Processor blocked even if downstream is free

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Philip Diem asked Jun 9, '21 Philip Diem answered Jun 9, '21

Processor blocked even if downstream is free

Hi Guys.

I have a little Problem I can't wrap my head around.
The model attached is an assembly line which is part of a bigger Model im working on.

The model itself isn't that complicated. it's a a line of an assembly station, followed by two flashing stations followed by a testing station.
The operator is used for assembly and the setup of the flash as well as the testing stations.
It's completely realized with aprocess flows and lists.

The troubling part is, the Model attached works. No problem.
I developed that on its own to test it before i implement it in the bigger model.
The problem is, as soon as I implemented it in the bigger model it stopped working and I can't figure out why. As soon as the first two items are processed, the assembly station stays blocked although the downstream is free (see picture below).
at first I I copied the testing model into the bigger model and it didn't work even though i completely re-did all paramters and connections. As I figured flexim just didn't copy something that was probably neccessary I completely rebuild it in the bigger model but with the same result. It doesn't work.
I out of wit at this point. Can somone point me to a direction?

Montagetest.fsm

Software Version:

FlexSim 20.1.3

flexsim 20.1.3 processor lists blocked

1623220767598.png (165.0 KiB)

montagetest.fsm (78.8 KiB)

· 3

Begoña Espiñeira commented · Jun 09, 2021 at 10:10 AM

Hi @Philip Diem,

Can you attach the model that does not work? It is difficult to give you an answer without seeing the problem.

0 ·

Philip Diem Begoña Espiñeira commented · Jun 09, 2021 at 10:59 AM

Hi Begoña

Unfortunately I can't share the complete model, its too big and Im quite sure i would break some confidentiality rules.
But I copied the part that didn't work out of the model and now it shows the same problem.
O_o
Here you go:

example.fsm

Thanks in Advance :)

0 ·

example.fsm (74.6 KiB)

Begoña Espiñeira Philip Diem commented · Jun 09, 2021 at 01:30 PM

Thank you! I have been trying to understand why it doesn´t work. For some reason the push to list (Output) stops working. I try changuing the way you do the push. If you do the push on an On process Finish trigger (on processor properties) and you disconnect the output connections, it works because you are doing the transport by ProcessFlow. I recommend you make your model only using 3D or only using ProcessFlow because if you use both, the logics might conflict.

example_2.fsm

1 ·

1623245317423.png (50.8 KiB)

example-2.fsm (79.3 KiB)

Answer 1 · 2021-06-09T13:30:48Z

Felix Möhlmann answered Jun 9, '21

Hi @Philip Diem,

the issue in the second model is that the order in which the stations are connected to the first processor is different to the ordering within their group.

In the following screenshot, note how the input arrow of the lower station is red, although the item was transported to the upper one. That's because the processor was sending the item out through its first port (first available) but that got overridden by the process flow, where the other station was acquired (due to order in group). For the input of the lower station to be freed up again, the model is waiting for the first item to finish processing on that station, which it never will as it was brought to the other station.

Due to the randomized process times, this could probably still happen if you switch the connections around. To prevent this you could just not use any connections between the processors, as all logic is controlled by the process flow anyway. Just push the item to the respective list in "Send To Port" instead of "Use Transport".

wrongstationinput.png (42.3 KiB)

sendtoportpush.png (86.9 KiB)

Answer 2 · 2021-06-09T14:27:41Z

Philip Diem answered Jun 9, '21

Thanks to both of you, I see where the problem is now!
As I didn't use distibutions for the processtimes the problem didn't occur in the small test model.
It should also work to just request the flash station thats equal to the designated sendto port on the assembly station.
Thanks again :)

Greetings to Spain and Germany

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