Why does model coverage in Simulink Verification and Validation return uncovered conditions for temporal logic events in Stateflow charts?

I am using Simulink Verification and Validation 1.1.1 (R14SP3) to analyze model coverage for a Stateflow chart. The chart uses the following temporal logic event:

after(a,tick)

The model coverage report indicates that the TICK event is an uncovered condition, i.e., it never evaluates as 'false'. However, this is an implicit Stateflow event that should not appear as an uncovered condition. To reproduce this issue, simulate the attached model "test.mdl".

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated in Release 2011a (R2011a). For previous product releases, read below for any possible workarounds:

This is expected behavior in Simulink Verification and Validation. The temporal logic event syntax in Stateflow introduces unachievable coverage points, such as a TICK event that can never be 0 (i.e., false).

To work around this issue, replace the temporal logic event "after(a,tick)" with the following condition:

[after(a,tick)]

This temporal condition does not depend on an event and generates more efficient code.