Need Circuit network counting help

[ili]

Hi
I want to load an Electric furnace with Iron to make Steel when I send it a Steel signal
Then I need it to stop when the Steel signal is stopped AND the furnace is empty of Iron (so it can do other smelting)
I tried to do this by counting the input and stopping when it have 5 plates but my setups I came with does not work

The right setup works but only if I insert the fifth iron plate to the box by itself (so no stacking), If the last plates are stacked the counting get wrong

The left setup don't have this problem but is not working because on the fifth iron plate the counting goes from 5 to -5 instead of going to 0 and I don't know why (5-5=-5?)

So how can I do this
Thank you!

[ili]

Update
I think I fixed the right one by adding this 3 to overcome the staking problem
But it have 4 combinations now which take too much space, is there a better way?

[Acarin]

You have run into the Tar Baby of Factorio - trying to build a smart, workable steel furnace

The best solution so far is XKnight's (viewtopic.php?f=193&t=31766), but the general conclusion appears to be that, in the current version of the game, it is functionally impossible to make a lock-free smart furnace that includes steel.

However, if it is ONLY the steel you require, but you want it to be counted for precise control, that should be possible. But beyond me Because of the variations in stack sizes, tied to the "input buffer" size of the furnaces, it is an awkward problem. Best suggestion that I have is to look at this thread (viewtopic.php?f=193&t=25615&start=40), scroll right to the end and test out khoul's post regarding forcing inserters to only pick up one item.

[ili]

You have run into the Tar Baby of Factorio - trying to build a smart, workable steel furnace

The best solution so far is XKnight's (viewtopic.php?f=193&t=31766), but the general conclusion appears to be that, in the current version of the game, it is functionally impossible to make a lock-free smart furnace that includes steel.

However, if it is ONLY the steel you require, but you want it to be counted for precise control, that should be possible. But beyond me Because of the variations in stack sizes, tied to the "input buffer" size of the furnaces, it is an awkward problem. Best suggestion that I have is to look at this thread (viewtopic.php?f=193&t=25615&start=40), scroll right to the end and test out khoul's post regarding forcing inserters to only pick up one item.

Thank you
Very helpful

I managed to build the Smart furnace setup with the 4 combinators method from my previous post that can process:
2 full Iron belts OR 2 full Copper belts OR 1 full Steel belt (or a combination of them)
But as you can see its peaked with combinators

2016-10-11_17-11-12.png (2.13 MiB) Viewed 1688 times

2016-10-11_17-12-33.png (1.67 MiB) Viewed 1688 times

But with the stack limiter method I think I can do it by using 3 combinators like this:

2016-10-11_16-42-50.png (475.16 KiB) Viewed 1688 times

But the idea of setting a unique signal for every furnace and then counting them with a single combinator is interesting, probably can get it down to 2 combinators per furnace (convert from and to the unique signal)
Update: it can actually be done with ONE combinator + Controller
Reading (red line) include combinator to convert plates inserted to unique signal for every furnace
Controler include counter with stack compensator + red to green bridge + steel threshold that send all available signals from Constant Combinator to the activation line (Green)

2016-10-11_20-05-40.png (786.78 KiB) Viewed 1677 times

I still like to know if it can be done better
And also to know why is my original post left setup jump to -5 instead of 0?