Reversing Conveyor Decision Point Error

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question

Leo L6 asked Sep 11, '23 Felix Möhlmann edited Sep 12, '23

Reversing Conveyor Decision Point Error

Hello,

I'm trying to use an event trigger from a decision point to reverse a conveyor and move it to a sink. However, the decision point is not able to accurately keep track of the current content on it. It's seems like when the conveyor reverses the decision point is not able to track the fact the the flow item has left the decision point even though it has already left. On a related note, the event triggered source that is triggered from the decision always creates two tokens, presumably because the decision point is triggered once in one direction and a second time in the other direction. How can I make sure the decision point is accurately keeping track of the current content? And, how can I make sure the event trigger source isn't creating 2 tokens every time it's triggered?

Attached the model

reverseconveyorbug.fsm

Software Version:

FlexSim 22.0.16

conveyors decision point event trigger

reverseconveyorbug.fsm (47.8 KiB)

Answer 1 · 2023-09-12T07:08:10Z

Paula LG answered Sep 12, '23

Hi Leo,

I have modified your model so that it does what you wanted. To do so, I combined what @Felix Möhlmann has previously commented on how obtain the correct statistics on the Decision Point and a decide block added to your own logic so that the second time the "OnArrival" event is triggered, the token is sent directly to a sink, by reading a label on the Decision Point that is changed when the conveyor is reversed.

I attach your model with those changes here: reverseconveyorbug.fsm

I hope it helps!

reverseconveyorbug.fsm (50.4 KiB)

Answer 2 · 2023-09-12T06:53:48Z

Felix Möhlmann answered Sep 12, '23 Felix Möhlmann edited Sep 12, '23

The only reliable way I know of to not trigger the decision after the item is reversed is to have it trigger by the leading edge of the item instead of the center.

If you then also wait a finite amount of time (like 1/1000th of a second or you choose the time so that the item still reverses when its center passes the DP) before stopping the item, the output statistic of the decision point will update correctly.

reverseconveyorbug-fm.fsm

reverseconveyorbug-fm.fsm (48.7 KiB)

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