Read contents of splitter by circuit network

[teenkertoy]

TL;DR

Please allow the real-time contents of a splitter to be read by circuit network.

What ?

This is not the same as another topic asking to control splitter priorities (yes I tried searching). I am more interested in reading the real-time contents of the splitter similar to reading contents of a belt.

Why ?

There are many clever ways to use the circuit network to control the contents of belts, but it relies on knowing the real-time contents of the belts. Sushi belts are a good example, specifically for lab research. Some of the techniques rely on splitters somewhere, and if their contents cannot be read by the circuit network then control is very difficult to achieve since there is a blind spot in the system that you are trying to control.

[Tekky]

The same problem also exists for underground belts, as they also cannot be connected to the circuit network. That way, both splitters and underground belts cause gaps if you are reading belt contents in hold mode. However, you can work around this problem by using pulse mode, as has been discussed in the following thread:

viewtopic.php?f=5&t=49729 Underground Belts, Splitters & The Circuit Network

I'm not sure if it would be meaningful to read splitter contents by the network, because, in order for the information provided by the splitter to be useful, it would have to provide 3 separate signals:

1. splitter belt contents before the split
2. splitter belt contents that has been split left
3. splitter belt contents that has been split right

[jcheung9941]

now that "hold (all belts)" is a thing, i'd really like it if "all belts" also hit the splitter either on input or output (one or other but not both)
looks like it handles undergrounds okay

[Tinyboss]

I was about to suggest the same, but found this thread when searching. Here's my take:

• It should NOT be included in "all belts" for connected belts. We can very easily connect it ourselves with circuit wire to any combination of the input belt(s) and output belt(s).
• We need all the belt reading options, plus a selection for left, right, or both.
• As an alternative to the left/right/both selection, the splitter could have a circuit connection point for each side separately. In fact, I like this one much better. It fits with the first point, in using the circuit wire connections to get the behavior we want in a very intuitive way.
• I am assuming that items are directed left or right immediately upon entering the splitter, so that every item in the splitter is already in one of the outputs. If that's not true, then I can't see a way to get accurate counts in all situations.

With the options above, we would have full flexibility to get accurate counts from any belt path that includes the splitter.