Resource entities can be generated by an Entity Generator block as regular entities are. The Name field in the EntityType tab in the block properties dialog box for an Entity Generator block lists all the entity types defined by Simulation Studio and also those defined by the user on the simulation model under investigation. (See Figure 9.4.) The list includes DefaultResourceEntity type for resource entities by default. Choose this entity type and set the desired initial units count to direct the Entity Generator to create default resource entities accordingly. The resource state of all new resource entities is Functional. The default ResourceUnits value is 1.0, but it can be changed to any nonnegative value.

New types of resource entities can be defined by the Entity Types dialog box associated with each model and later used by Entity Generator blocks. See Chapter 8: Entities, for more information about this topic.

Resource entities can also be created by the Resource Pool and Release blocks as a result of splitting other resource entities. Sometimes it is convenient to create a small number of resource entities, each with a large unit value, and store these resource entities in a Resource Pool block with the merging/splitting units option enabled. When a request for a small number of resource units is made, the Resource Pool splits the desired amount of units from the large resource units and creates new resource entities of the original types to satisfy the request.

Similarly, a Release block can split units from a resource entity and allocate the split units to a newly created resource entity (of the same type) that is then released. Additional information about merging and splitting of resources is provided later in this chapter.

Although resource entities can also be cloned with the Clone block, it is usually not recommended. The Clone block clones the attributes from the original entity, but it might ignore other run-time information, for example, the resource state and seize/unseize status that is set by the resource management blocks.

Note that creating resource entities with the Entity Generator and Clone blocks affects the total resource capacity, but doing so with the Resource Pool and Release block does not.