Factorio Forums

On other machines (e.g. assemblers) you can connect the machine to the circuit network, set it to "Read Contents", and the use the count of the contents (inputs and outputs) elsewhere in the network. This doesn't appear to work for Foundry's though (possibly other fluid producing machines but I didn't test them).

I would've guessed it was just intentional and that you're supposed to output to a tank, and read from there, however; the volume/count of fluid shows up as an "input signal" on a combinator connected to the foundry. The value of that signal is just not used in the Conditions on the combinator.


You can see here, the combinator connected to the Foundry
And here you can see the input signal showing 540 molten iron, but this value doesn't register on the condition - which should've been enabled by the value > 500.

Given the screen from decider combinator i can tell you that foundry works just fine, the issue is of different type and it is the same one as 118474 - there are 2 separate signals with the same icon (molten-iron fluid and molten-iron recipe), machine gives you molten-iron fluid but you are checking for molten-iron recipe signal which has value of 0. We are still thinking how to fix this in a least confusing way. Duplicate of the mentioned topic.

You are, of course, totally correct. As soon as I switched to the other, correct signal everything worked as expected. Thanks for pointing me at the solution!