Handle General Program Errors

ScanTools Plus Link allows you to suppress all ScanTools Plus general program error messages and customize the handling of general errors in your program.

Also see the sample programs installed with the SDK; they provide specific ways of handling program errors. Installed Samples Overview

To handle program errors, do the following:

1. Call ScanningManager.SetKernelErrorMode with L_CLIENTHANDLES_GENERRORS. This call instructs ScanningManager to fire the ServerMessageBox event when it encounters a general program error and the ScanError event when it encounters a scanner error.
2. Set up an event handler for the ServerMessageBox event. Like all the other events, this event has a single parameter of type ScanEventArgs. Within the ServerMessageBox event handler, the ScanEventArgs.ServerMessage object is available.
3. Within the event handler you can examine various properties of ScanEventArgs.ServerMessage - including ErrorNo, ErrorType, MessageText and Continue - to understand the error that just occurred.

• If ErrorType is L_ERRMSG_TYPE_FATAL the scanning session terminates after you exit from the event handler. All you can do is notify the user of this error condition via a message box.
• If ErrorType is L_ERRMSG_TYPE_NOT_FATAL you can treat it as an informational message that will not affect the scanning session. You could notify the user of this error condition via a message box or simply suppress it if you feel the message is irrelevant to the task at hand.
• If ErrorType is L_ERRMSG_TYPE_YESNO_YESFATAL the error condition is probably serious. You still have control over whether the session terminates or not. The default action is to terminate the session. You could solicit a response from the user or make a unilateral decision as the programmer.
• If ErrorType is L_ERRMSG_TYPE_YESNO_NOFATAL the error condition is probably serious. You still have control over whether the session terminates or not. The default action is to continue scanning. You could solicit a response from the user or make a unilateral decision as the programmer.
• If ErrorType is L_ERRMSG_TYPE_UNKNOWN an unknown error has occurred. Sall ScanningManager.Stop to terminate the scanning session.

4. After examining the errors, you can choose to have ScanTools Plus show the errors by setting ServerMessage.Display to true and simply return from the event handler. To suppress the display, set ServerMessage.Display to false and proceed to Step 5.
5. Set ServerMessage.Continue to tell ScanningManager whether or not to continue scanning. However, each error type listed above already has the appropriate action that occurs. If you are satisfied with the default action for the error condition you can skip this step. The types YESNO_YESFATAL and YESNO_NOFATAL are the only types where any action can be taken.

If the ErrorType is L_ERRMSG_TYPE_FATAL or L_ERRMSG_TYPE_NOT_FATAL, you cannot alter the course of action and this call will essentially do nothing. If the ErrorType is L_ERRMSG_TYPE_UNKNOWN, you must call ScanningManager.Stop to stop scanning right away.