"hold-scanning" drop subtraction

[Sneaker2]

This is a rather special question to a special goal and problem.

My goal is to set up a belt system, that works like the logistic drone system, but as said with belts only. This involves dividing the belts into blocks and a lot of counting of each and every item. The scanning function of belts, inserters and combinators helps a lot here , but while testing this I have run into a dead end.

upon entry of an item, the system registers this item pretty fast, because the trigger point is at the beginning of the square or upon grabbing of the inserter. the item is added to a counter and also added to the entire system. the problem occurs at the end of the system, when an inserter grabs the item and puts it into chest.
the inserter will give a pulse to the system, when it grabs the item, so that the system knows, that this item is no longer on the belt.
but this puls-signal comes way too early for the system, because it takes some few milli-seconds until the item reaches the chest, where it will be added to the system count again. This gab between the inserter-grab and the chest drop is a blind spot in the system, which constantly falsifies the system count, because the item left the belt but isnt in the chest yet either. The consequence is that the system thinks that the item simply isnt there anymore and starts to send a further item in order to correct the demanded count of the chest.

I need a system, that registers item upon leaving the inserter or belt-scanner, in order to make my system work and get rid off those blind spots in the system. The good thing is that they only occur at the end of the system, when an inserter drops items in a chest/box. I dont have those problems in the midddle or at the beginnning of the system. I wonder if someone could help me to set this up with arithmetic and comparing combinators, which would work for any item. I know how to make counters, but I have too little knowledge about the ways the combinators work in order to set this up the other part.
The thing I also dont know about inserters is, if they drop a stack of items 1 by 1 into a chest or as a full stack.

If I could send an item-puls to the counting-system upon leaving the inserter, this would help me a lot and integrate it into the system very fast.

sorry for the special question, but maybe someone knows what I am up to and can make a guess.

[Frightning]

Isn't it possible to get an inserter to report to the circuit network what it's holding in 0.13?

[Sneaker2]

Isn't it possible to get an inserter to report to the circuit network what it's holding in 0.13?

It does, and i am using that, yet the timing of the scan is the problem. Normally I would take puls scanning at the inserters. since puls scanning scanns items to early at the end, this isnt an option. So I would have to select the "hold scanning", yet I have no idea how to convert this into a puls signal, when the items leave the inserter.

I would need some kind of memory cell, that saves the highest scanned item-count on the inserter and that sends a puls to a counter each time this count gets reduced. the problem is also, that I dont know if the item-number that the inserter is holding is reduced 1 by 1 into a chest or if the stack gets dropped all at once. this is important to know, because I need to know if the counter gets reduced by -1 impulses multiple times or by just one number in order to create the right set up to do this.