factorio

Logistic Trains Without Logistic Bots

Hello again! It’s been another long while since my last post and I’ve played a few more Space Exploration games since then.

A problem I keep encountering is the massive gap between unlocking basic bots and unlocking logistic bots in SE making the logistic train circuits in the prior posts useless. Because I’ve already “solved” the end-game logistic train circuits I kept trying to push through this gap without using midgame logistic trains/circuits with little success.

It’s difficult to go back to the pre-logistic train solution with all the assocated problems, limitations and annoyances. After a lot of experimentation I’ve adapted the end-game logistic train circuits to work without logistic bots. I find it works very well for me though the throughput is limited compared to logistic bots and requestor chests. When I unlock logistic bots I’ll be using requestor chests again.

Here’s a preview of the finished depot with the loading stations for each logistic train type:

And the unloading station that supports up to 3 logistic train modules:

They can also be upgraded to their end-game forms independently, the modules and trains are common between mid-game and end-game circuits.

The Loading Stations

The “SEED MODULE” top-left is a train station and combinators for the seed train logistic module. The module is shared (copied) between the loader and unloader. There is a red and green side. Two constant combinators per side allows up to 40 unique items per wagon matching the 40 slots per wagon. The red and green manifest signals are put on the lower substation red and green wires which signal the buffer chest circuits and the loader circuits.

The lower loader circuits are detailed in the prior posts and do exact insertion with a hand-size signal as well as item set-filters signal to the inserters.

The above buffer chest circuit inserts the target items into the buffer chests if found on the belts near the buffer chests.

The target level in the buffer chests is a small multiple of the manifest signals (x4) to ensure a few trains can be loaded in quick succession before the slower fill-up from the shared depot storage catches up which is limited to the throughput of 1-belt and the time to switch between item types.

Missing items in the buffer circuit set the green signal on the depot storage to request the ring-belt around the storage warehouses is filled with that/those target items. A pair of whitelist inserters and pair of blacklist inserters on each storage warehouse add and remove wanted and unwanted items from the shared ring belt one item type at a time until the buffer for that item is filled.

This shows the storage to station interface in more detail. The top two arithmetic combinators act as a diode to prevent station signals being mixed from the aggregate depot signals. The third puts the missing items (requested) items on the green storage wire.

The depot signal is used to set the target item level in the shared storage warehouses. Missing items are made-to-order in the mall above via the red signal (shown elsewhere).

This belt from the storage to the buffer wagons is also very important as it helps reduce the number of item switches on the storage warehouse ring belt. It takes 10 seconds or so for the requested item to appear then saturate the storage ring belt for each item type requested. If requesting 80 item types, it would take a minimum of 800 seconds to refill buffers. However if you do more work per item switch you’ll need to switch less. In the seed train there is a diverse set of common items configured (inserters, chests, power, bots, etc) and the ~30 belts of delay between putting an item into the station circuit and putting that item in the buffer chest allows up to 240 additional items to be buffered during that context switch which for some items and trains may mean re-loading every 4th or 5th train.

The minimum work per item switch can be increased by increasing the length of the belt and delay between the storage and buffer chests, assuming you have enough buffer chest storage slots left.

The trash station is shared between all logistic trains to reset them back to a good known state (empty). Some select items (wood, coal) are converted to fuel to power the logistic trains and others (barrels) are re-filled with oil for the wall flamethrowers.

The “RED MISSING ITEMS” shows the simple difference circuit that requests new items from the mall.

This is my mall that creates the missing/requested items for the logistic depot.

The depot supports multiple logistic train types. In this playthrough I have a “seed” train with generic common items, “outpost” with mining and factory items, “wall” which contains wall items and “raid” items for taking out nests.

The module and loader station are customized and configured per train, the rest is common.

The Unloader Stations

This is the unloader station with room for 3 modules (or train types). Items are unloaded directly into the storage chests and trash items loaded back into trains from the storage.

Because my trains are unidirectional I can’t guarantee the arrival orientation of the trains, so construction and logistic bots are moved from the lower to upper storage chest to bootstrap the bot network.

This is showing the seed module was placed, it detected the storage is missing seed items, the seed train was dispatched and seed train is currently unloading.

Compared to the prior stations in prior posts the thresholds have been updated to (1) request a train if item count below 100% target (2) unload items up to 200% target (3) items above 300% or unknown items request a trash train to return items to the depot.

Previously I’ve requested trains at <100% and >200% but found that it’s too sensitive a common case where I’ve only used a few items (chests, wire, jetpack fuel) and a full train is dispatched to replenish 5-10% of a few items.

Now I’m re-filling at least one full item type per train dispatch.

Save File

If you want to play with it in action I’ve uploaded my current save game. You’ll see I’ve massively overbuilt on Nauvis and not even launched my first rocket at 120 hours in. I’ve had a lot of fun working on logistic trains instead.

2024-02-04-mason-se.zip

Go to one of the wall stations and start building some stuff, or adding and removing modules from the station to see the depot and trains do their dance.

No blueprints for now as it should be simple to copy what you want/need from the above save game. My rail blueprints can be found in prior posts.

Bugs & Feedback

Please raise an issue here or email mason.larobina@pm.me for any corrections or improvements.

Discussion

Enjoy! 😁