question

A good option to sync different processes (in this case the full pallets being delivered to and later removed from the floor storages and the operator collecting the boxes) is to use lists. If have don't experience this lists yet, I recommend to first read through the linked documentation page. It will make understanding the changes in the model much easier.

In this model, a special function of the list is very useful the "Use first SELECT Value as Quantifier" option.

Before the pallets are pushed to the list, the label "numBoxes" is added to them and a respective field is also present on the list.

Now, when querying the list, we can use the SELECT clause. The quantity field in the Pull from List activity now does not state how many values should be pulled from the list but how much of the "numBoxes" value will be pulled. For example, the full pallet has 12 boxes on it. After one token moves through the Pull from List activity, the numBoxes value is reduced by 1 to 11, but the value itself, the pallet stays on the list. Only when the label value reaches 0 will the value be removed from the list. This is useful, because the pallet can be 'found' on the list as long as there are boxes on it. And when the labels becomes 0, the token that pushed the pallet to the list can now continue. So it's an easy way to keep the pallet in the queue until it is empty.

You might want to have a view of the list open while running the model to better follow what is happening.

test-wpo3-fm2.fsm

Any newly added activities in the attached model are marked in green.