question

I made a demo model, that show some of the techniques you might use in building a Kanban model:

KanbanDemo.fsm

It isn't the situation you show in your question, but it has some similar concepts. So I'll describe this model a little bit.

First, there is a Processor. That processor consumes items from a tote, until that tote runs out of items. Then the Processor tries to begin using items from the next tote. If there is no next tote, the Processor would be blocked.

Every time the Processor empties a tote, an Operator puts the tote on a shelf of empty totes, and then tries to get a full tote from another shelf. Once a full tote is available, the Operator takes it to the Processor.

Once three empty totes accumulate, another Operator takes the totes to some machines (a Combine and Separator). These machines just represent the time it takes to refill the empty totes. Once the totes are refilled, an Operator puts the full totes on the full shelf.

There are many techniques used in this model, but probably the one to focus on is the List in Process Flow. A List is ideal in Kanban, because a List synchronizes requests with the resources for that request. You use a List through two activities: a Push To List, which makes something available, and a Pull From List, which makes requests on the List.

Here's one example in the demo model: the activity called "Get Empty Totes". That activity is a Pull From List. The token waits at that activity until a complete batch of empty totes is available. Then, it creates the task to take all the totes to the Combiner/Separator. If you click on the "Get Empty Totes" activity, you can see that a blue line is drawn to the Empty Totes List. If you click on the Empty Totes list, you can see that empty totes are added to the list when the Operator puts it on the shelf.