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Aaditya J avatar image
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Aaditya J asked tannerp edited

What are the Pros and Cons of Photo Eye and Decision Points

I am designing a Conveyor layout, with different hold times and area restrictions. I am confused with Photo Eye and Decision Points. Can you please elaborate why we have Photo Eye and Decision points.

FlexSim 19.0.0
decision pointsphoto eyeconveyor system
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Joerg Vogel avatar image Joerg Vogel commented ·

A photo eye is a visible object, that behaves similar to the real object. Sometimes you need a location that sets or gets data to or from items that you need only in a simulation model, then you use a decision point.

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Aaditya J avatar image Aaditya J Joerg Vogel commented ·

Thanks for the reply. I am looking for mostly the triggers portion of it. In case of Photo Eye We have "On Cover, On Block, etc" on Decision Point we have "On Arrival, On Continue, etc" what is the purpose of this triggers, which conditions we can achieve with that?

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David Seo avatar image David Seo Aaditya J commented ·
@Aaditya J

DP can't get the status of the flowitems's blocked, Covered time, etc. It can only check to arrive and to continue.

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Aaditya J avatar image Aaditya J commented ·

photoeye-vs-decisionpoint.fsm

I have Uploaded a model, please find below the problem statement.

- I need to hold the part between PE1 and PE2 for 15 min, including its travel time from PE1 to PE2. I have updated the labels to track the times. I am doing same with DP, you can observe the times they are waiting in the zone are different. Please guide, can we use Photo-Eye the same way as DP to govern the hold logic.

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tannerp avatar image tannerp Aaditya J commented ·

@Aaditya J, The discrepancy in your model comes because your PE1 assigns the "time" label immediately and the DP1 assigns the "time" label On Continue (after 10 seconds). You should use the same trigger events in both cases to achieve the same timing. It's just an issue of the FlexSim order of events.

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Aaditya J avatar image Aaditya J tannerp commented ·

Yes, I know that. Do we have any such state in Photo Eye like continue in Decision Point. As I do not want to use two different object. If not then I will shift all my Photo Eyes to Decision Points. Please suggest.

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1 Answer

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tannerp avatar image
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tannerp answered tannerp edited

What you see in the triggers pick-list is what is available, so the photo eye doesn't have an On Continue trigger built in. That said, you could use custom code to open/close the ports in Process Flow with event triggers, although that might be more trouble than it's worth.

I would recommend using whichever object's behavior you think accurately represents your process in real life. It sounds like you want the items to stay for an extended period of time (15 minutes) at the second photo eye/decision point. If that's the case, use the decision point because it seems to be modeling your desired model behavior correctly.

There's not really a universal right and wrong choice. Like @Jörg Vogel stated before, a decision point is a modeling tool, not a real life object. Maybe this can help you decide.

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Aaditya J avatar image Aaditya J commented ·

Thanks for the reply, I think this will help.

Some how I am not getting the option to accept the answer.

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tannerp avatar image tannerp Aaditya J commented ·

I'll take care of it. These were posted as comments instead of replies. It should be good to go now. Thank you!

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