question

Edwin Purwanto avatar image
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Edwin Purwanto asked Edwin Purwanto answered

Can we count number of flowitem in a power and free conveyor?

Hello,

Power and free conveyor is usually utilized as a buffer to keep flowitem if downstream is full.

In this case, should we need to access how many flowitem already in the loop and then redirect flow if its full, is there any efficient way to do so? One way is by using counter label, but I was thinking of counting dog position, whether it was occupied or not.

Best regards,

edwin

FlexSim 16.1.0
power and free conveyor
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Sam Stubbs avatar image
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Sam Stubbs answered

There's a way to restrict access to parts of the conveyor based on content number (or other variables) using some of the trigger options in the Decision Points. I've created an example which I'll attach below.

Essentially I've created a power and free conveyor with in a loop with entry and exit points. The conveyor will restrict how many items can exist in the loop (in the example I set it to 10) and it will also restrict how many items can be in the exit area at a time.

The way I accomplished this was by adding a Decision Point (DP) at the start of the loop, and under the On Arrival trigger in the drop down I selected Area Restriction > Enter Area. The owner object (start of the area) being itself (current) and the max content set to 10.

Then I had a DP at the junction where items either leave the conveyor or loop around again. Here I simply added a Send Item function on the On Arrival trigger that checks if the content of the exit area is less than 3, send the item to that area, otherwise continue on the loop. Finally as the item enters the exit area, there's a DP with a center port connection to loop area, that designates the item leaving the Loop. You can see the example below and pick it apart for whatever you need. conveyorexample.fsm


conveyorexample.fsm (22.1 KiB)
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Edwin Purwanto avatar image
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Edwin Purwanto answered

Hello,

So I check the source code of enter area and exit area and found a label "dp_RestrictedContentArea" is largely responsible for increasing max item and decreasing it upon leaving.

What I observe is in my model, upon a flowitem reaching DP4, it is supposedly activate exit area and decrease "dp_RestrictedContentArea" label. Here, it was not happening.

In normal example, this one works, but here it doesnt work. I am wondering of some difference:

1. In normal example, you use centerobject as an area owner, here I use inobject. Is this make any difference?

2. I change slightly the enter area script into conveyorsenditem, instead of conveyorstopitem in the enter area script.

Thank you very much for your kind help and attention

Best regards,

Edwin

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Edwin Purwanto avatar image
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Edwin Purwanto answered

Hello Sam,

Thank you very much for your help.

On my model, I have 3 area, red one only allow 4, green only 10, and the buffer blue one allow 30.

The blue one supposedly only to hold goods when either red or green start to free (thus exit area DP on the bottom part of conveyor.

What I encounter is that flowitem that is entering blue loop unable to break free regardles red or green already free.

Thats why, I am asking of what command it is to invoke the content of an area (red for example). My presumption is that the flowitem exiting red is not really exiting it.

Thank you for taking time to look for my question

Best regards,

Edwin

test8-2.fsm


enterexitarea.png (111.6 KiB)
test8-2.fsm (171.4 KiB)
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