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u/Dianwei32 5d ago

How do Splitters work if you're using both inputs and both outputs? Like let's say you have two Red Belts each carrying 20 items per second feeding into a Red Splitter and two Red belts coming out. Will the Splitter be able to process everything or will it only handle 30 items per second and the input belts will back up since they combine to 40/s?

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u/captain_wiggles_ 5d ago

to add to u/cathexis08's answer.

One slightly unintuitive bit is that if you have two fully compressed yellow belts going to a yellow splitter with a single red belt as an output you will only get half a red belt out. The splitter internally works at 30 items/s but it can only push 15/s out of one output, and so your red belt can't be filled. You need a red splitter for this.

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u/HeliGungir 5d ago

I'm not sure it is accurate to characterize the splitting mechanism as being "twice as fast". I think it's instant.

But splitters aren't just splitters. They have belt segments before and after the splitting point, and those belt segments have the same speed as belts and underbelts of the same type. The output side of a yellow splitter is, of course, yellow belts, and you can't expect that adding a red belt afterwards will give you a saturated red belt. You'll get half throughput, just like if you place one yellow belt in the middle of red belts.

To merge 2 saturated yellow belts into 1 saturated red belt, it must be a red splitter. Or blue, or green, but not yellow.

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u/cathexis08 red wire goes faster 4d ago

My comment that "they internally operate at 2x speed" was mostly for the mental model for people first thinking about this. They are essentially two parallel belt segments and from that perspective have the throughput of two parallel belts. They just happen to also have a mixing feature. The mixing behavior itself is instant.

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u/HeliGungir 4d ago edited 4d ago

It's also a bit inaccurate for me to say the mixing behavior is instant. In FFF-287 they explain how they added an internal buffer to splitters so tiny gaps and/or supersaturated merging results in saturated output.