topic Re: Simple concept proving difficult for newbie to implement - Cranes and lists in FlexSim Forum

Simple concept proving difficult for newbie to implement - Cranes and lists

stephen_m2 — Wed, 23 Jun 2021 18:03:14 GMT

[ FlexSim 20.2.3 ]

The attached model put 3 boxes into 3 queues. The process logic loads the list upon entry to the queues all at time 0. Then a token is created at time =20 and wants to pick up the box at queue2 and deliver it to the processor1. This should be easy but I can't get it done. Please help me to learn flexsim better.

Thank you

listTestClosest.fsm

Re: Simple concept proving difficult for newbie to implement - Cranes and lists

eric_m3 — Wed, 23 Jun 2021 20:38:28 GMT

Hi @Stephen M2, you just about had it right in your model. The main thing you were missing was a reference to the items themselves in the list. Because of this, the process flow didn't know what items it was supposed to tell the crane to move. There were a couple things I did to fix this issue. First, on the Wait for Event sources I added a piece that records the item that entered the queue (which caused the token to be created in the first place). You can see how I did that in the image below. I assign a label to the token called "Item" that stores a reference to the item that entered the queue.

Next, on the Push to List activity I changed the Push Value to token.Item. This will push the item to the list instead of the token. Now when the Pull from List activity happens, it will pull a reference to the item in the model that we want to move. One other thing I changed was the Query in the Pull from List activity. I changed it to be WHERE Product = Puller.Product. This will pull items from the list that match the Product value of the Puller. In this case, the token is set to be the Puller so it's really matching the token.Product label if that makes sense.

As a bonus, I also added a second process flow to give you an example of how some of your activities could be consolidated if you wanted (by no means necessary, just if you were curious). To see how this works, just connect the sources to the activities below them and remember to disconnect the sources in the original process flow.

Let me know if you have any questions about this!

listtestclosest-em.fsm

Re: Simple concept proving difficult for newbie to implement - Cranes and lists

stephen_m2 — Thu, 24 Jun 2021 00:00:17 GMT

@Eric M Thanks so much. I have 40 years of modeling experience mostly with arena but very little with these modern object oriented language/tools. I knew it was because the flowitem wasn't tied to the process flow tokens but just didn't know how to do it. I do like flexsim but still much for me to learn

Steve

Re: Simple concept proving difficult for newbie to implement - Cranes and lists

eric_m3 — Thu, 24 Jun 2021 14:09:40 GMT

That's great! Thanks for reaching out, we're always happy to help as you keep learning the software.