User`s guide

148 Agilent VISA User’s Guide
Controller in Charge
The device currently in control of the GPIB.
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.