National Instruments FOUNDATION NI-FBUS Hardware And Software User Manual page 76

Chapter 6 NI-FBUS Function Reference
nifOpenBlock
Purpose
Returns a descriptor representing a block.
Format
nifError_t
nifError_t
Input
ud
blockTag
Output
out_ud
Context
VFD, physical device, link, session.
Description
nifOpenBlock
link, physical device, or VFD descriptor to this function.
There are two ways to specify the block: by tag and by ordinal number. To open the
block by its tag, you must set
Communications Manager returns an error if it finds more than one block with the
same tag. You can obtain the list of block tags within a specified VFD with a call to
nifGetBlockList
To open the block by its ordinal number, use the
only if is a VFD descriptor. The first block in a VFD has the ordinal number zero. Notice
ud
that the first block in a VFD is always the resource block.
NI-FBUS Hardware and Software User Manual
nifOpenBlock (
nifDesc_t ud,
char *blockTag,
nifDesc_t *out_ud)
nifOpenBlock (
nifDesc_t ud,
NIFB_ORDINAL(n),
nifDesc_t *out_ud)
A valid session, link, physical device, or VFD descriptor.
The tag of the block. To access a block by ordinal number within
a VFD, use the
file. You can only access a block by ordinal number for VFD
descriptors.
A descriptor for the block you request.
returns a descriptor for the block you specify. You must pass a valid session,
blockTag
.
macro in the
NIFB_ORDINAL
to the current tag of the block. The NI-FBUS
NIFB_ORDINAL
6-14
header
nifbus.h
macro. This macro is valid
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