Once the relationships between failure effects and output functions has been established within a lower-level model and inherited into the upper-level assembly, the inherited failure effects can be used to control lower-level coverage within an upper-level test that includes one or more functions of that assembly in its coverage.
When editing the test, select the assembly in question. On the Test Coverage panel for that assembly, disable any functions that are not associated the test coverage. Then click on the “Failure Effects” option to display coverage in terms of failure effects.
Listed on the panel will be all object effects that are associated with functions that were previously enabled on this panel. Effects associated with functions that have already been removed from the coverage—due to state settings, coverage anchors, disabled stimuli, explicit non-detection, or simply because they are not in the coverage path—will not be included in this list.
The final step is to disable any object failure effects on the assembly for which you wish to exclude lower-level failure modes from the test coverage. For any disabled effect, lowest-level failure mode causes will be excluded from the test coverage (provided that they are not also causes of any of the effects that remain enabled for that assembly).
The coverage is resolved when diagnostics are generated, so there is unfortunately no way to see this during test editing. If you examine the isolated fault groups calculated by the diagnostics, however, you will see that the impact of these settings.
In this excerpt from the Fault Group Details Report, only lower-level failure modes that propagate to the selected failure effects on the top-level test have been included in the isolated fault group. In this example, because the failure effect “Reduced noise immunity from decoupling failure” was deselected in the coverage for this test, the “Failed Open” failure modes for the decoupling capacitors were not included in the test’s coverage—and therefore not isolated in the fault group.
