question

Patrick Zweekhorst avatar image
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Patrick Zweekhorst asked Jeff Nordgren commented

Pull strategy does not seem to work on conveyor entry transfer

Hi All,

I have a problem with the pull strategy on the entry transfer of a conveyor. The small example situation (see attachment) is that 1 operator brings boxes from 2 conveyors to a single conveyor. The boxes from the two conveyors should be transported in order of creation. I have therefore selected the pull strategy longest waiting on the entry transfer. This however does not work. When you take a look at the code that is behind the longest waiting option you can see some issues. The first problem is that current points to Conveyor System, and not to the conveyor. This can be solved by setting current equal to param(1), but that does not completely solve the problem. tempobject is the exittransfer on the conveyor, and the exit transfer of course has no content.

Is it possible to fix this option from the dropdown menu?

Thanks in advance,

Patrick

entrytransferpullbug.fsm

FlexSim 18.0.1
conveyorpull strategy
entrytransferpullbug.fsm (36.2 KiB)
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1 Answer

Jeff Nordgren avatar image
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Jeff Nordgren answered Jeff Nordgren commented

@Patrick Zweekhorst

Because of the uniqueness of design and how the conveyors work, the Pull option from a Conveyor EntryTransfer to any Conveyor ExitTransfer will not work, as you have already discovered. So trying to just change the dropdown menu will not work.

The way I get around this "problem" is to have a short conveyor section at the end of each conveyor that is not attached to the conveyor (I deleted the inline conveyor connection). Then I have a Queue that is given a "plane" graphic and colored so that it is concealed underneath that short conveyor section. The main Conveyor sends flowitems to that Queue. Then the Queue is connected to the single Conveyor. For all appearances, it appears that the operator is pulling items from the 2 inbound conveyors when in reality, it is pulling them from the concealed queue. This is the best work around that I know of to pull from conveyors.

Take a look at the changes that I have made to your model and see if this solution will work for your situation. If you have any problems or questions, please let us know.

Thanks.

entrytransferpullbug-jn1.fsm


conveyorpull.gif (4.2 MiB)
entrytransferpullbug-jn1.fsm (37.6 KiB)
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Patrick Zweekhorst avatar image Patrick Zweekhorst commented ·

Hi @Jeff Nordgren ,

Thank you for your explanation and the example model. It is a clever way to get around the problem I had. I will try your solution in my model and come back to you if I have any other problems.

Patrick

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Jeff Nordgren avatar image Jeff Nordgren Patrick Zweekhorst commented ·
@Patrick Zweekhorst

Great. I hope it works out for you. If not, please let us know.

Thanks.

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