Factorio Forums

What I'm trying to accomplish with circuit network:
An Iron chest has < 50 plates (and it needs 25 more)
I want the inserter at the source chest (that feeds the belt) to unload exactly 25 plates and put them on the belt headed towards the Iron Chest.

I can't figure out how to get the inserter at the source chest (that feeds the belt) to unload exactly 25 plates (count up to 25) and then stop.
I don't want to wire up the entire belt just to count things on it. There has to be a less tedious and more efficient way...

EDIT: nevermind figured it out (see attached)

explainer for other people since I've never really seen this laid out on youtube or...anywhere.
1. You have the iron chest inserter pulse held items up to a decider (looped back on itself, takes its own output as input and therefore "remembers" it)
2. You have the inserter feeding the belt pulse held items up to a math combinator (held item count * -1) and then wire that over to the decider from step 1
3. When inserter 1 takes something, the storage inserter (#2) receivers the taken item as a filter from decider 1, grabs the items from storage box, and the count of what it grabs are subtracted from the number remembered on decider 1 (which is our current outstanding count of items needed from storage).

Copy blueprint

The red wire counts the items on the belt. The green wire counts the items in the chest. The inserter at the source chest reads both wires, and if iron plates is less than 50 it adds more.

Really, just reading the entire belt is more precise and scales easier to have multiple assemblers setup on the same belt loop: 1 station to feed items onto the belt until the full count of items actually on the belt meets or exceeds live demand (constant output from consumer chests), 1 station to pull excess items from the belt.

Just a little tip I noticed: if you put down a ghost (from blueprint) with belts that are wired to read contents (in the blueprint) - when the actual items are placed on the ghost, you actually get the green/red wires for free whether built by bots or manually by you... so you can actually get this advantage for no additional cost over the cost of a simple belt.