The logistic network provides the circuit network all of the items (and their counts) that are in the logistic network, however, that is not the only way to get all of the items in some area into a circuit network. In my case, I am trying to make a sushi belt that can have 20+ items on it.
Getting a count of how many items are in the sushi belt is pretty straight forward, there are lots of examples of that.
What I am wanting is a way for an inserter that is taking things out of an assembly machine to know if the sushi belt has too many of that item. In your example, you have the inserter manually configured to not insert an item if the circuit network says there is over 100 red belts. I want a way to do that without having to manually specify what the item type is, and instead of the inserter look up what it is holding.
So in your example, the inserter would pick up a red belt, look to see if there are less than 100 red belts in the logistics network before adding it to the chest. However, the next time the inserter might pick up something, it might pick up a blue belt, and then it would look up to see if there are less than 100 blue belts in the logistics network before adding it to the chest.