Decider combinator, set recipe

[pn90]

Hello,

I'm new to this game, and I've been playing it completely without any guides, tutorials, or spoilers in general. I want to experience the game that way.

Currently I'm testing/playing with the circuit network. So, when I thought I had figured out the Decider combinator, I realized I actually hadn't.

The problem that occurs is output signals; the setup photo is in the attachment. The input of the decider combinator is a box where I store solid fuel/sulfur directly from a chemical plant, and its output is the chemical plant. You can see that the first signal is sulfur, and when I click "Set recipe" in the chemical plant, it starts to produce solid fuel (I thought it should produce sulfur). When the solid fuel becomes the first signal, it still continues to produce it.

So basically, my question is, what is the first valid recipe signal, or the first valid item signal, or the first valid entity signal as described in "Set recipe" in the chemical plant?

PS - the Switch 2 version with Joy-Cons is great (especially on TV); 101% recommend

[Loewchen]

First signal is the signal with the lowest signal ID, you have no control over it in this setup. The setup as is has no actual purpose, the condition will always be true and the outputs will always be the inputs so this is essentially just a fancy wire. You said you did not want a guide, so I am unsure if you want to know anything further.

[Kyralessa]

You may want to take a look at the selector combinator, which gives you some options for sorting signals.

[Tertius]

what is the first valid recipe signal, or the first valid item signal, or the first valid entity signal

Signals have an internal sorting order. If you open the signal picker dialog, signals more to the left, more to the top have higher priority, and if they're on different tabs, signals on tabs more to the left have higher priority. So the highest priority ("first signal") is the wooden chest, and the last one is the "WUBE logo (space platform)" on the bottom last tab.

A recipe signal is a signal representing a recipe but no item. For example there is a "basic oil processing" signal. This is a recipe signal.
An item signal is a signal representing some physical item that's not an entity, for example iron plate as well as water or light oil.
An entity signal is a signal representing some physical entity. That's something that can be built on the map such as a furnace or an assembling machine.

An item or entity signal can be seen as recipe: craft this item. An item signal will use the default recipe for crafting this item. If there is also a recipe signal for crafting the same item, this overrides the item and specifies which recipe to use to craft, because all recipes are more to the left/top than the corresponding items they craft.
The ordering of the types in the popup text in your screenshot is not relevant, it's just a text to explain what can be used to set a recipe in general. What matters is the ordering within the item picker.

Solid fuel is an example for this, it has 3 different recipes and 1 item signal. If you send a solid fuel signal, the chemical plant will use the "Solid fuel from petroleum gas" recipe. If you additionally send the "solid fuel from light oil" recipe, it will use the "solid fuel from light oil" recipe, because a valid recipe signal has precedence over the item signal (more to the left). If you continue to send the "solid fuel from light oil" recipe and instead of the solid fuel item signal you additionally send the "solid fuel from petroleum gas" recipe, the plant will use the "solid fuel from petroleum gas" recipe, because both are recipes and the petroleum gas recipe has precedence over the light oil one (more to the left in the signal picker).

There are also items without default recipe, although a machine could do something with it, for example the fluid barrels. If you send the water barrel item to an assembling machine, no recipe is being set. The assembling machine will not decide if it should use the fill barrel or empty barrel recipe.

Even if you don't want to consult guides, I recommend you consult the wiki if something isn't clear from the game alone and you're not able to figure it out from trial & error within the game. You can search for ingame items and skip everything else that might be a spoiler, and there are useful articles about the game mechanics. If you want to know more and are unable to figure it out from the game, this is the place where you find more information.

[pn90]

Hello again.

First, thank you for your answers.

I unlocked the selector combinator and tried a different setup now; however, the similar problem still persists.

Input is a wooden chest with 50 sulfur and 50 plastic.

The selector combinator is in random input mode (so it's 50%/50% sulfur and plastic output, which changes every few seconds).

Output is the chemical plant.

All the needed ingredients are available and connected (2 pipes, water and gas, and coal)

When I check the set recipe, it starts to produce, for example, sulfur, then switches to plastic after a few seconds, and when it wants to switch to sulfur again, there is a leftover of coal from plastic, and it stops producing (I know I can remove leftover coal with an inserter, but I really don't want to because it isn't sustainable ).

So if anyone knows how to produce 50/50 sulfur and plastic without any leftovers, please tell me. I tried a few other things but unsuccessfully (I suppose maybe an inserter can be configured to only insert coal enough for a recipe, but I don't know how).

[Tertius]

If you switch recipes, you always have to implement a means to remove ejected ingredients. Usually, they're being removed along with the expected output, so you can filter them and feed them back to the input. You can also remove them with a dedicated inserter with a proper filter.

But trying to inserting exact amounts isn't feasible. Don't do it. Even if you think you found a proper circuit, it will fail for some reason in the long run. There are edge cases where any such circuit will fail. Such a solution isn't robust, because it always needs manual intervention if it fails.
A supposedly bullet proof circuit contraption will also need more space. More space than building 2 dedicated chemical plants with static recipes need in the first place.

Finally, the demand for sulfur and plastic bars is vastly higher than for 1/2 a chemical plant, and you need both simultaneously and continuously, so building multiple dedicated chemical plants is not only the most simple but also the best approach.

If you want to get into the circuit network, find a different challenge, for example with balancing production of all the oil products (heavy oil, light oil, petroleum gas).

Or build a gauge with 10 lamps to visualize the filling state from 0..10 of some storage tank or of some chest. Optionally with color change from red (0) though yellow (5) up to green (10.

Or build a global circuit wire that collects signals of all content of all your storage chests, so you know how many items you have in storage in your whole base. Then define a list of these items in a constant combinator with the desired amounts of these items. And then subtract one set of these values from the other so you get the difference of your actual stock and the desired stock. And then activate any machine that produces items in demand and deactivate any machine to stop production of surplus items.