User`s guide

134 Agilent VISA User’s Guide
Glossary
device
A unit that receives commands from a Controller. A device is
typically an instrument, but can also be a computer acting in a
non-Controller role or another peripheral such as a printer or plotter.
In VISA, a device is logically represented by the association of
several VISA resources.
device descriptor
A handle, returned from ibdev or ibfind, that uniquely identifies a
device in Agilent 488 original API calls. Also called a device unit
descriptor.
device driver
Software code that communicates with a device: for example, a
printer driver that communicates with a printer from a PC. A device
driver may either communicate directly with a device by reading to
and writing from registers, or it may communicate through an
interface driver.
device session
A session that communicates as a Controller with a single, specific
device such as an instrument.
device-level
Refers to Agilent 488 functions that operate on a device (instrument),
rather than on an interface.
direct I/O
Programmatic communication with instruments not involving an
instrument driver. Direct I/O may be accomplished by using an IO
Library (VISA, VISA COM, SICL, or Agilent 488) or by using
direct I/O tools such as those provided by Agilent VEE.
driver
See instrument driver and device driver.