Page 198 - ExtendSim User Guide
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172 Routing
Items going to several paths
Buffering Operations model
A model with queues before each operation could look like:
Buffering Operations model: Parallel processing with buffering
In the model, the queues have a maximum queue length of 30 each. The first queue that was connected will receive all the items until that queue reaches its maximum, then the next queue will start to fill (unless the first machine kept up with the flow of items, in which case the next queue will never receive any items). In the Buffering Operations model, for example, most of the items go to the top queue and get processed by Machine 1 and none of the items go to the bottom queue to be processed by Machine 3. This is rarely what you want.
To even out the use of the machines, use a Select Item Out block set to select machines sequen- tially, as shown in the “Sequential Ordering model” on page 167, and place a queue before each machine. Note however, that if the machines work at different speeds, this will cause the queue of the slowest machine to fill more rapidly than the other queues.
☞ A green bar across its top indicates that a Queue is set to something other than infinite capacity. For instance, the Queues in this model are set to hold a maximum of 30 items and therefore have green bars across their tops.
Output Line Balancing model
A better method than the Buffering Operations example would be to check the length of the waiting line in each queue and give the next item to the queue that is shortest, causing the
Discrete Event

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