I'm trying to set chemical plants to switch plastic recipes (between the butane and petroleum recipes) based on available hydrocarbons.

There is a circuit symbol for the 'plastic (butane)' recipe.

There is not a circuit symbol for the 'plastic (petroleum)' recipe. I tried using the 'plastic' symbol instead, but it sets the plastic (from bits) recipe.

So either 'plastic' should infer the 'plastic (petroleum)' recipe, or there should be a circuit symbol for 'plastic (petroleum)'.

Thanks for the mods!

This is caused by an engine limitation; Factorio somewhat arbitrarily decides what recipe a given signal will produce, and our ability to assert another preference is limited. There is a proposal to deal with this but the devs have so far not responded.

Anyway, I've added a workaround in Scrappy Industry 1.1.4 so this particular recipe should work, but the underlying problem is currently not fixable.

Thanks; your work-around is good enough for me.