Documentation Center

  • Trial Software
  • Product Updates

Process Events Using Inner Transitions

Process Events with an Inner Transition in an Exclusive (OR) State

This example shows what happens when processing three events using an inner transition in an exclusive (OR) state.

Process One Event in an Exclusive (OR) State

This example shows the behavior of an inner transition. The chart uses implicit ordering of outgoing transitions (see Implicit Ordering of Outgoing Transitions).

Initially, the chart is asleep. State A is active. Condition [C_one] is false. Event E_one occurs and awakens the chart, which processes the event from the root down through the hierarchy:

  1. The chart root checks to see if there is a valid transition as a result of E_one. A potentially valid transition from state A to state B is detected. However, the transition is not valid, because [C_one] is false.

  2. State A during actions (durA()) execute and complete.

  3. State A checks its children for a valid transition and detects a valid inner transition.

  4. State A remains active. The inner transition action A_two is executed and completed. Because it is an inner transition, state A's exit and entry actions are not executed.

  5. The chart goes back to sleep.

This sequence completes the execution of this Stateflow® chart associated with event E_one.

Process a Second Event in an Exclusive (OR) State

Using the previous example, this example shows what happens when a second event E_one occurs. The chart uses implicit ordering of outgoing transitions (see Implicit Ordering of Outgoing Transitions).

Initially, the chart is asleep. State A is still active. Condition [C_one] is true. Event E_one occurs and awakens the chart, which processes the event from the root down through the hierarchy:

  1. The chart root checks to see if there is a valid transition as a result of E_one.

    The transition from state A to state B is now valid because [C_one] is true.

  2. State A exit actions (exitA()) execute and complete.

  3. State A is marked inactive.

  4. The transition action A_one is executed and completed.

  5. State B is marked active.

  6. State B entry actions (entB()) execute and complete.

  7. The chart goes back to sleep.

This sequence completes the execution of this Stateflow chart associated with event E_one.

Process a Third Event in an Exclusive (OR) State

Using the previous example, this example shows what happens when a third event, E_two, occurs. The chart uses implicit ordering of outgoing transitions (see Implicit Ordering of Outgoing Transitions).

Initially, the chart is asleep. State B is now active. Condition [C_two] is false. Event E_two occurs and awakens the chart, which processes the event from the root down through the hierarchy:

  1. The chart root checks to see if there is a valid transition as a result of E_two.

    A potentially valid transition from state B to state A is detected. The transition is not valid because [C_two] is false. However, active state B has a valid self-loop transition.

  2. State B exit actions (exitB()) execute and complete.

  3. State B is marked inactive.

  4. The self-loop transition action, A_four, executes and completes.

  5. State B is marked active.

  6. State B entry actions (entB()) execute and complete.

  7. The chart goes back to sleep.

This sequence completes the execution of this Stateflow chart associated with event E_two. This example shows the difference in behavior between inner and self-loop transitions.

Process Events with an Inner Transition to a Connective Junction

This example shows the behavior of handling repeated events using an inner transition to a connective junction.

Process the First Event with an Inner Transition to a Connective Junction

This example shows the behavior of an inner transition to a connective junction for the first event. The chart uses implicit ordering of outgoing transitions (see Implicit Ordering of Outgoing Transitions).

Initially, the chart is asleep. State A1 is active. Condition [C_two] is true. Event E_one occurs and awakens the chart, which processes the event from the root down through the hierarchy:

  1. The chart root checks to see if there is a valid transition at the root level as a result of E_one. There is no valid transition.

  2. State A during actions (durA()) execute and complete.

  3. State A checks itself for valid transitions and detects that there is a valid inner transition to a connective junction.

    The conditions are evaluated to determine whether one of the transitions is valid. Because implicit ordering applies, the segments labeled with a condition are evaluated before the unlabeled segment. The evaluation starts from a 12 o'clock position on the junction and progresses in a clockwise manner. Because [C_two] is true, the inner transition to the junction and then to state A.A2 is valid.

  4. State A.A1 exit actions (exitA1()) execute and complete.

  5. State A.A1 is marked inactive.

  6. State A.A2 is marked active.

  7. State A.A2 entry actions (entA2()) execute and complete.

  8. The chart goes back to sleep.

This sequence completes the execution of this Stateflow chart associated with event E_one when state A1 is active and condition [C_two] is true.

Process a Second Event with an Inner Transition to a Connective Junction

Continuing the previous example, this example shows the behavior of an inner transition to a junction when a second event E_one occurs. The chart uses implicit ordering of outgoing transitions (see Implicit Ordering of Outgoing Transitions).

Initially, the chart is asleep. State A2 is active. Condition [C_two] is true. Event E_one occurs and awakens the chart, which processes the event from the root down through the hierarchy:

  1. The chart root checks to see if there is a valid transition at the root level as a result of E_one. There is no valid transition.

  2. State A during actions (durA()) execute and complete.

  3. State A checks itself for valid transitions and detects a valid inner transition to a connective junction.

    The conditions are evaluated to determine whether one of the transitions is valid. Because implicit ordering applies, the segments labeled with a condition are evaluated before the unlabeled segment. The evaluation starts from a 12 o'clock position on the junction and progresses in a clockwise manner. Because [C_two] is true, the inner transition to the junction and then to state A.A2 is valid.

  4. State A.A2 exit actions (exitA2()) execute and complete.

  5. State A.A2 is marked inactive.

  6. State A.A2 is marked active.

  7. State A.A2 entry actions (entA2()) execute and complete.

  8. The chart goes back to sleep.

This sequence completes the execution of this Stateflow chart associated with event E_one when state A2 is active and condition [C_two] is true. For a state with a valid inner transition, an active substate can be exited and reentered immediately.

Inner Transition to a History Junction

This example shows the behavior of an inner transition to a history junction.

Initially, the chart is asleep. State A.A1 is active. History information exists because superstate A is active. Event E_one occurs and awakens the chart, which processes the event from the root down through the hierarchy:

  1. The chart root checks to see if there is a valid transition as a result of E_one. There is no valid transition.

  2. State A during actions execute and complete.

  3. State A checks itself for valid transitions and detects that there is a valid inner transition to a history junction. Based on the history information, the last active state, A.A1, is the destination state.

  4. State A.A1 exit actions execute and complete.

  5. State A.A1 is marked inactive.

  6. State A.A1 is marked active.

  7. State A.A1 entry actions execute and complete.

  8. The chart goes back to sleep.

This sequence completes the execution of this Stateflow chart associated with event E_one when there is an inner transition to a history junction and state A.A1 is active. For a state with a valid inner transition, an active substate can be exited and reentered immediately.

Was this topic helpful?