In Simulation Studio, resources are special objects that provide services or materials to entities. In some models, the available resources are unlimited; in other models, the number of units of a resource is limited. You can vary the number of available resource units during a simulation run by using a resource schedule. The availability of resources can affect the flow of entities during a simulation run.
A system that is modeled in Simulation Studio can use two types of resource objects: stationary resources and mobile resources. Stationary resources include the entity holding blocks (the Queue, Server, Delay, and Resource Pool blocks), which delay entities for some period of time during the simulation. The stationary resources are static, and they are created at model building time. Mobile resources, which are resource objects that flow in the model, are dynamic and are created during the simulation execution. Mobile resources are defined as a special type of entity. They have all of the capabilities of regular entities, but they also have additional functionality that is managed by the blocks on the Resource template. Mobile resources (in particular, resource entities and their management) are the main focus of this chapter.
Like regular entities, resource entities are objects that can carry attributes. All resource entities in Simulation Studio have a predefined entity attribute named ResourceUnits, which represents the capacity (the number of units) of the resource. Although the ResourceUnits attribute has special uses for resource entities, it can also be used as an ordinary numeric entity attribute for modeling purposes. In addition to the ResourceUnits attribute, each resource entity also has run-time state information (such as resource state and seize status) that is used by the simulation system to perform resource management during the run. The resource state can be Functional, Failed, Maintenance, or Offlined.