Train station can also read locomotive contents when 'Read train contents' is turned on

[Gradenkos]

TL;DR
Title says it almost all.
The checkbox to include the locomotive should be separate.

Why:
I dislike the fact that when I delete a train I get 300 of the fuel in my inventory.
I want to be able to use an inserter to only fill the locomotive with a limited amount of fuel.
As you use a more 'expensive' fuel you might not have enough to fill all your trains immediately to the brink.
With this option you can divide it equally between your trains.

Also:
Read somewhere people use a number of fish to identify the train and whether to unload e.g. coal or iron.
This way you could put those in the third fuel slot and not take up a valueable cargo slot.

[Koub]

All these threads suggest solutions to the same issue (need to be able to read the locomotives' contents and the wagons' contents separately to control fuel in the locomotive) :
viewtopic.php?f=6&t=59114
viewtopic.php?f=6&t=46732
viewtopic.php?f=6&t=51387
viewtopic.php?f=6&t=52484
viewtopic.php?f=6&t=70171

Also there are mods that should fulfill your need (I play vanilla, so I have never tested them) :
https://mods.factorio.com/mod/Inventory%20Sensor
maybe https://mods.factorio.com/mod/FactorIO

[Tekky]

As I have already stated in some of the threads mentioned above, I think the following suggestion offers the best solution:

viewtopic.php?f=6&t=51387 Rail car/locomotive scanners

That way, you would be able the contents of individual locomotives/wagons with the circuit network.

[Gradenkos]

Thanks.
Did search for 'station, contents and read'. Forgot that people will use synonyms instead of the terms actually used ingame.

Tried the 'inventory sensor' mod and it's too slow... An inserter wil already insert fuel in the train before the 'inventory sensor' senses the contents of the locomotive. Even if you put the sensor a couple of rails before the inserter.

[DaleStan]

To use Inventory Sensor, you need to make sure the inserter is disabled until the Inventory Sensor reports that there's an engine in front of it.