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Kari Payton avatar image
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Kari Payton asked Adrian Haws edited

Items disappearing when pushing and pulling from list.

First I pull a machine from a list, but when I try to push back to the list the item does not go back onto the list. I start out with 4 machines. Pull one, so now I only have 3 items on the list. Then I push the machine back to the list and the number of items stays at 3. @Adrian Haws

Pull

Push

list2.png

FlexSim 16.1.0
push and pull list
list1.png (42.8 KiB)
list2.png (39.5 KiB)
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Adrian Haws avatar image Adrian Haws commented ·

@Kari Payton What it is that you're trying to accomplish by pushing and pulling the machines? Would it be possible to see your model?

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Kari Payton avatar image Kari Payton Adrian Haws commented ·

@Adrian Haws I can't post it. I created machines and pushed them to a list, like you showed me yesterday. So in my custom process flow I pull that machine, the operator travels to the queue and picks up the 3D object, delays, then returns the object back to the queue. I then try to push the machine back to the list but it disappears.

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Mischa Spelt avatar image Mischa Spelt commented ·

Hi @Kari Payton. It's hard to determine without seeing the model, but is it possible that you have a Sink somewhere in the flow that pushes the item onto the list? Because if you pull it from the list elsewhere and the original token falls into a sink, the puller suddenly holds an invalid reference which can sometimes lead to unexpected effects.

E.g. in a flow like below, where the Push To List pushes the token itself, you will see that the "pulled" label has become "NULL" by the time the token on the right hand side reaches the Run Sub Flow activity.

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Kari Payton avatar image Kari Payton commented ·

@Adrian Haws I edited the model you sent yesterday to demonstrate. @Mischa Spelt1639-global-list-example.fsm

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Adrian Haws avatar image Adrian Haws Kari Payton commented ·
@Kari Payton

The way I previously understood it is that you were pushing and pulling a 3D object (the box) to and from a list in separate Process Flows. With your example now are you pushing the object or the queue? When you said machine that sounded to me like something such as a processor.

Without still fully understanding what's going on in your model a couple things you might look at is the labels you're using with the "Push to List" and "Pull from List" activities, as well as the type of list.

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Kari Payton avatar image Kari Payton Adrian Haws commented ·

@Adrian HawsI have 4 objects that I'm calling "machines" that are being created in queue2. Then I pull one of those objects from the list, pick up the object, and want to put the object back on queue2. But when I run the model, as it shows, the list never recognizes that the object was pushed back to the list. Instead of showing 4 entries it only shows 3 entries. I have tried both fixed resource and item lists to no avail.

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1 Answer

Adrian Haws avatar image
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Adrian Haws answered Adrian Haws edited

@Kari Payton The reason the object wasn't being pushed back onto the list is because it had the wrong reference. In the "Push to List" within the FixedResource flow you had been pushing "Token: Entering". Rather, you should push "Label: Item" since that's what you assigned the object to when you originally pulled it from the list. Also, make sure to check the box called "Keep On List On Early Release" in the "Push to List" activity.

See updated model.


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