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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.

related topics

• compose architectures visually
• implement component behavior using simulink
• implement component behavior using stateflow charts