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Chapter 9
Checking for Errors in LabWindows/CVI
LabWindows/CVI Programmer Reference Manual
9-4
©
 National Instruments Corporation
Easy I/O for DAQ Library
The Easy I/O for DAQ Library functions return a negative value when they detect an error. 
They return a positive value as a warning when they are able to complete their task but not in 
the way you might expect. This library uses a common set of error codes. The positive 
warning codes are the same absolute values as the negative error codes. Refer to the 
LabWindows/CVI Standard Libraries Reference Manual or the function panel help for a 
listing of the error codes and information on the individual functions. You can use 
GetDAQErrorString
 to get the error message associated with each Easy I/O for DAQ 
Library error or warning code.
Data Acquisition Library 
The Data Acquisition Library functions return a negative value when they detect an error. 
They return a positive value as a warning when they are able to complete their task but not in 
the way you might expect. This library uses a common set of error codes. The positive 
warning codes are the same absolute values as the negative error codes. 
Refer to the back of the NI-DAQ Function Reference Manual for PC Compatibles or the 
function panel help for a listing of the error codes. You can use 
GetNIDAQErrorString
 to 
get the error message associated with each Data Acquisition Library error or warning code.
VXI Library 
The VXI Library uses a variety of global variables and function return codes to report any 
error that occurs. You must check each function description to determine what error checking 
might be necessary. Refer to the specific VXI function reference manual or the on-line help 
for a listing of the error codes.
GPIB/GPIB 488.2 Library 
The GPIB libraries return status information through two global variables called 
ibsta
 
and
iberr
Note
If your program uses multiple threads, use the 
ThreadIbsta
 and 
ThreadIberr
 
functions in place of the 
ibsta
 and 
iberr
 global variables.
Note
The GPIB Library functions return the same value that they assign to 
ibsta
. You 
can choose to use either the return values, 
ibsta
, or 
ThreadIbsta
.
The 
ERR
 bit within 
ibsta
 indicates an error condition. If this bit is not set, 
iberr
 does not 
contain meaningful information. If the 
ERR
 bit is set in 
ibsta
, the error condition is stored in 
00ProRef.book : 06chap09.fm  Page 4  Monday, March 9, 1998  3:23 PM