Logistics storage

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ikarikeiji
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Logistics storage

Post by ikarikeiji »

This is a problem I've been trying to solve for a long time and never found an answer to.

Suppose I have an iron smelting area, connected by belt to something using iron all the time... let's say module production.

I have some random other things in my base that want to use iron, let's say destroyer drone production, and don't want to connect them by belt, so, ok, I put a passive provider where the iron comes out of the smeltery and a requester chest on the input to the drone production area. So far so good.

Now I also end up with random bits of iron from time to time when rearranging my belts, and I want to put them in an active provider chest to get rid of them. But then they go into a storage chest, I want them back on the belt.

If I just put an iron requester chest next to the passive provider chest then bots constantly fly between them moving iron from one to the other which is not what I want.

I have tried messing around with smart inserters and wires, with a flip-flop that turns on or off depending on how much iron is in the logistics system and pulls in or pulls out iron depending on that, but I just can't seem to make it work in all cases.

I feel like there's got to be a way to do this (that doesn't use the combinators coming in 0.12), and it's such an obvious requirement, has anyone managed this somehow?

johanwanderer
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Re: Logistics storage

Post by johanwanderer »

This may be what you are looking for:
20150712-03-smart-provider.png
My logistic buffer for the iron lines. I have an identical setup for the copper lines, just above it.

To the left, there are two requester chests, each requesting 1K iron plates. They are both hooked up to the red signal network.
To the right, there are four passive provider chests filled by smart inserters (pictured), which are also hooked to the red signal network.

When the belts are packed, both sets of chests will fill up. When the belts start to run thin, the requester chests will be unloaded, and because they are no longer full, the smart inserters will not fill the provider chests until they are backed up to capacity again.

Because I hate cluttering of the logistic storage, I also place requester chests for intermediate products (coils, iron sticks, etc.) next to machines that use them, to make sure that whenever I deconstruct something, or just dump my inventories into an active provider chests, they all get cleaned up quickly.

This is the logistic storage of my manufacturing base:
20150712-04-logistic-storage.png
Hope that helps!

ikarikeiji
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Re: Logistics storage

Post by ikarikeiji »

Hmm... Nicely done, and good idea with the requester chest for copper cables and so on. It's not EXACTLY what I was looking for though; your system will create a buffer in case the supply runs thin, but what I was after was a system whereby any iron in logistics storage - apart from the passive provider chests - would be placed onto the belts, and take priority over iron that had just been mined and smelted. Basically just to suck any spare iron out of the system even if supply is already fine.

What I was trying to do with smart inserters was make it so that it would only take out of the requester chest if there was more than the number the passive providers + requester can store in the logistics network, therefore the bots would take from storage/active providers first and leave the passive providers alone. I couldn't get this to work though... but when I think about it now I can't think of why it wouldn't work, maybe I'll try it again...

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Tallinu
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Re: Logistics storage

Post by Tallinu »

Set the requesters to some small amount like 50, then have smart inserters fill the passive providers when logistics storage levels of iron are below 999, and empty the requesters when storage of iron is over 1000? That should result in any excess amounts in storage getting shifted gradually into the requesters and onto the belts until only the amount in the passive providers remains. But as it's consumed and refilled, storage may briefly go over 1000 and result in some being taken out of the requesters, leading to a small transfer from providers to requesters, which may trigger a repeat. So the numbers used are examples off the top of my head and may require adjustment. You may end up having to live with some small amount (like a fraction of a stack) occasionally ending up in storage until other requesters pull it out, in order to provide enough difference between filling and emptying levels so that constant transfers aren't happening.

If it's too hard to get the requested iron onto belts, unload it onto a separate belt and merge it in using a splitter. That will guarantee that 50% of the iron supplied will come from the requesters instead of the furnaces, until they stop unloading.

johanwanderer
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Re: Logistics storage

Post by johanwanderer »

ikarikeiji wrote:What I was trying to do with smart inserters was make it so that it would only take out of the requester chest if there was more than the number the passive providers + requester can store in the logistics network, therefore the bots would take from storage/active providers first and leave the passive providers alone. I couldn't get this to work though... but when I think about it now I can't think of why it wouldn't work, maybe I'll try it again...
Ah.. I see now. I think the issue may be in the placement of the chests. If you have requester chests "upstream" of the provider chests, i.e.:

Code: Select all

>====>====>====>====>
R             P
You end up creating a loop between requester-> belt -> provider -> robot -> requester, and the bots will keep trying to supply the ever-emptying chest. On the other hand, if you switch the requester to be downstream of the provider (reverse the R & P chests, above) then you won't have that issue.

ikarikeiji
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Re: Logistics storage

Post by ikarikeiji »

Turns out I was overthinking it. Here's what I ended up doing:

Image

The belts coming from top left and going out at bottom left just come off the main iron line and back on via splitters.

The top chest requests 100 iron, the smart inserter below it facing down only moves iron if iron in the logistics system > 200. The bottom passive provider chest has a limit of 2 stacks so 200 iron, and the smart inserter to its left facing right only moves iron if iron in the logistics system < 200.

The steel chest in the middle has no limit and acts as a buffer if lots of iron suddenly appears in logistics storage but there is no demand for it right now.

When there is demand the steel chest will empty pretty quickly and no iron will come in from the left.

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