Active state data can simplify the design of some Stateflow® charts because you do not have to maintain data that is highly correlated to the chart hierarchy. When you enable active state data, Stateflow reports state activity through an output port to Simulink® or as local data in your chart. Using active state data, you can:
Avoid manual data updates reflecting chart activity.
View chart activity by using a scope or the Simulation Data Inspector.
Log chart activity for diagnostics.
Drive other Simulink subsystems.
When you enable active state data, Stateflow creates a Boolean or enumerated data object to match the activity type.
|Activity Type||Active State Data Type||Description|
|Self activity||Boolean||Is the state active?|
|Child activity||Enumeration||Which child is active?|
|Leaf state activity||Enumeration||Which leaf state is active?|
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.
|Stateflow Object||Self-Activity||Child Activity||Leaf State Activity|
|Atomic subcharts||Supported at the container level||Supported inside the subchart||Supported inside the subchart|
|State transition tables||Not supported||Supported||Supported|
You can enable active state data in either the Property Inspector or the Model Explorer.
Open the Property Inspector by selecting View > Property Inspector.
In the Stateflow Editor canvas, select the Stateflow object to monitor.
In the Monitoring section of the Property Inspector, select the Create output for monitoring check box and edit the active state data properties.
Open the Model Explorer by selecting View > Model Explorer.
In the Model Hierarchy pane, double-click the Stateflow object to monitor.
In the Stateflow object pane, select the Create output for monitoring check box and edit the active state data properties.
Type of state activity to monitor. Choose from these options:
Leaf state activity
Name of the active state data object. For more information, see Rules for Naming Stateflow Objects.
Name of the enumerated data type for the active state data object. This property applies only to child and leaf state activity.
Specifies whether you define the enumerated data type manually. This property applies only to child and leaf state activity. For more information, see Define State Activity Enumeration Type.
By default, active state data has a scope of
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
window 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
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
gear_state contains four child states that correspond
to the gears in a car:
fourth. The model specifies the
child activity data type with this enumeration class
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).
When you enable leaf state activity, a state with parallel (AND) decomposition is
treated as a leaf state. State activity of the parallel substates is not available
because these substates are active simultaneously. For example, suppose that you
enable leaf state activity for this chart. Because state
parallel decomposition, its substates
B2 are active simultaneously so
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
Enabling child activity output for states that have no children results in an error at compilation and run time.
You cannot enable child or leaf state activity in charts or states with
parallel decomposition. To check state activity in substates of parallel
states, use the
in operator. For more information, see
Check State Activity by Using the in Operator.
Do not select the chart property Initialize Outputs Every Time Chart Wakes Up on charts that use active state output data. With this setting, the behavior of the output data is unpredictable.