Page 424 - ExtendSim User Guide
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Merging, Diverging, and Routing Flow
Throwing flow and catching flow remotely
the chosen set of parameter values remains unchanged for the duration of the goal, effective rates are recalculated only at the beginning of each new goal.
3) BycheckingPollnewparametersonlyeach:xtimeunitsintheblock’sOptionstab. This causes a new set of parameters to be updated at fixed intervals. In this case, changes to the inputs are ignored until the next interval in time arrives. In the example “Change Pro- portions Periodically”, the model picks a new set of proportions every time another 100 units of time is reached.
☞ The options Update only when a True value is received at the Update connector and Poll new parameters only each: x time units can be combined together.
Throwing flow and catching flow remotely
The most common way to route flow from one block to another is by drawing a connection from an outflow connector to an inflow connector. This is a powerful mechanism for routing flow because it's simple to implement and it provides a very clear picture of how the flow is being routed in a model. The use of connection lines between connectors, however, can prove to be cumbersome when many streams of flow need to be routed into or out of hierarchical blocks.
The ExtendSim throw/catch mechanism solves this issue by allowing flow to be moved with- out the use of connection lines. By creating a throw/catch connection via block dialogs, flow can be routed from a throwing block to any catching block in the model.
In the Rate library:
• Flow can be sent from the Throw Flow and Diverge blocks
• Flow can be received by the Catch Flow and Merge blocks.
• Any sending block can throw to any catching block regardless of location.
The rules restricting how normal flow connections can be drawn between outflow and inflow connectors also apply to throw/catch connections:
• The flow can go one way only – from throw to catch
• One throw can be connected with one and only one catch • One catch can be connected with one and only one throw
☞ The advantage of using a Diverge block to throw flow or a Merge block to catch flow, is that each outflow or inflow branch can throw or catch a separate stream of flow remotely. The Throw Flow and Catch flow blocks, on the other hand, are limited to one flow source or desti- nation each.
Discrete Rate

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