine the VISA address string for
your instrument and the ADE does not provide it automatically, use an IO
application, such as National Instruments Measurement and Automation
Explorer (MAX) or Agilent Connection Expert.
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Reference the driver or load driver files – For the examples in this guide, the
driver is the
Agilent 34401A IVI-COM Specific Driver, Version 1.1.0.11,
March 2006 (from Agilent Technologies)
or the
Agilent 34401A IVI-C
Specific driver, Version 4.1, October 2006 (from National Instruments).
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Create an instance of the driver in ADEs that use COM – For the examples in
this guide, the driver is the
Agilent 34401A (IVI-COM) or HP 34401 (IVI-C)
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Write the program:
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Initialize the instrument – Initialize is required when using any IVI driver.
Initialize establishes a communication link with the instrument and must
be called before the program can do anything with the instrument. We set
reset to
true
, ID query to
false
, and simulate to
true
.
Setting reset to true tells the driver to initially reset the instrument.
Setting the ID query to false prevents the driver from verifying that the
connected instrument is the one the driver was written for. Finally,
setting simulate to true tells the driver that it should not attempt to
connect to a physical instrument, but use a simulation of the
instrument.
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Configure the instrument – We set a range of
1.5 volts
and a resolution of
0.001 volts (1 millivolt)
.