User`s guide

Programming with VISA 3
Agilent VISA User’s Guide 31
VISA Attributes
Attributes are associated with resources or sessions. You
can use attributes to determine the state of a resource or
session, or to set a resource or session to a specified state.
For example, you can use the viGetAttribute function to
read the state of an attribute for a specified session, event
context, or find list. There are read only (RO) and
read/write (RW) attributes. Use the viSetAttribute function
to modify the state of a read/write attribute for a specified
session, event context, or find list.
The pointer passed to viGetAttribute must point to the
exact type required for that attribute (ViUInt16, ViInt32,
etc.). For example, when reading an attribute state that
returns a ViUInt16, you must declare a variable of that type
and use it for the returned data. If ViString is returned, you
must allocate an array and pass a pointer to that array for
the returned data.
Table 4 Descriptions of Resource Classes Supported by Agilent VISA
Resource Class Interface Types Resource Class Description
Instrument Control
(INSTR)
Generic, GPIB,
GPIB-VXI, Serial,
TCPIP, USB, VXI
Device operations (reading,
writing, triggering, etc.).
GPIB Bus Interface
(INTFC)
Generic, GPIB Raw GPIB interface operations
(reading, writing, triggering,
etc.).
Memory Access
(MEMACC)
Generic, GPIB-VXI,
VXI
Address space of a
memory-mapped bus such as
the VXIbus.
VXI Mainframe
Backplane
(BACKPLANE)
Generic, GPIB-VXI,
VXI (GPIB-VXI
BACKPLANE not
supported)
VXI-defined operations and
properties of each backplane (or
chassis) in a VXIbus system.
TCPIP Socket
(SOCKET)
Generic, TCPIP Operations and properties of a
raw network socket connection
using TCPIP.