Documentation

Types of Active State Data

When you enable active state data, Stateflow creates a Boolean or enumerated data object to match the activity type.

For self-activity of a chart or state, the data value is true when active and false when inactive. For child and leaf state activity, the data is an enumerated type. Stateflow can define the enumeration class or you can create the definition manually. For more information, see Define State Activity Enumeration Type.

You can enable active state data for a Stateflow chart, state, state transition table, or atomic subchart. This table lists the activity types supported by each kind of Stateflow object.

Enable Active State Data

You can enable active state data in either the Property Inspector or the Model Explorer.

Active State Data Properties

Set Scope for Active State Data

By default, active state data has a scope of Output. Stateflow creates an output port on the chart block in the Simulink model.

To access active state data inside a Stateflow chart, change the scope to Local in the Symbols pane or in the Model Explorer. For more information, see Set Data Properties.

You can specify information for code generation by binding the local active state data to a Simulink.Signal object. Modify the properties of the object through the CoderInfo property. For more information, see Simulink.CoderInfo.

Define State Activity Enumeration Type

By default, Stateflow defines the enumeration data type for child and leaf activity. If you select the Define enumerated type manually check box and no enumeration data type definition exists, then Stateflow provides a link to create a definition. Clicking the Create enum definition from template link generates a customizable definition.

The enumeration data type definition contains one literal for each state name plus an extra literal to indicate that no substate is active. For example, in the model sf_car, the state gear_state contains four child states that correspond to the gears in a car: first, second, third, fourth. The model specifies the child activity data type with this enumeration class definition:

classdef gearType < Simulink.IntEnumType
   enumeration
		None(0),
		first(1),
		second(2),
		third(3),
		fourth(4)
   end
...
end

The base storage type for automatically created enumerations defaults to Native Integer. For a smaller memory footprint, in the Optimization pane of the Configuration Parameters dialog box, change the value of the Base storage type for automatically created enumerations field. For more information, see Base storage type for automatically created enumerations (Simulink Coder).

State Activity and Parallel States

In states with parallel (AND) decomposition, child activity and leaf state activity are not available because the parallel substates are active simultaneously.

When you enable leaf state activity in a chart or state, a substate with parallel (AND) decomposition is treated as a leaf state. For example, suppose that you enable leaf state activity for this chart. Because state B has parallel decomposition, its substates B1 and B2 are active simultaneously so B is treated as a leaf state of the chart.

During simulation, a scope connected to the active state output data shows the enumerated values for the leaf states A1, A2, and B.

Limitations for Active State Data