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Amanda Prado avatar image
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Amanda Prado asked Amanda Prado commented

Event-Triggered Source doesn´t work well

Doubt - Event Triggered Source.fsmHello Community,

I am in the early stages of developing a production line supply model and I am facing a dificult with my event triggered source. The ideia is:

At the beginning of the shift, each station in the production line is supplied by a source from the 3D model. This supply occurs in bins. Each station is represented by a processor. Each processor has its own processing time, based on the quantity of items in each bin + the product's cycle time.

The system works with 2 bins, that is, whenever one bin runs out, another must be replenished.

I then thought about WHEN THE CONTENT OF THE QUEUE THAT PRECEDES THE PROCESSOR REACHES 1, then a token is created in the PF to start the AGV transport process.

Does anyone have an idea of a better way to do this or guide me as to why two tokens are being created in my source?


The model is attached.


I tried hard to understand the ready-made template on material replenishment that exists, but I was unable to understand how it works. I would like to take this opportunity to see if anyone has a step-by-step guide on how to use the template. It would be fantastic.


Thank you very much in advance.



FlexSim 24.2.1
material flowreplanishmentbinevent triggerd
doubt-event-triggered-source.fsm (31.7 KiB)
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1 Answer

Logan Gold avatar image
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Logan Gold answered Amanda Prado commented

Hi @Amanda Prado, the reason you are seeing two tokens is because of the order of events when the model is first started. Even though Source1 is creating 2 items at the same time (time 0), each item is still created one at a time. The first item goes through a few different events in 0 time before the second item is created.

So the first item is created at time 0. It goes to Queue2 and the content of Queue2 increases to 1. Since the Event-Triggered Source is waiting for the content of Queue2 to arrive at a value of 1, a token is created. The item then goes to PN_A, and the content of Queue2 goes back to 0. All of these events happen in 0 time.

Then, the second item is created (still at time 0). It goes to Queue2 and the content of Queue2 increases to 1. This triggers the Event-Triggered Source, and a second token is created. The second item will now wait in Queue2 until the first item finishes in PN_A.

It sounds like you only want to start this process one time, the AGV transport process, when the triggering event happens. And then you want to wait until that process finishes before it can start again. If that is the case, then you could just use a Zone with a Max Content of 1 to only allow one token at a time to start the AGV transport process. Please let me know if I am misunderstanding that part of the model though.

You may also want to use a different Change Rule in the Event-Triggered Source, "Decrease To Exact Value". I'm guessing you only want the process to start if the content of Queue2 decreases to 1. Currently, it can happen any time an item enters an empty Queue2, but it seems like you only want it to start the replenishment processes when the content starts off higher and deceases to 1 (or whatever you want the replenishment level to be). Again, please let me know if I am misunderstanding.

What is the material replenishment template you are trying to understand? I don't think I'll have a step-by-step guide for you, but I can try to give you some tips/hints if you tell me what model you're working on.

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Amanda Prado avatar image Amanda Prado commented ·

Hello Logan,

I understood perfectly the explanation about the reason for creating 2 tokens at time 0. Doubt cleared.

Regarding your suggestion to create a token when the content decreases to 1, I tried, but at least for me, it doesn't work. No token is created.

Let me explain what I'm trying to do:

Small materials are paid in "bins", at the beginning of production, 2 bins are made available to the stations. As production progresses, the items are reduced. Whenever i newt reaches 1 bin, a message is sent to another sector that prepares another bin, at the same time that it triggers a message for the AGV to collect this bin + other bins that may be ready and make them available at a central point of the line.


The replenishment model I mentioned is the ready template of the Process Flow.


Thank you so much!!!

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Emily Hardy avatar image Emily Hardy ♦ Amanda Prado commented ·

The issue is that the queue is sending the 1st box to the processor PN_A before the second box enters the queue, so the content of the queue is never more than 1.

To fix this, I added a trigger that closes the output of the queue On Reset. Then, in Process Flow, I added a flow where a token will wait 0 seconds and then open the queue output. This will ensure that the queue counts both items and allows the Event Triggered Source to work correctly.

doubt-event-triggered-source_EditedEH.fsm

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doubt-event-triggered-source-editedeh.fsm (33.4 KiB)
Amanda Prado avatar image Amanda Prado Emily Hardy ♦ commented ·
Thank you very much, Emily !
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