Page 451 - ExtendSim User Guide
P. 451

Mixing Flow and Items 425
Using the Interchange block to mix items with flow
• The item input and item output connectors on the Interchange block must both always be connected.
• At least one of the Interchange block's inflow/outflow connectors must be connected (both may be connected as well).
• TheInterchangeblock'scapacityforholdingitemsispermanentlyfixedatoneitem.
• The Interchange block loads and unloads the item and its flow instantaneously. (Flow pres- ent in the item when it enters the block is instantaneously available to the block; flow leav- ing the block with an item is instantaneously removed from the block.)
The flow connector configuration
The behavior of the Interchange
block is dramatically affected by
how the inflow and outflow con-
nectors have been connected. As
mentioned above, only one of the
two flow connectors needs to be
connected. If only the inflow con-
nector is connected, arriving items
can only be filled with flow, and if only the outflow connector is connected, arriving items can only unload flow.
Item release conditions
The release conditions determine when an item is scheduled to leave the Interchange block; they are the same for both block modes. Releases can also be accomplished at any time using the Preempt connector.
Arriving item is always filled (left) or is always emptied (right)
Scheduled releases
There are 5 options for defining when the item should be released:
• Whencontents>=Target.Thisoptionrequiresthe item to be filled with a certain amount of flow prior to release. The Target amount is entered in the dialog.
• Whencontents<=Target.Requirestheitem'sflow level to empty to a certain point prior to release. The Target amount is entered in the dialog.
Release options for Interchange block
• As soon as possible. Releases the item whenever there is downstream item capacity for the item, irrespective of the current flow level.
• Onlywithpreemptconnectormessage.Releasestheitemwhenatruevalueisreceivedatthe block’s PE (preempt) value input connector.
• When level reaches indicator. Requires the flow contents to reach a certain level prior to release. Indicators (segments that indicate the level of contents) must first be entered on the block’s Indicator tab for this option to be used.
Discrete Rate

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