Request items for insertion: Signal propagation difficulty

[Bl0bs]

Hi.

I have been struggling with this issue for quite some hours and still haven't found a solution.
1. I would like to request items for a requester chest through a constant combinator.
2. The requested items are to be inserted to belts/machines/trains and thus I have to keep track of what is inserted.
3. Once the requested items are inserted I will manually disable the constant signal.
4. The insertion tracker is to be "reset" once the constant request signal is gone.

My setup so far is based on a memory cell counting inserted items as shown below:

setup_1.PNG (996.7 KiB) Viewed 825 times

In short: the decider combinator is supposed to "reset" the signal by making sure the sum of the input is always 0.

I am not entirely sure but I believe the system is faulty due to signal propagation:
Once the decider combinator activates it takes some ticks before the memory cell is updated and the signal returns to the combinator for evaluation. In this time it has sent multiple signals to the memory cell for addition and thus the counter is incorrect. I have tried changing the system to quite a few varieties however I have not yet succeeded in getting something functional.

I hope some of you are able to help me out.

Best regards
Bl0bs

[Hedning1390]

Any operation takes one tick, so if you multiply the signal with -1 and add the result you will get exactly one tick of the signal before it cancels out every time it changes state (then you just have to figure out how to not count when it goes back to 0).