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Describe System Behavior Using Sequence Diagrams

A sequence diagram represents the expected interaction between structural elements of an architecture as a sequence of message exchanges.

Use sequence diagrams to describe how the parts of a system interact.

Sequence diagrams are integrated with architecture models in System Composer™.

A lifeline is represented by a head and a timeline that proceeds down a vertical dotted line.

The head of a lifeline represents a component in an architecture model.

A message sends information from one lifeline to another. Messages are specified with a message label.

A message label has a trigger and a constraint. A trigger determines whether the message occurs. A constraint determines whether the message is valid.

An annotation describes the elements of a sequence diagram.

Use annotations to provide detailed explanations of elements or workflows captured by sequence diagrams.

A fragment indicates how a group of messages within it execute or interact.

A fragment is used to model complex sequences, such as alternatives, in a sequence diagram.

An operand is a region in a fragment. Fragments have one or more operands depending on the kind of fragment. Operands can contain messages and additional fragments.

Each operand can include a constraint to specify whether the messages inside the operand execute. You can express the precondition of an operand as a MATLAB® Boolean expression using the input signal of any lifeline.

Author sequence diagrams labeled.

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