Page 188 - ExtendSim User Guide
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162 Routing
Items going to several paths
type A is filled at Machine 3). Different methods of routing items to parallel processes are described in detail throughout this chapter. See also “Processing in parallel” on page 180.
• Forsituationswhereoneitemisunbatchedorseparatedintoitscomponentitems,usethe Unbatch blocks. For example, you might receive a shipment of furniture consisting of 8 desks, 20 chairs, and 7 typewriter returns, or a mail cart with 1000 pieces of mail. You use an Unbatch block to disassemble that item into its individual components, then route the items to appropriate destinations, as described in “Unbatching” on page 215.
• Toselectthepathanitemshouldgoon,usetheSelectItemOutorThrowItemblocks.The Select Item Out block is useful for routing a stream of items to several paths based on some decision. For instance, you can send all the parts that need rework to a rework station, and ship the remaining parts. Or direct patients requiring immunizations to the Injection Clinic. The use of these blocks is described in “Sequential ordering” on page 166, “Explicit order- ing” on page 167, “Routing decisions based on Item properties” on page 168, and “Select Item Out dialog” below.
Select Item Out dialog
The Select Item Out block is appropriate for routing items onto one path or another. Its dialog contains several options for determining which route an item should take.
Selection options
The logic in the dialog of the Select Item Out block chooses which output connector an input item should be routed to. The selection options are:
• Property.Theappropriateoutputisdeterminedusingtheitem’sproperty–itsattributeorpri- ority. Values to represent the outputs are entered in the table’s Select Output column; the default is that 0 selects the top output. For each item, the block finds the value of the speci- fied property in the table’s second column (which is named for that property), and deter- mines the corresponding output connector for that value in the Select Output column. Since the block will hold the item until there is downstream capacity, this option can cause block- ing.
• Connectorpriority.Anattemptismadetosendtheitemouteachconnector,intheorderof the connector’s priority, until the item is accepted by a connected block. The priority for each connector is entered in a table in the block’s dialog. The top priority is the lowest num- ber, such that an output with a priority value of 1 has a higher priority than an output with a priority value of 3.
☞ Note that this is different from assigning a priority to an item and selecting the output based on the item’s priority, as can be done with the block’s Property option. With the Connector pri- ority option, the Select Item Out block essentially prioritizes the output path, not the item.
• Random.Outputsareselectedrandomlybasedonsettingsintheblock’sprobabilitytable. Enter probabilities in decimal format. For example, enter 0.75 for 75%. If the entered num- bers do not equal 1.00, the actual sum will appear in red in the bar below the Probability col- umn. When the option If output is blocked: item will try unblocked outputs is chosen, the block will randomly try to find an output that can accept the item. When If output is blocked: item will wait for blocked output is used, the block will select an output and the item will wait until that output is able to accept the item; this can cause blocking.
Discrete Event

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