Factorio Forums

Hi,

I'm struggling trying to figure out how LTN works in some cases. I've been experimenting with it, and i think I've figured out most things, but I'm still struggling with a couple of issues. One of those issues is a problem I'm having with stations that provide multiple items.

As an example, I have a station that provides both steel ingots and steel plates. I have wired up inserters that read from the LTN Station Output and have filters set so they grab items matching the train request. At least, this is how I thought the LTN Station Output was for, but if the train turns up with some leftover items, then those leftover items show up in the Output, and the inserters try to unload this item. This either leads to a train sitting and timing out because nothing gets loaded, or if there are a few leftover of the other item in the station, then it starts getting loaded and is then full of the wrong item.

What is supposed to be showing up in the Output? I thought it was the amount of the requested item, but it sometimes seems to show the contents of the train as well. I thought you had to wire to the train stop itself and set Read Train Contents to get that, so I don't get why it's also showing on the output. Might I be wiring things up incorrectly? (I know I should be making sure that trains are empty, but that's a longer term task as I need to figure out which stations are malfunctioning...)

Maybe you have a look to those sample stations again:
viewtopic.php?f=214&t=51073

The output of LTN stop shows the expected train inventory (and some train composition stuff).
F.e: A train gets scheduled to pick up 8000 iron ore.
At provider station it shows f.e 8000 iron ore, because the train should contain 8000 iron ore after loading
At requester station shows empty, because the train should be empty after unloading

This, combined with the actual train content via Read Train Content from the stop, can be used to control the filter inserters.

At provider station, you calculate:
expected train inventory - actual train inventory

At requester station, you calculate:
actual train inventory - expected train inventory

I guess your problem is, that the leftover material is shown as expected train inventory, because it should stay inside the train. So in this case, its important to substract the actual train content.

Ah, thank you! You have clarified the issue for me, I had misunderstood.