Entries more than the Max Content in a processor

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Shinya O asked Apr 11, '23 Phil BoBo answered Apr 19, '23

Entries more than the Max Content in a processor

Hi,

In the following model 90s, the processor has two FlowItems even though the Max Content of the processor is one.

I know that using 0 second delays works well but I don't understand why it works.

Thanks in advance.

Entries_more_than_the_MaxContents_in_a_processor.fsm

(My software version is 22.0.11, but I chose 22.0.16 because I can't select it from the pull-down menu.)

Software Version:

FlexSim 22.0.16

wait for event processors

1681207345137.png (240.3 KiB)

entries-more-than-the-maxcontents-in-a-processor.fsm (31.3 KiB)

· 1

Jeanette F ♦♦ commented · Apr 19, 2023 at 07:29 PM

Hi @Shinya O, was Joerg Vogel's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

If we haven't heard back from you within 3 business days we'll auto-accept an answer, but you can always unaccept and comment back to reopen your question.

0 ·

Answer 1 · 2023-04-19T19:38:55Z

Phil BoBo answered Apr 19, '23

This is how event listening works. The Wait For Event is spawning a token immediately during the line of code that is executing the event (in this case, an item leaving the processor and updating its content). That event may have other code that needs to finish before it is ready to start doing other things. Use a 0-time Delay activity to let the event finish before creating items that will then attempt to enter the object. As your model is configured right now, the object hasn't finished leaving the processor when you create another object to enter it. It needs to finish the logic of the leaving item so that the logic for an entering item works properly. That's what a Breathe activity does. The Wait for Event and Event-triggered Source activities often need a 0-time delay activity afterwards in order for the objects' internal logic to work correctly.

See Using Delays as Breathes and Add Breathe Activities to the Process Flow.

Answer 2 · 2023-04-11T12:15:18Z

Joerg Vogel answered Apr 11, '23

I think the engine works like this:

A standard engine process loads inputs from a state map as a copy, processes them, updates state map.

A process flow acts like an interrupt. A delay activity breaks an interrupt execution and place it at the end of currently executed engine process. Without moving an interrupt sub process to the end, the copy of the state map is not updated and the engine works with a faulty state map.

Whenever you need to overrule a return value in a model Process Flow must be executed immediately. Developers have to decide which design they prefer: immediate interrupt execution or execution of an enclosed code block in strict sequences.

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