Page 283 - ExtendSim User Guide
P. 283

Resource orders
If each item could only have one resource requirement, and if each resource requirement could only be selected by one item, statistical information could be obtained just from the resource requirement’s usage. Instead, the ARM system allows each item to have multiple resource requirements and even the same resource requirement multiple times but at different Queues. Additionally, several different items can each have the same resource requirement. To track data and calculate statistical information, the ARM system uses resource orders.
A resource order is the association of a particular item with a specific resource requirement; it is represented by a unique Resource Order ID (discussed on “Item properties” on page 260). Resources are allocated to orders and each item can have multiple resource orders.
When an item gets to a Queue, the Queue makes a request to the Resource Manager for the resources specified by the item’s resource requirement. The Resource Manager then:
• Convertsthatrequestintoaresourceorder
• Creates a corresponding record in the Resource Orders table that refers to the resource request and identifies which Queue the order came from, when it was ordered, and so forth
• Assigns a Resource Order ID to the item
• Attemptstosatisfytheitem’sresourcerequirement
• When a resource is successfully assigned to an item, the Resource Order ID field in the Resources table is updated. That information is used to track the resource’s last allocation.
This architecture allows the ARM system to track data and calculate statistical information such as when a resource was requested and the average length of time it took to satisfy.
For more detailed information, see “Primary transactions for ARM” on page 272.
Status and transitions
A resource’s status provides information about its current state. The status usually changes dynamically during a simulation run. Resources can have any one of five different status set- tings:
1) Idle
2) Busy
3) OffShift 4) Down
5) Disabled
Idle or Disabled can be set as the initial status when the resource is created or edited. Busy is a function of the resource’s use in the model. Off Shift and Down are controlled by the Shift and Shutdown blocks (Item library), respectively. The Resource Manager’s Results tab gives infor- mation about the amount of time each selected resource was busy, idle, and so forth.
Except that a resource cannot transition from disabled to down, each status can transition to any of the others. This gives a total of nineteen status transitions. To track status transactions, check Resource status transition in the transaction type table on the Resource Manager’s Event Logging tab.
Resources and Shifts 257
Additional information
Discrete Event


































































































   281   282   283   284   285