
Chapter 6
NI-FBUS Function Reference
©
National Instruments Corporation
6-53
NI-FBUS Hardware and Software User Manual
Description
nifWriteObject
writes the values of a function block parameter to a device.
•
If
ud
is the descriptor of a session or link, then
name
must be in the format
BLOCKTAG.PARAM_NAME
.
•
If
ud
is a session descriptor, then all links are searched for the given
BLOCKTAG.PARAM_NAME
. The function fails if more than one identical
BLOCKTAG.PARAM_NAME
match is found.
•
If
ud
is a physical device descriptor, a parameter is written by
BLOCKTAG.PARAM_NAME
.
•
If
ud
is the descriptor of a general Virtual Field Device, then name must be in the format
BLOCKTAG.PARAM_NAME
.
•
If
ud
is the descriptor of a function block,
name
must be in the format
PARAM_NAME
.
•
If
ud
is the descriptor of a function block, and you use the
NIFB_INDEX
or
NIFB_INDEX_SUBINDEX
macro, the index specified is the relative index of the
parameter within the block. Relative indices start at one for the first parameter.
•
In all descriptor cases, you can expand
PARAM_NAME
itself to
STRUCT.ELEMENT
format
to represent a named element of a named structure.
Refer to Table 6-5 for an explanation of how to use macros to specify the parameter.
Return Values
E_OK
The call was successful.
E_INVALID_DESCRIPTOR
The device descriptor does not correspond to a VFD.
E_SYMBOL_FILE_NOT_FOUND
The NI-FBUS Communications Manager could not find the
symbol file.
E_ORDINAL_NUM_OUT_OF_RANGE
The parameter is out of the device range.
E_OBJECT_ACCESS_UNSUPPORTED
The device does not support write access to this object.
E_MULTIPLE
The NI-FBUS Communications Manager found more than
one identical tag. The function failed.
E_SM_NOT_OPERATIONAL
The device is present, but cannot respond because it is at a default
address.
E_COMM_ERROR
The NI-FBUS Communications Manager failed to communicate
with the device.
E_PARAMETER_CHECK
The device reported a violation of parameter-specific checks.
E_EXCEED_LIMIT
The device reported that the value exceeds the limit.