Pull Logic Dillema

[William Proctor]

I have a turntable that is pulling palletized loads from either a palletizer outfeed conveyor or a main conveyor line that is conveying pallets from other palletizers. I'm using the Pull command to determine which input port to use based upon a series of user-defined conditions.

My problem is that if none of the conditions on the Pull rule are met then I have to select a default port to use. Once this happens, then the model will no longer look at the conditions for pulling. I have looked as sending messages and opening and closing the ports to initiate the Pull logic (which didn't work) and finally noticed in the user-manual that the Pull logic will only execute once and ignores the opening and closing of ports.

Any suggestions out there on how I can solve this dillema in a simple way?:(

[William Proctor]

It's OK now. I figured out a work-around. I default the port to zero (0) which essentially leaves all ports open. Then I close the output port to the conveyors coming into the turntable until they are ready to send pallets to the turnable. The Pull rule is unable to pull flowitems if the output port is closed, so "wah-lah".:D

[Brenton King]

Bill,
I was working on this model for you but it looks like you figured it out. Maybe you could still find something useful in it though. I wanted to set up a situation in which the pull requirement would constantly be changing. So in this model I have a queue that is constantly filling up with 10 different item types. I have a table that keeps track of how many of each of the 10 items types are in the queue. The items will stay inside of the queue until you hit execute in the open script window in the bottom corner. When hit, the script window sends a message to the processor the runs some code to decide which item to pull from the queue. I have it pull the item type that is the most common in the queue. If there is a tie it pulls the first one it comes to. So, the reason this is cool, is because the numbers in the table are constantly switching but the pull requirement isn't fired until you hit Execute which sends a message to the queue to open it's output port and pull the item type shown in Processor's properties window under the ChosenItemtype Label. I hope this helps even though you already solved your issue.
Brenton
Flexsim Support