VXI Mainframe Backplane (BACKPLANE) Resource

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VXI Mainframe Backplane (BACKPLANE) Resource

This topic describes the VXI Mainframe Backplane (BACKPLANE) Resource that encapsulates the VXI-defined operations and properties of the backplane in a VXIbus system.

BACKPLANE Resource Overview

A VISA VXI Mainframe Backplane Resource, like any other resource, starts with the basic operations and attributes of the VISA Resource Template. For example, modifying the state of an attribute is done via the operation viSetAttribute, which is defined in the VISA Resource Template.

Although the BACKPLANE resource does not have viSetAttribute listed in its operations, it provides the operation because it is defined in the VISA Resource Template. From this basic set, each resource adds its specific operations and attributes that allow it to perform its dedicated task.

The BACKPLANE Resource lets a controller query and manipulate specific lines on a specific mainframe in a given VXI system. Services are provided to map, unmap, assert, and receive hardware triggers, and also to assert various utility and interrupt signals. This includes advanced functionality that may not be available in all implementations or all vendors' controllers.

A VXI system with an embedded CPU with one mainframe will always have exactly one BACKPLANE resource. Valid examples of resource strings for this are VXI0::0::BACKPLANE and VXI::BACKPLANE. A multi-chassis VXI system may provide only one BACKPLANE resource total, but the recommended way is to provide one BACKPLANE resource per chassis, with the resource string address corresponding to the attribute VI_ATTR_MAINFRAME_LA. If a multi-chassis VXI system provides only one BACKPLANE resource, it is assumed to control the backplane resources in all chasses.

Note: Some VXI or GPIB-VXI implementations view all mainframes in a VXI system as one entity. In these configurations, separate BACKPLANE resources are not possible.

BACKPLANE Resource Attributes

Note: AP = Access Privileges

Attribute Name	AP		Type	Range	Default
Generic BACKPLANE Resource Attributes
VI_ATTR_INTF_INST_NAME	RO	Global	ViString	N/A	N/A
VI_ATTR_INTF_NUM	RO	Global	ViUInt16	0 to FFFFh	0
VI_ATTR_INTF_TYPE	RO	Global	ViUInt16	VI_INTF_VXI VI_INTF_GPIB_VXI	N/A
VI_ATTR_TMO_VALUE	RW	Local	ViUInt32	VI_TMO_IMMEDIATE 1 to FFFFFFFEh VI_TMO_INFINITE	2000 msec.
VXI and GPIB-VXI Specific BACKPLANE Resource Attributes
VI_ATTR_MAINFRAME_LA	RO	Global	ViInt16	0 to 255 VI_UNKNOWN_LA	N/A
VI_ATTR_TRIG_ID	RW	Local	ViInt16	VI_TRIG_TTL0 to VI_TRIG_TTL7; VI_TRIG_ECL0 to VI_TRIG_ECL1	N/A
VI_ATTR_VXI_TRIG_STATUS	RO	Global	ViUInt32	N/A	N/A
VI_ATTR_VXI_TRIG_SUPPORT	RO	Global	ViUInt32	N/A	N/A
VI_ATTR_VXI_VME_INTR_STATUS	RO	Global	ViUInt16	N/A	N/A
VI_ATTR_VXI_VME_SYSFAIL_STATE	RO	Global	ViInt16	VI_STATE_ASSERTED VI_STATE_UNASSERTED VI_STATE_UNKNOWN	N/A

BACKPLANE Resource Attribute Descriptions

Attribute Name	Description
Generic BACKPLANE Resource Attributes
VI_ATTR_INTF_INST_NAME	Human-readable text describing the given interface.
VI_ATTR_INTF_NUM	Board number for the given interface.
VI_ATTR_INTF_TYPE	Interface type of the given session.
VI_ATTR_TMO_VALUE	Minimum timeout value to use, in milliseconds. A timeout value of VI_TMO_IMMEDIATE means that operations should never wait for the device to respond. A timeout value of VI_TMO_INFINITE disables the timeout mechanism.
VXI and GPIB-VXI Specific BACKPLANE Resource Attributes
VI_ATTR_MAINFRAME_LA	This is the logical address of a given device in the mainframe, usually the device with the lowest logical address. Other possible values include the logical address of the Slot 0 controller or of the parent-side extender. Often, these are all the same value. The purpose of this attribute is to provide a unique ID for each mainframe. A VISA manufacturer can choose any of these values, but must be consistent across mainframes. If this value is not known, the attribute value returned is VI_UNKNOWN_LA.
VI_ATTR_TRIG_ID	Identifier for the current triggering mechanism.
VI_ATTR_VXI_TRIG_STATUS	This attribute shows the current state of the VXI trigger lines. This is a bit vector with bits 0-9 corresponding to VI_TRIG_TTL0 through VI_TRIG_ECL1.
VI_ATTR_VXI_TRIG_SUPPORT	This attribute shows which VXI trigger lines this implementation supports. This is a bit vector with bits 0-9 corresponding to VI_TRIG_TTL0 through VI_TRIG_ECL1. Agilent VISA also returns 12 to indicate VI_TRIG_PANEL_IN for received triggers and VI_TRIG_PANEL_OUT for asserted triggers on Agilent VXI controllers.
VI_ATTR_VXI_VME_INTR_STATUS	This attribute shows the current state of the VXI/VME interrupt lines. This is a bit vector with bits 0-6 corresponding to interrupt lines 1-7.
VI_ATTR_VXI_VME_SYSFAIL_STATE	This attribute shows the current state of the VXI/VME SYSFAIL (SYStem FAILure) backplane line.

BACKPLANE Resource Events

This resource defines the following events for communication with applications, where AP = Access Privilege.

VI_EVENT_TRIG - Notification that a trigger interrupt was received from the backplane. For VISA, the only triggers that can be sensed are VXI hardware triggers on the assertion edge (SYNC and ON trigger protocols only).
Event Attribute	Description	AP	Type	Range
VI_ATTR_EVENT_TYPE	Unique logical identifier of the event.	RO	ViEventType	VI_EVENT_TRIG
VI_ATTR_RECV_TRIG_ID	The identifier of the triggering mechanism on which the specified trigger event was received.	RO	ViInt16	VI_TRIG_TTL0 to VI_TRIG_TTL7; VI_TRIG_ECL0 to VI_TRIG_ECL1

VI_EVENT_VXI_VME_SYSFAIL - Notification that the VXI/VME SYSFAIL* line has been asserted.
Event Attribute	Description	AP	Data Type	Range
VI_ATTR_EVENT_TYPE	Unique logical identifier of the event.	RO	ViEventType	VI_EVENT_VXI_VME_SYSFAIL

VI_EVENT_VXI_VME_SYSRESET - Notification that the VXI/VME SYSRESET* line has been reset.
Event Attribute	Description	AP	Type	Range
VI_ATTR_EVENT_TYPE	Unique logical identifier of the event.	RO	ViEventType	VI_EVENT_VXI_VME_SYSRESET

BACKPLANE Resource Operations

viAssertTrigger (vi, protocol)

viAssertUtilSignal(vi, line)

viAssertIntrSignal(vi, mode, statusID)
viMapTrigger (vi, trigSrc, trigDest, mode)
viUnmapTrigger (vi, trigSrc, trigDest)

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