Drop-off

The Drop-off Object enables Carrier Items to release one or more of the items they are carrying.

DropOff Objects can be classified as “Logical with Capacity”, as they can hold items, and no time passes when they process items.

The DropOff can be used when modelling situations where items move or are supplied in groups or batches.

A Carrier Item carrying items can enter the DropOff, deposit some or all of the items being carried and then immediately leave the DropOff.

An item will only be delivered to a DropOff if its Class has a path leaving the DropOff.

Dropped items immediately leave the DropOff if they are not blocked.

Carrier Items pick up items using the PickUp Object.

DropOff States

  Empty  The DropOff Object is empty.

A Carrier Item carrying items may enter and restock the DropOff Object.

The Carrier Item leaves immediately after.

  Busy  The DropOff Object contains some items.

These will move out of it as soon as possible.

  Full  The DropOff Object has been stocked to its capacity.

Carrier Items cannot enter until some capacity is released (by items leaving)

  Blocked  The Carrier Item is being blocked from leaving the DropOff Object.

A queue or dispatcher should be added to the Carrier Item's Path after the DropOff to avoid this state occurring, because while the Carrier Item is blocked, no Items can leave the DropOff Object.

DropOff Properties

Capacity

Sets the maximum number of items the DropOff can hold at one time.

You can use an Attribute to set or alter a DropOff's capacity.

Selecting Capacity in the DropOff Object Menu brings up an Attribute selection dialog.

Max Qty. Dropped

This is a "per delivery" limit on the number of items a Carrier Item can drop into the DropOff Object at one time.

The default value is <no limit>. This indicates that the Carrier Item can deposit into the DropOff all qualifying items it is carrying (up to the DropOff's capacity limit).

When you select "Maximum Qty dropped", you are prompted to select an Attribute " for it.

If you use a Constant Attribute to set the per-delivery maximum value, then every Carrier Item visiting the DropOff must comply with this per-delivery maximum value, and it will not vary during the course of a model run.

To reset the <no limit> value for the DropOff, select the Constant Option in the Attribute Selection Dialog, and type in "-1".

If you use another type of Attribute to set the per-delivery maximum value, then every time that Attribute is changed during the course of a model run, the per-delivery maximum value will change also.

If you use an Item Attribute to set the per-delivery maximum value, then every time a Carrier Item goes to enter the DropOff, the Attribute is read by the DropOff and the per-delivery maximum value will be set to that value. Every agent that will use this DropOff must carry the Item Attribute.

Drop Item Flag

This is a control property that is set on to items being carried by a Carrier Item.

The Attribute Selection Dialog can be used to assign an Attribute. If for an incoming item this attribute is set to a value greater than zero, the item can be dropped (providing that there is an outgoing path from the DropOff for that item class).

The "drop item flag" feature can be used at a given DropOff Object even if some item classes dont have the "drop" attribute defined. As long as there isn't an outgoing flow for that item class, an error wont be produced.

Refer to Editing Object Properties for information about editing properties common to all objects.