National Instruments 320685D-01 TCP Library, DDE Library , ActiveX Automation Library, X Property Library, Formatting and I/O Library

Chapter 9 Checking for Errors in LabWindows/CVI

LabWindows/CVI Programmer Reference Manual 9-6

National Instruments Corporation

TCP Library

The TCP Library functions return a negative value when they detect an error. This library uses

a common set of error codes, which the LabWindows/CVI Standard Libraries Reference

Manual and the LabWindows/CVI function panel help list. You can use

GetTCPErrorString to get the error message associated with each TCP Library error code.

DDE Library

The DDE Library functions return a negative value when they detect an error. This library

uses a common set of error codes, which the LabWindows/CVI Standard Li br arie s Refe rence

Manual and the LabWindows/CVI function panel help list. You can use the function

GetDDEErrorString to get the error message associated with each DDE Library error code.

ActiveX Automation Library

The ActiveX Automation Library functions return a negative value when they detect an error.

This library uses a common set of 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 CA_GetAutomationErrorString to

get the error message associated with each ActiveX Automation Library error code.

X Property Library

The X Property Library functions return a negative value when they detect an error. This

library uses a common set of error codes, which the LabWindows/CVI Standard Libraries

Reference Manual and the LabWindows/CVI function panel help list. You can use the

function GetXPropErrorString to get the error message associated with each X Property

Library error code.

Formatting and I/O Library

This library contains the file I/O, string manipulation, and data formatting functions. All

functions return negative error codes when they detect an error. However, you must keep in

mind an important fact. When you enable debugging, the LabWindows/CVI environment

keeps track of the sizes of strings and arrays. If it detects any attempt to access a string or array

beyond its boundary, the environment halts the program and informs you. It is important to

remember that this feature works only when you execute source code in the

LabWindows/CVI development environment. The string functions can write bey ond the end

of a string or array without detection, resulting in corruption of memory . Therefore, y ou must

use the Formatting and I/O functions on strings and arrays with caution.

In addition to the return codes, the GetFmtErrNdx and NumFmtdBytes functions

returninformation on how the last scanning and formatting function executed. The

GetFmtIOError function returns a code that contains specific error information on the last