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Mask Simulink Based States

Use Simulink® based states to model hybrid dynamic systems or systems that switch between periodic and continuous-time dynamics. In your Stateflow® chart, you can combine Simulink based states with switching logic that uses transitions. For more information about Simulink based states, see Simulink Subsystems as States.

You can use masks with linked Simulink based states to control the parameters for various inputs and outputs to your system at the chart level. Masking is especially beneficial for systems that have reusable components, as it enables the customization of parameters to fit distinct scenarios or use cases. Masking allows you to reuse components while maintaining the ability to fine-tune the behavior of each instance of the Simulink based state.

This example shows how to modify a Stateflow chart to update the parameters of a Simulink based state system.

Create a Masked Simulink Based State

Open the Pole Vaulter example and its corresponding library. At the command prompt, type:


This example models a pole vaulter. For a detailed explanation of the model, see Access Block State Data.

To unlock the library, click the Locked Library button. Select the Run_up subsystem. In the toolstrip, open the Subsystem Block tab. Click the Create Mask button. The mask editor appears. For more specifics about the mask editor capabilites, see Mask Editor Overview (Simulink).

In the Controls pane, use the Promote One-to-One button and add one parameter for the velocity of the vaulter and one parameter for the starting position. To add these parameters, choose InitialCondition for both Position and Velocity.

One to one parameter promotion.

After you add the parameters, you can edit the prompt and the name.

Promote one-to-one mask editor.

The Prompt column shows the text that appears in the block dialog for the block mask. The Name column is the name of the parameter data.

Click the Save Mask button and close the mask editor. In the library, the Run_up block icon includes a gray arrow in the lower-left side. This arrow indicates that there is a mask on the block.

Masked subsystem block.

Add a Masked Subsystem to Stateflow

In the sf_pole_vault Simulink model, open the PoleVaulter Stateflow chart. Delete the Run_up Simulink based state, and replace it with the masked Run_up subsystem block from the library. The new chart shows the linked and masked Simulink based state.

Updated Pole Vaulter chart with makes Simulink based state.

To update the starting position and velocity of the vaulter, double-click the updated Run_up state. The Block Parameters window appears. In the Parameters tab, you can update the starting position and the velocity.


The starting position for the vaulter must be a negative number, because the bar is located at y = 0 in this example. Additionally, because the vaulter plants his pole at y = -4, use a number smaller than -4.

Parameter mask.

In the Mappings dialog, update the output mapping so that the Subsystem Symbol corresponds to the correct Main chart symbol.

Mappings mask.

View the Results

After running the model, open the XY Graph block.

Results of running the model.

The graph shows that the vaulter started at -15, because the velocity is 5, the vaulter did not reach a height over 1.


Masked Simulink based states do not support:

  • Self-modifiable masks.

  • Drawing Commands tab.

  • Undo or redo in the Mask Dialog.

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