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.

Graphical representation of a MATLAB Discrete-Event System with System Object name myDES inheriting from the matlab.DiscreteEventSystem class that, in turn, inherits from 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

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
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.