Factorio Forums

Hello. So I was trying to understand how these things work. It really doesn't help me that there is over a gazzilion Reddit threads and YouTube videos, each claiming their design is the best and most superb. Can someone please point me towards a thread or video where the best possible Priority Splitter designs are being used/explained, please? Thanks.

Hello? Can anybody help?

https://wiki.factorio.com/Balancers

iam pretty sure you wont get any answer you wil like. Every design has its dis/ advantages and i doubt thet the increased undergroundbeltlenght wil have a any noticable impact inbalancers. Just use anyone until you get to grasp teh system and make your own.

You aren't getting many replies because most Factorio players aren't using priority splitters yet. To most folks, a good belt balancer is still cutting edge tech. The existing videos and posts are really all there is, so far.

well, it's more that priority splitter designs (thus far) don't work nearly as well as splitter-based designs under all types of load/throughput conditions. i use the design on the right when i want to pull a full belt off a 4-lane bus. (design from /u/lordpeppe on reddit.)

AFAIK this is the state of the art for a priority splitter:
HOW TO ACTUALLY USE A MAIN BUS PROPERLY - The Priority Splitter 2 - Factorio Tutorial
a Youtube video by Steejo published on 19 Sep 2016. It includes a variant created by a Factorio dev (but the core concept is the same as Steejo's just rotated 90 degrees).

I posted an earlier design in another thread and was pointed to this version.

As far as I know, the best and simplest priority splitter is a single wire after your splitter.

Video linked above uses this approach, though with so much useless stuff on the screen it might be hard to understand how simple the basic idea is.

You use a single wire (red or green) to connect both belt tiles after the splitter. One of them will be prioritized, the other won't.

You need prioritized belt to always run, so you click on it, remove blocking operation mode and set it to read contents in holding mode (so the signal is generated continuously).

Other belt is left in enable/disable mode, it must NOT read belt contents (so the wire only counts items on the prioritized belt tile). The condition for enabling is that resource that you're carrying on the belt is greater than N, where N will usually be within 2-6 range depending on whether your prioritized belt is straight or corner, whether the resource occupies both lanes or only one lane and which one specifically. Just tune the number to ensure that the second belt only activates when prioritized belt is fully occupied (whatever "fully occupied" means in your specific situation).

Essentially, for as long as the feeding belt is only partially filled, low-priority belt will always stay frozen and entire traffic will move into the prioritized belt. When feeding belt is compressed, low-priority belt will periodically unfreeze, leaking some of the items through. If priority belt is backlogged, low-priority belt will work full-time.

So much for splitting a single belt. When doing a priority split from a multi-belt bus, what you do is create a sequence of priority splitters that will shift your entire bus contents to the side from which you'll be doing the split, starting from the farthest side and ending with the actual splitter that diverts resources from the bus. This creates a characteristic "staircase": splitter + 2 wired tiles on belts 1/2, same on belts 2/3, same on belts 3/4, and finally belt 4 is priority-split to the side. This is done to ensure that a resource that is scattered among 4 belts in low amounts is concentrated on the rightmost belt before being priority-split, and this is exactly the design you see in the video linked above.

Remember belts have a fractional number of items per segment... if you only detect one belt segment, the value of items will "flicker" and reduce the max throughput of your splitter. For a max throughput priority splitter. you need to use the method above, but wire (i think) 9 detector segments of belt together to easily read a complete whole number when the belt is fully compressed. Of course you would need to up the value on the disable-able non-priority output belt to account for the new value.

Lav wrote:Essentially, for as long as the feeding belt is only partially filled, low-priority belt will always stay frozen and entire traffic will move into the prioritized belt. When feeding belt is compressed, low-priority belt will periodically unfreeze, leaking some of the items through. If priority belt is backlogged, low-priority belt will work full-time.

This is the exact problem "periodically unfreeze" which occurs in:

AndrewIRL wrote:I posted an earlier design in another thread and was pointed to this version.

and you can find in Steejo's earlier video. It can't differentiate between a compressed flowing belt and a backlogged belt leaking items (about 1/8th) onto the lower priority belt. The linked video explains this and why you need three belts connected in circuit - you need an independent backlog detector.

Looks like the design originated with rasby:
viewtopic.php?f=202&t=32817

The two circuit connected belts on the left are the backlog detector.

Thanks guys! Really!