Event Triggering in Discrete-Event Charts

Event Triggering

SimEvents® discrete-event system charts support these events in the chart:

  • Message

  • Temporal

  • Local

  • Implicit (enter, exit, on, change)

SimEvents discrete-event system charts do not support these events in the chart:

  • Conditions without event

  • during, tick

  • Event input from Simulink®

  • Event output to Simulink


The SimEvents event calendar displays and prioritizes message, and temporal events. Events of these types execute according to the event calendar schedule.

The event calendar does not display or prioritize local and implicit events. In the SimEvents environment, these events execute as dependent events of message or temporal events. For parallel states, local and implicit events execute in the state execution order.

Message Triggering

When a message arrives at a message input or local queue, the discrete-event chart responds to the message as follows:

  • If the discrete-event chart is in a state of waiting for a message, the discrete-event chart wakes up and makes possible transitions. The chart immediately wakes up in order of message priority, processing the message with the highest priority first.

  • If the discrete-event chart does not need to respond to the arriving message, the discrete-event chart does not wake up and the message is queued.

Temporal Triggering

In a discrete-event chart, you can use both event-based and absolute time-based temporal logic operators. When using absolute time-based temporal logic operators, the SimEvents software honors the specified time delay value exactly. For example, the activation of the temporal logic 'after(3,sec)' causes the chart to wake up after three seconds of simulation clock time.

When using absolute-time temporal logic operators, observe these differences from the Stateflow® environment.



You can use as event notation in both state actions and transitions.


When you use as event notation of a transition, you cannot use additional condition notations on this transition. You can apply a connective junction to check additional conditions, as long as the connective junction has one unconditional transition.

In conditional notation, the software supports both after and before.

See Also

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