However, this presents a problem. Overproduction of any one item type can quickly saturate this depot and grind the entire factory to a halt, and manually setting 1000 circuit conditions is neither fun nor realistic.
To solve this, most people opt for bot-based designs, but these are expensive, often feel overly simplistic, and still require setting a specific condition for every item type.
Another problem comes when dealing with fluids. No tank can hold multiple fluid types, and one cannot flush pipes to route multiple fluids down the same line. This makes a centralized fluid depot near impossible.
AutoTrainDepot solves both of these problems.
It allows you to use a belt-based train depot for items, by automatically managing the conditions and I/O inserters as necessary. It also can manage which cars are input and output, so that the trains, if they are to both pick up and drop off items at a depot, do not fill their "output" cars with already-stocked items.
It also allows you to control trains' fluid connectivity on a car-by-car, train-by-train basis, allowing for a depot to store and distribute up to six fluid types to and from any trains it services.
AutoTrainDepot also has a feature to alert players when their trains get stuck, either from invalid pathing or from a multi-train deadlock:


Demonstrations of the item and fluid depot controllers:
https://www.reddit.com/r/factorio/comme ... events_to/
https://www.reddit.com/r/factorio/comme ... the_fluid/