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farh123 avatar image
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farh123 asked Felix Möhlmann commented

How do I control flow of two types of items in a restricted area?

I have two types of items (type 1 and 2) that both uses the area where S7 is located (shown in the image) where they then travel to their respective destinations (D).

Type 1 items travels to both D1 and D2 using the round robin method (every other type 1 item goes to D2). Type 2 items travel to D3.

The issue I'm having is that both Type 1 and 2 requires S7 to travel to D2 ad D3, respectively. I need Type 2 to only flow to S7 when Type 1 doesn't block C1 (decision point) and vice versa. It should basically follow the FIFO method.

I used the acquire area access and release area access method (under Trigger) inside the 3d model space to make this work but both item types get stuck on their respective decision point. Now I'm using the process flow method to get this to work but again they both get stuck (as shown in the image).

I have attached my file, please have a look at my process flow. Let me know if there are better alternatives compared to my approach.


CTA_1.fsm1668637482279.png

FlexSim 23.0.0 beta
process flowitemroutingarea access
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cta-1.fsm (153.4 KiB)
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1 Answer

Felix Möhlmann avatar image
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Felix Möhlmann answered Felix Möhlmann commented

You still have the "Aquire Restricted Area" triggers set which interfere with your process flow logic. Also, the label used in the custom code "B" should be 'tray2' instead of 'tray'.

cta-pf.fsm

Your process flow currently enforces that the two types have to alternate. To use FIFO instead, you can simply remove the query in the Pull From List activities.


I don't know why the restricted area method didn't work for you. Was the release set on the station in the middle of the junction? Because items that move to D3 would not trigger it due to their trailing edge not passing the center of the station.

In the attached model I use two more decision points to release the area.

cta-restrictedarea.fsm


cta-pf.fsm (128.9 KiB)
cta-restrictedarea.fsm (129.2 KiB)
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farh123 avatar image farh123 commented ·
Thank you! I kind of figured last night that the list activity were causing problems to my simulation. I removed it and now it functions the way that I wanted it to. Also, I just noticed the reason why I wasn't able to get the restricted area method to work was because I used only A connections instead of not including S connections as well.
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Felix Möhlmann avatar image Felix Möhlmann farh123 commented ·
A-connections can work too. You just have to make sure that all acquire/release triggers refer to the same 'owner object' of the area.
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