National Instruments BridgeVIEW A

This appendix describes error handling for BridgeVIEW VIs and contains

an explanation of the VIs in the BridgeVIEW VI library. In this appendix,

the VIs are arranged alphabetically, first by VI Library name (Alarms

and Events, Historical Data, System, Tags, and Tag Attributes), then by

VI name.

Errors that occur in the VIs in the BridgeVIEW VI Library can be handled in one of two ways:

by the BridgeVIEW Engine or by each VI. The BridgeVIEW Engine handles errors for the

Tags VIs and the Alarms and Events VIs. The other VIs include standard error in and error

out parameters for error handling.

These two methods of error handling are described in detail below. For information about

how you can handle errors in your own VIs, see the section Check for Errors in Chapter 16,

Program Design.

BridgeVIEW reports error handling information for Tags VIs, Tag Attributes VIs, and

Alarms and Events VIs to the system. If you try to access a tag that does not exist in the Tags

VIs or the Alarms and Events VIs, the BridgeVIEW Engine reports an error. The error shows

up in the BridgeVIEW Engine Manager display. For more information about the Engine

Manager, see Chapter 2, BridgeVIEW Environment.

If a BridgeVIEW VI does not report to the BridgeVIEW Engine, it uses a standard control

and indicator (error in and error out) to notify you that an error has occurred. The error in

and error out parameters are described here.

error in (no error) is a cluster that describes the error status before this VI

executes. If error in indicates that an error occurred before this VI was

called, this VI might choose not to execute its function, but just pass the

error through to its error out cluster. If no error has occurred, this VI

executes normally and sets its own error status in error out. Use the error

handler VIs to look up the error code and to display the corresponding error