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  #1  
Old 03-06-2009
mariogib mariogib is offline
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Default problem with rack object

Hi to everyone,

I'm learning how to use Flexsim and I have some
questions about the tools:
The Rack Object take out the flowitems using
the FIFO criterion ((First In First Out),
insted I need to take out
them as per a label. Here what I do: I assign to every flowitems a
specific label with some informations. In the OnEntry Trigger of the
Rack I set this label
using "Setlabelnum (item,”RN”,duniform(1,1000)".
Now: I want the Rack Object takes out the
flowitems under an
increasing order of RN, how can I do?

I tried to insert
"SortByLabelnum, Sort Order ascending, Label Name RN" in the OnExit
Trigger of the Rack, but it didn't work.

Do you have some suggestions?
Enclosed with the model for better understanding of my problem.

Thank you!
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  #2  
Old 03-06-2009
Brandon Peterson's Avatar
Brandon Peterson Brandon Peterson is offline
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Mario,

In a queue you can get away with sorting the queue so that the item ranked first is the one you want to leave first. You can try this in the rack and you were really close to doing it right but you were using the wrong trigger. The exit trigger fires when an item leaves the rack so any sorting of the item done at that time is of no real meaning because it will leave regardless. You want to do the sorting on the entry trigger. This way the item is placed in the right sequence before it leaves.

Another way to do this is to have the down stream object "pull" the items from the rack. To do this go to the flow tab of the down stream object and check the pull check box and then specify in the pull requirement that you want to pull the object with the highest label value. There is a pick list option to pull an item with a specific label and you would have to modify this to be the item with the highest label value.

Good Luck,
Brandon
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Old 03-06-2009
mariogib mariogib is offline
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Default

The problem is that I don't manage to put the label values in order (ascending or descending), even in the first and in the second method
i prefer the 2nd method, so how can I do this?

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Old 03-06-2009
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Brandon Peterson Brandon Peterson is offline
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Mario,

First, you didn't have a label called RN on the flowitem and you can't set or read a label that doesn't exist. Labels can be added in the code but are best added in the flowitem bin.

Second, You were using a transport to remove the items to a queue that had a content > 1. The problem with this is that the items are being released and a task sequence created as soon as there is space available in the queue. Space available is determined by the number of items in the queue and the number of items that have been released to the queue. So, if the queue had a max content of 10 then you would see flowitems leave in the order in which they arrived until there where 10 items in the queue or waiting to go to the queue. Items are released this way so that if there are multiple transports they can all be used. The solution in your case was to set the max content of the queue to 1. If you needed the content to be greater than 1 then you could place another queue after the first with a max content of n - 1, with n being the content desired.

I modified your model to include the label on the flowitem, set the content of the queue to 1, and redid the code so that it was all on the entry trigger. I also added some code to the entry trigger of the rack to set the color according to the RN value. The higher the value the closer to white and the lower the closer to black.

The model now works correctly with the whitest item being removed first.

Good Luck,
Brandon
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Old 03-07-2009
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Default with perishable products ???

Brandon thanks really for your disponibility,
tHe flowitems, that I consider in my model, are perishable products that go into the rack with a residual life and they come out with minor residual life ( reduced by the time of permanence into the rack = on exit time - on entry time).
For that reasons I can't use the method that you explained me because I can’t consider the on exit time in OnEntry Trigger.
How can I do?
I enclose you the new model.
thanks
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File Type: zip model1.zip (46.3 KB, 203 views)
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