I want this - also to meassure other things. See
https://forums.factorio.com/forum/vie ... t=10#p6118
Because:
I want to build something like a "blood-cycle" which contains the right amount of all items to be built and is not too "thick" to move. In this case: A belt, which goes in a circle and each factory takes, what's needed. So I want to meassure, if the density of all items are right and if - for example - iron plates are too high it stops inserting iron plates into the cycle.
Sounds simple.
But I made several tries to build that with smart chests, filter inserters, smart inserters etc. but there is always the problem, that I cannot measure the right density. (I really tried many tricks, some worked more or less nice.) But in all situations I came to a point, where nothing moves anymore and doesn't repair itself. The satisfying moments where, when the factory runs for some while. The idea is really fascinating because it makes enables a completely new approach in building. For example: I tried to make blue potion with that and all factories take and inserted into one belt and it worked - for some while. So I think the idea is not bad, but needs some more tuning.
Really thought a lot about it and what is needed to do that. This was my result:
- sensors, which measures the density (or other things) on a belt.
- controller that turns on/off the inserters into this cycle
- wiring in-between
I see many questions-marks.
Think to a heating: There are 2 thermometers as input (e. g. outside temp and water temp), to a controller. The controller makes some simple calculations, and calculates how much time the burner is opened to heat (the burner can only turned on or off). As the result, the living rooms are always well temperated.
The same regulators are needed, to control the densitiy of item-flow and have the right mixture to . In this case: measuring the total density of items (translated into heating, this is the "outside-temp"). Then measuring the densitiy of iron-plates (="inside-temp").
Both values are the input of the controller. If densitiy is too high, nothing is inserted. (if outside temp > 20 °C no heating at all!). Logically, if iron-plate density is very low and overall density is also low, the inserters should insert as fast as they can. But whats's inbetween, when you cannot say exactly how much stuff should be insertert into the cycle?
Now it gets a little bit complicated. Please look here:
http://en.wikipedia.org/wiki/Controller ... _theory%29
I think this is a little bit better (in german, but the pics explain much more here):
http://de.wikipedia.org/wiki/Heizungsregler
This means: If the difference between total items and iron-plate-density is only a little bit too low, I need the inserters to work just for some seconds or less. I don't need them to work until the optimum is reached, because this would be too much.
This can only be obtained with such a controller-device - there is no other way to keep the levels of items ideally balanced!