Chapter 6
NI-FBUS Function Reference
©
National Instruments Corporation
6-31
NI-FBUS Hardware and Software User Manual
For block, VFD, physical device, or link descriptors, the object name may refer to a variable
or a variable list. You normally would use
nifGetObjectAttributes
to read the type
description of a certain data type.
Refer to Table 6-5 for an explanation of how to use macros to specify the object.
For more detailed information concerning the
nifAttributes_t
structure, refer to
Chapter 3,
Using ddi_get_item
, of the
Fieldbus Foundation Device Description Services
User Guide
.
Note
After a successful call to
nifGetObjectAttributes
, your application must call
nifFreeObjectAttributes
when it is done using the
attr
structure. Your application
will not free up memory correctly if it does not perform this operation.
Return Values
E_OK
The call was successful.
E_CONFIG_ERROR
Some configuration information, such as registry information or
network configuration information, is incorrect.
E_INVALID_DESCRIPTOR
The device descriptor does not correspond to a VFD or block.
E_SYMBOL_FILE_NOT_FOUND
The NI-FBUS Communications Manager could not find the
symbol file.
E_SM_NOT_OPERATIONAL
The device is present, but cannot respond because it is at a default
address.
E_NOT_FOUND
The referred object does not exist, or it does not have object
attributes.
E_MULTIPLE
The NI-FBUS Communications Manager found more than
one identical tag; the function failed.
E_ORDINAL_NUM_OUT_OF_RANGE
The ordinal number is out of the device range.
E_OBSOLETE_DESC
The input descriptor is no longer valid. It was closed before
nifGetObjectAttributes
completed.
E_SERVER_CONNECTION_LOST
The session established with the NI-FBUS Communications
Manager for this descriptor has been closed or lost.