Documentation

Issue: States and junctions must not overlap in the Stateflow Editor.

Diagnostic level: Error.

Solution: Avoid intersections by separating the states and junctions.

Issue: Charts and states with parallel (AND) decomposition do not support monitoring of leaf or child state activity because parallel substates are active simultaneously.

Diagnostic level: Warning.

Solution: Open the Property Inspector or the Model Explorer. Clear the Create output for monitoring check box or select Self activity from the drop-down list. For more information, see Monitor State Activity Through Active State Data.

Issue: A state action does not follow the Stateflow syntax rules. The Stateflow Editor underlines syntax errors with a red, wavy line.

Diagnostic level: Error.

Solution: Correct the syntax error in the state action. For more information, see State Labels.

Issue: A state is unreachable when no valid execution path leads to it.

Diagnostic level: Depends on the configuration parameter Unreachable execution path.

Solution: Connect the unreachable state with a transition from a reachable state or junction.

Issue: Every transition must have a valid destination state or junction.

Diagnostic level: Depends on the configuration parameter Unreachable execution path.

Solution: Connect the transition to a state or junction. For more information, see Transitions.

Issue: In a chart or state with exclusive (OR) decomposition and at least two substates or junctions, a default transition is required to indicate where the execution begins.

Diagnostic level: Error.

Solution: Specify an initial state by adding a default transition. For more information, see Default Transitions.

Issue: In charts or states with exclusive (OR) decomposition and at least one substate:

Diagnostic level: Depends on the configuration parameter No unconditional default transitions.

Solution: Terminate every path along the default transition in a substate. Ensure that one default transition path is not guarded by a condition or triggered by an event.

Issue: A default transition path must not exit the parent state.

Diagnostic level: Error.

Solution: Modify the default transition path so it stays within the parent state.

Issue: Transitions must not enter a graphical function. Stateflow charts call graphical functions from state actions or transitions.

Diagnostic level: Error.

Solution: Delete the transition entering the graphical function.

Issue: In a transition, a condition or action does not follow the Stateflow syntax rules. The Stateflow Editor underlines syntax errors with a red, wavy line.

Diagnostic level: Error.

Solution: Correct the syntax error in the transition condition or action. For more information, see Transition Labels.

Issue: When a transition with a transition action is followed by a transition with a condition action, the actions are not executed in the order of the transitions. Stateflow charts execute condition actions when the associated condition is evaluated as true. In contrast, charts execute transition actions only when the transition path is fully executed. As a consequence, a chart takes a transition path, the condition actions occur before the transition actions.

Diagnostic level: Depends on the configuration parameter Transition action specified before condition action.

Solution: Place the transition action after the last condition action on the path.

Issue: In charts and states with parallel (AND) decomposition, all sibling states are active or inactive at the same time.

Diagnostic level: Warning.

Solution: Remove the transitions or change the decomposition of the parent state to exclusive (OR).

Issue: Transitions can only connect to states and junctions.

Diagnostic level: Error.

Solution: Move or delete the transitions attached to the box.

Issue: Standalone Stateflow charts do not support transitions that cross the boundary of a parallel state.

Diagnostic level: Error.

Solution: Delete the transition crossing into or out of the parallel states.

Issue: Transitions must not exit a graphical function. Flow charts in graphical functions must be completely contained inside the function.

Diagnostic level: Error.

Solution: Delete the transition exiting the graphical function.

Issue: If a transition goes outside the parent state between the source and destination, the chart executes the exit and entry actions of the parent state before the destination state becomes active.

Diagnostic level: Depends on the configuration parameter Transition outside natural parent.

Solution: Move the transition so that it is contained within the parent state.

Issue: When an unconditional transition executes before other outgoing transitions from the same source, it prevents the other transitions from executing.

Diagnostic level: Depends on the configuration parameter Unreachable execution path.

Solution: Create no more than one unconditional transition from each state or junction. Explicitly specify that the unconditional transition executes after any transitions with conditions. For more information, see Transition Evaluation Order.

Issue: Unconditional transitions leading out of a state inhibit the execution of the during actions in the state and the default transitions to child states.

Diagnostic level: Depends on the configuration parameter Transition outside natural parent.

Solution: Add a condition to the transition or remove during actions and child states from the state.

Issue: Cycles should not contain transitions with transition actions.

Diagnostic level: Error.

Solution: Remove the transition action or remove the cycle by deleting a transition.

Issue: A history junction is invalid when:

Diagnostic level: Error.

Solution: Remove the history junction from the chart level of the hierarchy, a state with parallel (AND) decomposition, or a graphical function. Remove all but one history junction from the state. Move the transition source to a connective junction or a state. For more information, see Record State Activity by Using History Junctions.

Issue: A junction must have an unconditional escape path from a cycle to a state or terminating junction.

Diagnostic level: Error.

Solution: Create an unconditional path from the junction to a state or terminating junction.

Issue: Unintended backtracking of control flow can occur when:

Diagnostic level: Depends on the configuration parameter Unexpected backtracking.

Solution: Create an unconditional path from the junction to a state or terminating junction. For more information, see Backtrack in Flow Charts.

For example, the highlighted junction in this chart does not have an unconditional transition path to state A. If ConditionA and ConditionB are true and ConditionC is false, the chart backtracks to the first junction in the path multiple times. As a result, the chart executes the three condition actions.

To avoid backtracking, combine the conditions and create an unconditional path from the second junction to the destination state. After the change, the chart executes only one condition action.

Issue: A junction is unreachable when no valid execution path leads to it.

Diagnostic level: Depends on the configuration parameter Unreachable execution path.

Solution: Connect the unreachable junction with a transition from a reachable state or junction.

Issue: A function is unused when a chart when there are no statements that call the function.

Diagnostic level: Warning.

Solution: Call the function from a state or transition action or from another function.

Issue: Because graphical functions execute completely in a single time step, they must not contain any states.

Diagnostic level: Error.

Solution: Replace the states with junctions. For more information, see Reuse Logic Patterns by Defining Graphical Functions.

Issue: A function definition uses a reserved keyword as an argument.

Diagnostic level: Error.

Solution: Rename the argument to the function. For a list of reserved keywords, see Rules for Naming Stateflow Objects.