Stateflow chart creation in Simulink - Step-by-Step Execution

Concept Flow - Stateflow chart creation

Start Simulink

↓

Open Stateflow

↓

Create New Chart

↓

Add States

↓

Define Transitions

↓

Set Entry/Exit Actions

↓

Add Inputs/Outputs

↓

Simulate and Test

↓

Save and Integrate

This flow shows the steps to create a Stateflow chart: start Simulink, open Stateflow, create chart, add states and transitions, set actions, add inputs/outputs, simulate, then save.

Execution Sample

Simulink

sfnew;
chart = sfroot.find('-isa','Stateflow.Chart');
state = chart.addState();
state.Name = 'Idle';
state.Position = [100 100 80 60];
chart.addTransition(state, state);

This code creates a new Stateflow chart, adds a state named 'Idle', positions it, and adds a self-transition.

Execution Table

Step	Action	Object Created/Modified	Properties Set	Result
1	Create new Stateflow chart	Chart	Default properties	Chart created and opened
2	Add state to chart	State	Name='Idle', Position=[100 100 80 60]	State 'Idle' added at position
3	Add transition from 'Idle' to 'Idle'	Transition	Source='Idle', Destination='Idle'	Self-transition added
4	Verify chart structure	Chart	Contains 1 state and 1 transition	Chart ready for simulation
5	Simulate chart	Simulation	Run with default inputs	Chart runs with 'Idle' state active
6	Save chart	File	Saved to model	Chart saved successfully

💡 All steps completed, chart created and ready for use

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
chart	None	Chart object created	Chart with 1 state	Chart with 1 state and 1 transition	Chart ready
state	None	State 'Idle' created	State unchanged	State unchanged	State unchanged
transition	None	None	Self-transition created	Transition unchanged	Transition unchanged

Key Moments - 3 Insights

Why do we need to set the position of a state explicitly?

Setting the position defines where the state appears visually in the chart. Without it, the state may overlap or be hard to see, as shown in step 2 of the execution_table.

What happens if we add a transition without specifying source and destination?

The transition will not connect states properly and may cause errors or unexpected behavior. Step 3 shows how specifying source and destination creates a valid transition.

Why simulate the chart after creation?

Simulation tests if the chart behaves as expected with the current states and transitions. Step 5 confirms the chart runs with the 'Idle' state active.

Visual Quiz - 3 Questions

Look at the execution_table, what is the name of the state created at step 2?

A Idle

B Start

C Init

D Run

💡 Hint

Check the 'Properties Set' column in step 2 of the execution_table

At which step is the self-transition added to the state?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Action' and 'Result' columns in the execution_table for the transition creation

If we skip setting the state's position, what would likely happen?

A The state will not appear in the chart

B The state will appear at a default or overlapping position

C The chart will fail to simulate

D The transition will not work

💡 Hint

Refer to key_moments about the importance of setting position and step 2 in execution_table

Concept Snapshot

Stateflow chart creation steps:
1. Open Simulink and Stateflow
2. Create a new chart
3. Add states with names and positions
4. Define transitions between states
5. Set entry/exit actions if needed
6. Simulate to test behavior
7. Save chart for use in model

Full Transcript

To create a Stateflow chart, start by opening Simulink and then the Stateflow tool. Create a new chart object. Add states by naming them and setting their positions so they appear clearly. Define transitions by connecting source and destination states. Optionally, set entry and exit actions for states. Simulate the chart to verify it behaves as expected. Finally, save the chart to include it in your Simulink model. This process helps visually design state machines for control logic.

Practice

1. What is the main purpose of creating a Stateflow chart in Simulink?

easy

A. To design graphical user interfaces

B. To model systems with different states and transitions

C. To perform numerical calculations on data arrays

D. To create 3D animations

Solution

1. Step 1: Understand the role of Stateflow charts

   Stateflow charts are used to represent systems that have multiple states and rules for moving between those states.

2. Step 2: Compare with other options

   Options A, B, and D describe tasks unrelated to Stateflow charts, which focus on state-based system modeling.

3. Final Answer:

   To model systems with different states and transitions -> Option B

4. Quick Check:

   Stateflow charts = state and transition modeling [OK]

Hint: Stateflow = states + transitions modeling [OK]

Common Mistakes:

• Confusing Stateflow with data processing blocks
• Thinking Stateflow creates GUIs
• Assuming Stateflow is for animations

2. Which of the following is the correct way to create a new state in a Stateflow chart?

easy

A. Drag a 'State' block from the Simulink library browser

B. Double-click the Simulink block to add a state

C. Use the MATLAB command addstate() in the command window

D. Right-click inside the chart and select 'Add State'

Solution

1. Step 1: Identify how to add states in Stateflow

   In Stateflow, you add states by right-clicking inside the chart and choosing 'Add State' from the menu.

2. Step 2: Evaluate other options

   Double-clicking a Simulink block or dragging blocks from Simulink library does not add states in Stateflow. The addstate() command does not exist.

3. Final Answer:

   Right-click inside the chart and select 'Add State' -> Option D

4. Quick Check:

   Add state = right-click menu [OK]

Hint: Right-click inside chart to add states [OK]

Common Mistakes:

• Trying to add states from Simulink library
• Using nonexistent MATLAB commands
• Double-clicking blocks expecting to add states

3. Consider a Stateflow chart with two states: Idle and Active. The transition from Idle to Active occurs when start == 1. If start is 0 initially and then changes to 1, what will be the active state after simulation?

medium

A. Active

B. Idle

C. Both Idle and Active

D. No active state

Solution

1. Step 1: Understand the transition condition

   The chart starts in Idle. When start == 1, it transitions to Active.

2. Step 2: Analyze the simulation behavior

   Initially, start is 0, so the chart stays in Idle. When start changes to 1, the transition triggers, moving the chart to Active.

3. Final Answer:

   Active -> Option A

4. Quick Check:

   start=1 triggers transition to Active [OK]

Hint: Transition triggers when condition true [OK]

Common Mistakes:

• Assuming state changes before condition is true
• Thinking both states can be active simultaneously
• Ignoring transition conditions

4. You created a Stateflow chart but the simulation does not switch states as expected. Which of the following is a likely cause?

medium

A. The chart has too many states

B. The Simulink model is not saved

C. Transition condition is missing or incorrect

D. The MATLAB version is outdated

Solution

1. Step 1: Identify common reasons for no state switching

   If transitions do not have correct conditions, the chart will not move between states.

2. Step 2: Evaluate other options

   Having many states does not prevent switching. Not saving the model or MATLAB version usually does not cause this specific issue.

3. Final Answer:

   Transition condition is missing or incorrect -> Option C

4. Quick Check:

   Missing transition condition blocks state change [OK]

Hint: Check transition conditions first [OK]

Common Mistakes:

• Blaming number of states for no transitions
• Ignoring transition conditions
• Assuming saving fixes simulation logic

5. You want to create a Stateflow chart that models a traffic light with states Red, Green, and Yellow. The light should cycle through these states every 5 seconds. Which approach correctly implements this behavior?

hard

A. Create states for Red, Green, Yellow with transitions triggered by a timer event every 5 seconds

B. Create one state with a variable counting seconds and use if-else inside it

C. Use Simulink blocks only without Stateflow to model timing

D. Create states but transitions happen manually by user input

Solution

1. Step 1: Understand traffic light cycle requirements

   The traffic light cycles through states automatically every 5 seconds, so timed transitions are needed.

2. Step 2: Evaluate implementation options

   Create states for Red, Green, Yellow with transitions triggered by a timer event every 5 seconds uses states and timer-triggered transitions, which fits the requirement. Create one state with a variable counting seconds and use if-else inside it uses one state and if-else, which is less clear and harder to manage. Use Simulink blocks only without Stateflow to model timing ignores Stateflow, losing state logic. Create states but transitions happen manually by user input requires manual input, not automatic cycling.

3. Final Answer:

   Create states for Red, Green, Yellow with transitions triggered by a timer event every 5 seconds -> Option A

4. Quick Check:

   Timed transitions cycle states automatically [OK]

Hint: Use timer events for automatic state cycling [OK]

Common Mistakes:

• Using manual input instead of timer events
• Trying to do all logic in one state
• Ignoring Stateflow for state-based timing