Technical data

138 Agilent Connectivity Guide
6 Programming Your Instruments
Addressing Instruments
This section gives guidelines to address instruments, including:
• Addressing Instruments via GPIB
• Addressing Instruments via USB
• Addressing Instruments via LAN
To simplify the addressing in your programs, you can use VISA aliases.
A VISA alias is a name of your choosing, which you assign to a device
and use in your programs. Once assigned, the alias is a synonym for the
device's VISA address, so you can use it to open a VISA session (using
the viOpen function) and to get resource information (using
viParseRsrc or viParseRsrcEx).
Agilent Connection Expert allows you to define VISA aliases for the
devices in your test system.
Why use VISA aliases? Using VISA aliases in your programs, rather
than actual VISA addresses, provides two significant advantages:
• Portability. If you program using aliases, you can run your
program on a new test system, whose instruments are at different
addresses, simply by using Connection Expert to create the same
aliases on the new system as you created on your development
system. Similarly, you can move or replace instruments without
changing or recompiling test code, simply by changing the alias
definitions in Connection Expert.
NOTE
This chapter discusses addressing for VISA and VISA COM. This form
of addressing is also used with IVI-COM and VXIplug&play instrument
drivers. This chapter also includes some discussion of SICL addressing.
For a full discussion of SICL addressing, see the Agilent SICL User’s
Guide. For a discussion of addressing for the Agilent 488 API, see the
Agilent 488 Online Help. Both of these documents are available from
the IO Control’s Documentation menu.