Create a Discrete-Event System Object

The MATLAB Discrete-Event System block allows you to author a custom discrete-event System object™ and use it in SimEvents^® models. To author event-driven entity-flow systems, the block uses discrete-event System object with the matlab.DiscreteEventSystem class, which inherits and extends the matlab.System class.

Methods

The matlab.DiscreteEventSystem class provides methods that let you work with these elements of a discrete-event system:

• Define properties of the object entity types, ports, and storage

  • getEntityPortsImpl — Define input ports and output ports of discrete-event system

  • getEntityStorageImpl — Define entity storage elements of discrete-event system

  • getEntityTypesImpl — Define entity types of discrete-event system

• Event initialization

  • setupEvents — Initialize entity generation events

• Runtime behavior of the object

  • blocked — Event action when entity forward fails

  • destroy — Event action upon entity destruction

  • entry — Event action when entity enters storage element

  • exit — Event action before entity exit from storage

  • generate — Event action upon entity creation

  • iterate — Event action when entity iterates

  • modified — Event action upon entity modification by the Entity Find block

  • resourceAcquired — Specify event actions upon successful resource acquisition

  • resourceReleased — Specify event actions upon successful resource release

  • testEntry — Event action to accept or refuse entity

  • timer — Event action when timer completes

While implementing these methods, define entity type, entity storage, create, schedule, and cancel events. Use these functions:

• Define entity type

  • entityType — Define entity type

• Define entity storage

  • queueFIFO — Define first-in first-out (FIFO) queue storage

  • queueLIFO — Define last-in last-out (LIFO) queue storage

  • queuePriority — Define priority queue storage

  • queueSysPriority — Define system priority queue storage

• Create events

  • eventGenerate — Create entity generate event

  • eventIterate — Create entity iterate event

  • eventTimer — Create entity timer event

  • eventForward — Create entity forward event

  • eventDestroy — Create entity destroy event

  • eventTestEntry — Create an event to indicate that the acceptance policy for the storage has changed and the storage retests arriving entities

  • eventAcquireResource — Create a resource-acquiring event

  • eventReleaseResource — Create an event to release previously acquired resources(This method allows for partial resource release)

  • eventReleaseAllResources — Create an event to release all the resources acquired by an entity

• Cancel events

  • cancelDestroy — Cancel previously scheduled entity destroy event

  • cancelForward — Cancel entity forward event

  • cancelGenerate — Cancel previously scheduled entity generation event

  • cancelIterate — Cancel previously scheduled iterate event

  • cancelTimer — Cancel previously scheduled timer event

  • cancelAcquireResource — Cancel previously scheduled resource acquisition event

• Resource Management

  • getResourceNamesImpl — Define resource pools from which the discrete-event system acquires the resources

  • resourceType — Specify an entity type and the name of the resources to be acquired by the specified entity

  • eventAcquireResource — Create a resource-acquiring event

  • eventReleaseResource — Create an event to release previously acquired resources (This method allows for partial resource release)

  • eventReleaseAllResources — Create an event to release all the resources acquired by an entity

  • cancelAcquireResource — Cancel previously scheduled resource acquisition event

  • resourceSpecification — Specify the type and amount of resources for eventAcquireResource or eventReleaseResource requests

  • initResourceArray — Initialize a resourceSpecification array, required for code generation

  • resourceAcquired — Specify event actions upon successful resource acquisition

  • resourceReleased — Specify event actions upon successful resource release

Inherited Methods from matlab.System Class

Inheriting matlab.DiscreteEventSystem class also inherits a subset of the matlab.System class methods.

getHeaderImpl	Header for System object display
getPropertyGroupsImpl	Property groups for System object display
isInactivePropertyImpl	Inactive property status
validatePropertiesImpl	Validate property values
processTunedPropertiesImpl	Action when tunable properties change
getNumInputsImpl	Number of inputs to step method
getInputNamesImpl	Names of System block input ports
getNumOutputsImpl	Number of outputs from step method
getOutputNamesImpl	Names of System block output ports
getDiscreteStateImpl	Discrete state property values
setupImpl	Initialize System object
resetImpl	Reset System object states
releaseImpl	Release resources
loadObjectImpl	Load System object from MAT file
saveObjectImpl	Save System object in MAT file
infoImpl	Information about System object
getOutputSizeImpl	Sizes of output ports
getOutputDataTypeImpl	Data types of output ports
isOutputComplexImpl	Complexity of output ports
getDiscreteStateSpecificationImpl	Discrete state size, data type, and complexity
getIconImpl	Name to display as block icon
getSampleTime	Query sample time

For more information about these methods, see Customize System Objects for Simulink.

Reference and Extract Entities

1. When referencing entity attributes or system properties in a discrete-event System object, use these formats:

   Attribute or Property	Format	Access
   attribute	entity.data.attribute_name	Read/write
   priority property	entity.sys.priority	Read/write
   ID property	entity.sys.id	Read-only

2. If an entity that is a part of a MATLAB Discrete-Event System block is requested for extraction, the exit method of the block is triggered. When the exit method is called, its destination argument is set to extract. See modified for entity modification.