Factorio Forums

Repeatable example: using circuits to set the recipe on a foundry:
- Flips the pipes to the right side when set to Cast Iron (inputting fluid).
- Flips the pipes to the left side when set to Molten Iron (outputting fluid).

Reason this is an issue: trying to make a compact, circuit-controlled foundry that switches between molten and casting, but the pipes need to stay flipped in the orientation it was built in.
Possible reason it happens: this may be because the machine tries to avoid making an input and output on the same side for fluid mixing avoidance reasons, but in this case it is the same fluid type.
Possible solution: Something like a check box for enable 'keep fluid orientation' could fix this.

It may be worth checking: if this applies to assemblers, chemical plants, and other fluid-using machines with recipes.

That is the correct behaviour. Foundry does not rotate or flip when its recipe is changed, be it manually, or via cirtuit network.
As you've noted, those two recipes differ how they use fluids, one is inputting them, the other is outputting them.

Lets take other pair of recipes - heavy oil cracking and light oil cracking.
Heavy oil cracking takes heavy oil and water and outputs light oil. Light oil cracking takes light oil and water and outputs petroleum gas.
Now imagine you switch the recipe from heavy oil to light oil. Currently the water input stays at the same place, other fluids change.
According to your idea, heavy oil+water inputs get replaced by petroleum gas outputs and light oil output gets replaced by light oil input + water input.
IMHO, it's way more messy.

I'm not sure why this is a problem - I have a fully automated foundry on a ship. Yes it looks odd that pipes connect a disconnect, but it works and TBH it is expected that input would stay on one side while outputs stay on the other. Inputs seem to be assigned ingredient order as are products.

If you want multiple fluids supported than the problem become dealing with ingredients in the order given as selector combinators sort stuff into amount order asc/desc.

As for dealing with the fluid changing, you need pumps to present and clear the fluids. I tried to get multi-fluid in/out working, but until there is a way to get an ingredient in ingredient provided order or by index, it seems to be a non-starter. Selectors need a none sorting or specific ingredient indexing option.

Not a bug