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What Do Semantics Mean for Stateflow Charts?

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What Are Chart Semantics? Common Graphical and Nongraphical Constructs References for Chart Semantics

What Are Chart Semantics?

Chart semantics describe execution behavior according to the interaction of graphical and nongraphical constructs.

Graphical Constructs

Graphical constructs consist of objects that appear graphically in a chart. You use the object palette in the Stateflow Editor to build graphical constructs (see Using the Stateflow Editor).

Graphical Constructs	Types	References
Flow graphs	Decision logic patterns Loop logic patterns	Modeling Logic Patterns and Iterative Loops Using Flow Graphs
Functions	Graphical functions Embedded MATLAB functions Truth table functions Simulink functions	What Is a Graphical Function? Introduction to Embedded MATLAB Functions What Is a Truth Table? What Is a Simulink Function?
Junctions	Connective junctions History junctions	Connective Junctions History Junctions
States	States with exclusive (OR) decomposition States with parallel (AND) decomposition Substates and superstates	Exclusive (OR) State Decomposition Parallel (AND) State Decomposition Creating Substates and Superstates
Transitions	Default transitions Object-to-object transitions Inner transitions Self-loop transitions	Default Transitions Transition Connections

Nongraphical Constructs

Nongraphical constructs appear textually in a chart and often refer to data and events (see Defining Data and Defining Events). You follow syntax rules of the Stateflow action language to build nongraphical constructs (see Using Actions in Stateflow Charts).

Examples of nongraphical constructs include:

• Conditions and condition actions

• Function calls

• State actions

• Temporal logic statements

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Common Graphical and Nongraphical Constructs

The following chart shows commonly used graphical and nongraphical constructs.

Chart Construct	Graphical or Nongraphical?	Description	Reference
Condition	Nongraphical	Boolean expression that specifies that a transition path is valid if the expression is true; part of a transition label	Transition Label Notation and Conditions
Condition action	Nongraphical	Action that executes as soon as the condition evaluates to true; part of a transition label	Transition Label Notation and Condition Actions
Connective junction	Graphical	Object that enables representation of different possible transition paths in a flow graph	Connective Junctions
Default transition	Graphical	Object that specifies which state to enter when two or more exclusive (OR) states exist at the same level of hierarchy	Default Transitions
Embedded MATLAB function	Graphical	Method of performing computations using a subset of the MATLAB language	Using Embedded MATLAB Functions in Stateflow Charts
Flow graph	Graphical	Construct that models logic patterns by using connective junctions and transitions	Modeling Logic Patterns and Iterative Loops Using Flow Graphs
History junction	Graphical	Object that remembers the previously active state at the level of hierarchy in which it appears	History Junctions
State actions	Nongraphical	Expressions that specify actions to take when a state is active, such as initializing or updating data; part of a state label	State Labels and State Action Types
State with exclusive (OR) decomposition	Graphical	State where no more than one substate can be active at a time	Exclusive (OR) State Decomposition
State with parallel (AND) decomposition	Graphical	State where all substates can be active at the same time	Parallel (AND) State Decomposition
Substate	Graphical	State that resides inside another state	Creating Substates and Superstates
Superstate	Graphical	State that contains one or more states	Creating Substates and Superstates
Transition guarded by input event	Graphical	Decision path that occurs if the chart receives a specific event broadcast from another block in the model	Transition Action Types

For details on how these graphical and nongraphical constructs interact during chart execution, see How Chart Constructs Interact During Execution.

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References for Chart Semantics

For detailed information on types of chart semantics, see these references.

Topic	Reference
How do events affect chart execution?	How Events Drive Chart Execution
How does a chart switch between being active and inactive?	Types of Chart Execution
In what order do flow graphs execute?	Process for Grouping and Executing Transitions
In what order do outgoing transitions from a single source execute?	Evaluation Order for Outgoing Transitions
What happens when you enter, execute, or exit a state?	Process for Entering, Executing, and Exiting States
How do parallel (AND) states work?	Execution Order for Parallel States
How does early return logic affect chart execution?	Early Return Logic for Event Broadcasts

For detailed examples of chart semantics, see Semantic Examples.

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Stateflow Chart Semantics

How Chart Constructs Interact During Execution

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