Help! LTN stops getting mixed items?

[NewtypeWoman]

Hi! I had all my stops set to use basic two car one item setups. Very few conditions, beyond very high provide and request thresholds, usually around 3000-4000 per item, and the only items that were in the system were coal, stone bricks, iron plates and green circuits.

This went great for several hours until, while building a uranium refining setup at a faraway outpost, I came back to the main base to discover the entire iron lines had been filled with stone bricks and iron mixed.

No clue why this happened, could someone tell me why it might have and what I can do about it?

[Henk Zaan]

I had the same problem. LTN send the trains to the requester stops for loading instead of unloading, dumping the wrong articles in the wrong requester stops and so on. At first I thought that my settings were wrong, however it worked for several hours correctley. I deleted all the trains, clean the requester stops from the wrong items, set one by one a train with orders and followed them some while. No problems again. I filled the whole system with more trains and then I saw that again the trains went to the wrong stations. I deleted now the trains and set it manual with per request station only 1 fixed train.

[Optera]

The most likely source of pollution is providers overfilling wagons, with inserters stuck with item in hand.
Use the locked slots per wagon control signal and smart station designs for loading and unloading.

[ssilk]

Because errors can always happen I recommend also this: at the depot connect to the output of the train stop. If there is anything in the train (besides itself) give an alarm and stop that train leaving by a signal.

This is essential with fluids, because once you get remains into tank wagons everything goes wrong.

Debug this kind of errors then: just go back to (autosave) and look where that happens, or look into the log of ltn manager mod. (?Not sure, if it is possible to see the way of single trains through the previous stations, because I turned it off, because it eats me too much cpu, about 10 UPS)

For depots where only trains with wagons appear it worked also well to make this kind of alarm, but also trigger unloading wagons into active provider chests and the outpost with the depot just needs to handle the rest itself.

If needed I can provide some blueprints.

[KrazyTygr]

... LTN send the trains to the requester stops for loading instead of unloading...

I used to have this problem, and solved it by setting the requester station with the normal request threshhold, as well as an extremely high provide threshhold (a value higher than the station can physically hold). This provide threshhold will never be reached, so trains will not try to use it as a provider.

[Henk Zaan]

... LTN send the trains to the requester stops for loading instead of unloading...

I used to have this problem, and solved it by setting the requester station with the normal request threshhold, as well as an extremely high provide threshhold (a value higher than the station can physically hold). This provide threshhold will never be reached, so trains will not try to use it as a provider.

That is a good sugestion to set the provide treshhold extremely high by requester station's. I am going to try this. Thnx.

[ssilk]

It’s sometimes really hard to find the reasons for such errors, because the system works perfect when testing, but under load you get sudden errors. So in the beginning you don’t know what you are looking for. I found me sometimes replaying a map over 10 times to find the one microsecond, when the error happens. There is some hours of no problem, and suddenly one train is loaded wrong, but you see it only, when it is much too late and need to load an old save and try to run fast enough to reach that stop in the time it takes for the train.

Would be useful to have some kind of debug mode, but for now I use the temporary stops: I reprogram that stops so that train waits for person loaded, so it will wait in front of target stop and when you enter it continues and you can look, what goes wrong. Would be simple to build that into LTN; add such a flag per stop and when it is preset it adds such a wait to the temporary stop in front of the target.

Similar stuff when leaving: when the debug was present and the numbers of items/fluids in the train differs too much from the targeted items (or train is not empty), just stop train and make an alarm. This gives the player the chance to see, when the problem happens, and not so much later.

[Optera]

Yet another debug mode is not going to happen.
The design thread has stress tested designs proven to work for years.

[ssilk]

Not for working designs. That is boring. If I want to build new designs. Or change working designs. Nothing is perfect, everything can be improved....