User`s guide

Agilent VISA User’s Guide 153
resource (or resource instance)
In VISA, an implementation of a resource class (in
object- oriented terms, an instance of a resource class).
For example, an instrument is represented by a resource
instance.
resource class
The definition of a particular resource type (a class in
object- oriented terms). For example, the VISA Instrument
Control resource classes define how to create a resource
to control a particular capability of a device.
resource descriptor
A string, such as a VISA resource descriptor, that
specifies the I/O address of a device.
SCPI
Standard Commands for Programmable Instrumentation: a
standard set of commands, defined by the SCPI
Consortium, to control programmable test and
measurement devices in instrumentation systems.
secondary VISA
A VISA installation that does not install visa32.dll in the
standard VISA location. The secondary VISA installation
names its VISA DLL with a different name (agvisa32.dll)
so that it can be accessed programmatically. The primary
VISA will be used by default in VISA applications. See
also primary VISA.
session
VISA term for a communication channel. An instance of a
communications path between a software element and a
resource. Every communication channel in VISA is unique.