Factorio Forums

TL;DR

Construction bots should only pick up an item from a landing pad when it is not available anywhere else in the network. Today, without this, deconstructed buildings that are shipped in via spaceships slowly accumulate on the planet.

Why?

Logistic bots follow a clear priority when it comes to deciding where they pick up an item. However, construction bots apparently do not care. This causes a problem when space age interplanetary logistics enter the mix.

Let's say you are shipping electromagnetic plants from Fulgora to Nauvis (as they cannot be built on Nauvis). The landig pad on Nauvis is set up to request 100 electromagnetic plants. Now you start building stuff on Nauvis, placing electromagnetic plants and deconstructing them again as well until the design works as intended. What will happen is that many times, when an electromagnetic plant is to be placed, it will be picked up from the landing pad, but when an electromagnetic plants is deconstructed, it goes into storage. The result is that electromagnetic plants slowly build up in storage, where they never will get used since the bots keep using the new electromagnetic plants in the landing pad instead.

I strongly think that construction bots should only pick up an item from a landing pad when it is not available anywhere else in the network. That is the only way I can see to avoid this issue of accumulating "old" plants that the bots will never place.

Just to add documentation, here's what the wiki says about this:

https://wiki.factorio.com/Logistic_network#Construction

When construction robots want to build a ghost, they look for the chests that is closest to the ghost they want to build. The type of chest does not matter.[2]

That "2" links here:

viewtopic.php?p=569235#p569235

Currently, construction bots try to find the chest that is the closest to the ghost they want to rebuild.

Idea is, that players want to bluprints to be built fast, so construction robots shouldn't travel over large distances (system that manages this is still pretty simple, though, so it's not that great) ... and you can use buffer chests to make logistic bots bring items closer to the construction site and construction bots will use the closest chest.

You could use a little circuit contraption to read the number of items in the logistics network, and only request more from space when you are running out of local supplies.

You could use a little circuit contraption to read the number of items in the logistics network, and only request more from space when you are running out of local supplies.

Hm, I guess that could work... though I feel like it really should not be needed.

EDIT: One problem though, since the contents of the landing pad will count as also being in the logistic network, that means the request will be 0 when it is fully satisfied. That means I cannot use "trash unrequested" for the landing pad as it would trash everything. So when I trash stuff from orbit it'll accumulate in the landing pad and fill up the space there...

Put three buffer chests around the landing pad and request a few of each building being imported?