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Craig DIckson avatar image
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Craig DIckson asked Joerg Vogel commented

Elevator - won't carry two and stuck on "nearest"?

I am using process flow to create items (boxes) in a stack of queues at different elevations at random times. The queues are all connected to a conveyor input transfer, using an elevator as transport. I have three things happening that I don't understand:

  1. I set the elevator for capacity of 2, but it will only ever carry 1 box, even if there are two in the queue it's accessing.
  2. I want it to pick up the boxes FIFO, but it seems to want to do "nearest", so (since the conveyor is at floor level) it works from the bottom up.
  3. Occasionally a box gets stuck in one of the queues (and not always the same queue). (see screen cap below) When this happened I double checked the connections to the conveyor (A) and lift (S) ... and they were definitely there.

The third item feels like a bug, and I'm really not sure on the other two -- I tried a number of settings and didn't get much change at all. What am I doing wrong?

FlexSim 18.2.0
process flowelevator
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1 Answer

Steven Hamoen avatar image
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Steven Hamoen answered Joerg Vogel commented

@Craig DIckson It would help if you would post the model but I think I can answer the first 2:

1 If the receiving party can only receive 1 box the elevator will only take 1 what ever the capacity is. So a way to solve this is to put an invisible or very small queue in front the conveyor and connect your queues with that queue. Or also control the elevator with process flow completely

2 In this situation the conveyor opens the input port again and starts looking through the input channels for new products. And this is always the same order. You could fix it with the pull on the entry trigger (pull longest waiting) but I think there is a bug there and it doesn't work very well. So again here a queue in front of the conveyor would do the trick and you can use that pull trigger. Or use a list here also. Or handle it completely in process flow again.

3 could be a bug but for that we really need the model

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Joerg Vogel avatar image Joerg Vogel commented ·

at 1: set in the Entry transfer the number in transit higher.

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