TestStand generates a run-time error when it encounters a condition that prevents a sequence from executing. For example, when a precondition refers to the status of a step that does not exist, TestStand generates a run-time error when it attempts to evaluate the precondition. TestStand also generates a run-time error when a code module causes an access violation or any other exception.

TestStand does not use run-time errors to indicate UUT test failures. Instead, a run-time error indicates a problem exists with the testing process itself and testing cannot continue. Usually, a code module reports a run-time error when it detects an error in a hardware or software resource it uses to perform a test.

When a run-time error occurs, the sequence runs steps in the Cleanup step group, if not already executing, and returns to the calling sequence. When a subsequence with a run-time error returns to a calling sequence, TestStand sets the calling sequence step status to Error, and the calling sequence continues to propagate the run-time error up the call stack unless you enabled the Ignore Run-Time Errors option on the Run Options panel of the Step Settings pane for the Sequence Call step. When you enable this setting, TestStand ignores the error for the thread, and the thread execution continues normally. If TestStand returns the run-time error to the root sequence invocation, the result status for the execution is Error.

To interactively handle run-time errors, configure TestStand to launch the Run-Time Error dialog box in the event of an error by selecting Show Dialog from the On Run-Time Error ring control on the Execution tab of the Station Options dialog box.

You can also invoke Post-Step RunTime Error Engine callbacks when a run-time error occurs.