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Unreachable execution path

Diagnostic action to take when an unreachable execution path is detected

Model Configuration Pane: Diagnostics


The Unreachable execution path parameter specifies the diagnostic action to take when there are chart constructs not on a valid execution path. These constructs can cause unreachable execution paths:

  • Dangling transitions not connected to a destination state, junction, or port

    Chart that contains a dangling transition.

  • Transition shadowing caused by an unconditional transition that prevents other transitions from the same source from executing

    Chart with an unconditional transition that shadows a conditional transition.

  • States, junctions, or ports not connected with a transition from a reachable source

    Chart that contains an unreachable state.

  • Unconditional transitions leading out of a state that prevent the execution of the during actions in the state and the transitions between child states

    Chart with one transition out of a state with during actions and another transition out of a state with child states.

This diagnostic does not detect unreachable execution paths caused by transition conditions that are always true or false. For example, in this chart, the diagnostic does not detect that the unconditional transition to state D is never valid.

Chart that contains an unconditional transition that is never valid.

If you have Simulink® Design Verifier™, you can use dead logic detection to analyze your chart for this type of unreachable execution path. For more information, see Dead Logic Detection (Simulink Design Verifier).


warning (default) | none | error

No warning or error appears.


A warning appears.


An error appears and stops the simulation.

Recommended Settings

TraceabilityNo impact
EfficiencyNo impact (for simulation)
none (for production code generation)
Safety precautionerror

Programmatic Use

Parameter: SFUnreachableExecutionPathDiag
Value: 'none' | 'warning' | 'error'
Default: 'warning'

Version History

Introduced in R2016b