MATLAB SIMEVENTS RELEASE NOTES Betriebsanweisung PDF herunterladen (Seite 65)

Key Concepts in SimEvents Software

2-43

Key Concepts in SimEvents Software

In this section...

“Meaning of Entities in Different Applications” on page 2-43

“Entity Ports and Paths” on page 2-43

“Data and Signals” on page 2-44

Meaning of Entities in Different Applications

An entity represents an item of interest in a discrete-event simulation. The meaning

of an entity depends on what you are modeling. In this chapter, examples use entities

to represent abstract customers in a queuing system and data packets from a remote

controller to an actuator on the system being controlled.

Entities do not have a graphical depiction in the model window the way blocks, ports,

and connection lines do.

Entity Ports and Paths

An entity output port provides a way for an entity to depart from a block . An entity

input port provides a way for an entity to arrive at a block.

A connection line indicates a path along which an entity can potentially advance.

However, the connection line does not imply that any entities actually advance along that

path during a simulation. For a given entity path and a given time instant during the

simulation, any of the following could be true:

• No entity is trying to advance along that path.

• An entity has tried and failed to advance along that path. For some blocks, it is

normal for an entity input port to be unavailable under certain conditions. This

unavailability causes an entity to fail in its attempt to advance along that path, even

though the path is intact (that is, even though the ports are connected). An entity that

tries and fails to advance is called a pending entity.

• An entity successfully advances along that path. This occurs only at a discrete set of

times during a simulation.

Note: The simulation could also have one or more times at which one or more entities

successfully advance along a given entity path and, simultaneously, one or more different

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MATLAB SIMEVENTS RELEASE NOTES Betriebsanweisung Seite 65