Implement Component Behavior Using Activity Diagrams

An activity diagram describes system behavior that helps visualize the functional flow of a system through actions or decisions. Activity diagrams can help you understand how system components interact with one another. For more information, see Describe System Behavior Using Activity Diagrams.

You can add activity diagram behavior for components within System Composer™ to describe or specify flow-based behavior using nodes, pins, and flows. You can also reference an activity diagram within a Simulink^® model using a Model block.

This topic uses the RobotActivity activity diagram from the scMobileRobotExample project to show how to:

• Create a System Composer component.

• Create a new activity diagram behavior for a System Composer component.

  • Link to an existing activity diagram.

  • Create a new activity diagram behavior.

• Simulate component with activity diagram behavior.

Create Component

To create an activity diagram behavior, you can use an existing component or create a component. To create a new component:

1. At the MATLAB^® Command Window, enter this command.

   systemcomposer

   Select Architecture Model.

2. On the Simulation tab, select New , and then select Architecture .

3. Left-click and drag a component from the palette and release the mouse button to commit.

4. To change the name of the component, click the component, and then click its name. Change the name to MobileRobot.

Note

You cannot create activity behavior for a component that has existing ports or subcomponents.

Create Activity Diagram Behavior

You can link a System Composer block to an existing activity diagram model. For this subsection, you can use the RobotActivity activity diagram from the scMobileRobotExample project. Open this project using the following example.

openExample('systemcomposer/OpenActivityDiagramForRobotExample');

Link to an Existing Activity Diagram

To create activity diagram behavior for the RobotActivity component, take one of these two actions: right-click menu and toolstrip.

To create activity diagram behavior for the RobotActivity component, take one of these actions:

• Right-click the component MobileRobot and select Create Behavior > Create Activity Diagram Behavior. This action opens a new activity diagram behavior canvas.

• From the toolstrip, on the Modeling tab, click the down arrow in the Component section, and then select Create Activity Diagram Behavior.

The Create Activity Diagram behavior dialog box opens. In the New file name box, enter RobotActivity. To create a data dictionary for the new component, select Create a local dictionary for the new component. In the Name box, enter the data dictionary as MobileRobot_dict.sldd.

To create the new activity diagram behavior, click OK.

Create a New Activity Diagram Behavior

You can also link to an existing activity diagram behavior model. For this example, use the RobotActivity model.

• Right-click the MobileRobotcomponent and select Link to Model.

• Type or browse for the name of an activity diagram model. For this example, enter RobotActivity.slx.

• To create the link, click OK.

The component displays input and output ports that correspond to the parameter nodes within the activity diagram. The input and output ports can accept data in the form of a signal or message. You can specify the mode of data that is accepted by setting the Data Mode parameter of a Parameter Node.

The icon on the top-right corner of the component represents an activity diagram behavior.

To add or remove the model preview, right-click and select Format > Content Preview.

Simulate Component with Activity Diagram Behavior

For a component with activity diagram behavior, simulation behavior depends on whether the activity diagram contains an initial node or an input parameter node.

• For activity diagrams with an initial node, the simulation starts at time zero. For activity diagrams with an input parameter node, the simulation begins as soon as the input parameter node receives a token.

• The simulation of an activity diagram component ends when the activity final node or the output parameter node receives a token. The time it takes for the activity final node or the output parameter node to receive a token depends on the duration property of the nodes within the activity diagram.

Set Up Input Parameter Node

The component displays input and output ports that correspond to the parameter nodes within the activity diagram. The input parameter node can accept data in the form of a signal or message. To specify the type, right-click the input parameter node. In the Property Inspector, set the Data Mode to either message or gignal. The default value is signal.

Use these options to set the type of communication in the system. A signal represents a continuous flow of data at each simulation time step between components.

Messages are used to model asynchronous communication and event-driven systems. For more information on modeling messages, see Simulink Messages Overview.