VISA Attributes

This topic summarizes the attributes of the VISA Template, VISA resource classes, and shows applicable interface types for each resource class supported by Agilent VISA.

Note: Although the Servant Device-Side (SERVANT) Resource is defined by the VXIplug&play Systems Alliance VISA Library specification, the SERVANT Resource is not supported in Agilent VISA and is not described in this help. The SERVANT Resource is intended for advanced users who need to write firmware that exports device functionality across multiple resources.

VISA Template Attributes

See the topic below for a list of attributes for the VISA Template.

VISA Template Attributes

Resource Class Descriptions

See these topics for five resource classes supported by Agilent VISA. (the SERVANT resource cClass is not supported by Agilent VISA). The description for each resource class includes a resource overview, resource attributes, resource events, and resource operations (functions).

Instrument Control (INSTR) Resource

Memory Access (MEMACC) Resource

GPIB Bus Interface (INTFC) Resource

VXI Mainframe Backplane (BACKPLANE) Resource

TCPIP Socket (SOCKET) Resource

Note: Attributes are local or global. A local attribute only affects the session specified. A global attribute affects the specified device from any session. Attributes can also be read only (RO) and read/write (RW). The Generic Attributes listed apply to all listed interface types. For example, VI_ATTR_INTF_NUM is listed as a Generic INSTR Resource Attribute, so VI_ATTR_INTF_NUM applies to the GPIB, GPIB-VXI, VXI, ASRL, and TCPIP interfaces as well.

Resource Classes vs. Interface Types

The following table shows the six resource classes that a complete VISA system, fully compliant with the VXIplug&play Systems Alliance specification, can implement. Since not all VISA implementations may implement all resource classes for all interfaces, the following table also shows the interfaces applicable to various resource classes.

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.
Servant Device-Side Resource (SERVANT)	Not Supported (GPIB, VXI, TCPIP)	Operations and properties of the capabilities of a device and a device's view of the system in which it exists.
TCPIP Socket (SOCKET)	Generic, TCPIP	Operations and properties of a raw network socket connection using TCPIP.

Interface Types vs. Resource Classes

This table shows the five interface types supported by Agilent VISA and the associated resource classes for each interface type.

Interface Type	Supported Resource Classes
ASRL	Instrument Control (INSTR)
GPIB	Instrument Control (INSTR) GPIB Bus Interface (INTFC)
GPIB-VXI	Instrument Control (INSTR) Memory Access (MEMACC)
TCPIP	Instrument Control (INSTR) TCPIP Socket (SOCKET)
USB	Instrument Control (INSTR)
VXI	Instrument Control (INSTR) Memory Access (MEMACC) VXI Mainframe Backplane (BACKPLANE)

See Also:

VISA Attribute Values