TL;DR
Container should have an output signal for the number of free slots in the container.What ?
I'm suggesting the following changes for Mode of operation for chests:- Read contents
- Read contents (stacks)
- Report space for items
- Report space for items (stack)
--- - Report empty slots as <name of signal>
The last option should be selectable in parallel with one of the others and the signal (default S) can be chosen by the user.
It would be nice if a container reported space for all possible items as it would be difficult (impossible?) to separate no signal (container doesn't have any of an item) and 0 space for an item.
Space for items should honor filtered slots. A slot filtered for iron plates would count as 100 iron plates space (when empty) but would not be counted for e.g. copper ore. An empty container can therefor have different free space for each item (even counting stacks).
The report of free space in stacks should round down. That way a full stack can be added when the container says there is space for one. There might be more space but never less.
For train stops similar additions should be made to report the train contents (or lack thereof). Same goes for tanks and fluids.
Why ?
To make more efficient trains I'm enabling the station only when the buffer chests have enough free space to unload a full load. For this I need to sum up the amount of space in a chest according to the stack size of the item and then subtract the size of a wagon load, again depending on the stack size of the item. And when I change the number of type of chests I have to recompute the value all over again. It would be nicer if the chests would output the amount of items that can still be added. It would also be nice to get the number reported in stack sizes. That way the circuit condition could be specified independent of the item stack size and chest size.In this example the condition for receiving Iron Ore would be "Circuit Condition: Iron Ore >= 40" for a full load.
With the circuit conditions independent of the buffer chests and item stack size the train stations can be blue printed without having to compute and adjust the condition every time and buffer chests can be upgraded over time without breaking the circuits.