Hello!
Is it possible to add outgoing virtual signals that will inform about the state of the teleport, for example:
- Signal "E": from the word "empty", equals 1 if the teleport is empty;
- Signal "F": from the word "full", equals 1 if the teleport is full;
- Signal "S": from the word "slot", displays the number of empty slots left in the teleport;
- Signal "Info": displays the total number of slots available for the teleport.

This will help a little in more precise control and automation of the teleportation process.

You can already do a lot of this with the current signals, since you can read the teleporter's contents and whether it is working, but of course the circuits will be more complicated. So some of this could be useful. I'll give some more thought about how I might implement it.

Hmm... I could only read the contents of the teleporter and could not receive any other signals.
Maybe I'm doing something wrong? Could you send a screenshot of how to properly connect the teleporter to the network to receive more signals?

Regarding signals - suddenly this mod can be useful, that's where I took examples of signals from.

https://mods.factorio.com/mod/osha_container_signals

A teleporter is just a container, so you could probably just use that mod if you want its functionality.

Anyway, you can only read the contents of the teleporter, but the contents are all you really need.

For example, here's a blueprint of a circuit that sends an "E" signal if the teleporter is empty.

0eNqFkt1qwzAMhV9l6NoppEtCY9jV6FOUEvKjtmKJHWylayh+98lpWcc26KWOpE9Hsq/Q9BOOjgyDvgK11njQuyt4Opq6j5qpBwQNvrgkvT2SZ2oTxh5H6xgdBAVkOryATsNeARomJrxBlmCuzDQ0UqlT9QymYLRe+q2Jk4WZZOVmlSuYQRfpKg9B/aGuv6kdttShS1o7NGRqtv8D77hXwSnoyGF7y2cKZH12tq8aPNVnkn5pulMryXULyUf1ZySbHsh5rh5H43mMjs7keBLlsfhSkeAZ3cwnMsd4P/E71m7xq+EN4hntxOPEv5/iCXV7g42zeJ0MVwdnh4qMgEAf6t5j2IcQ6Z+ydGTvUpWqtUr3ohHjIKjHd1DQ1w3KXNgOI88v7ydsP0QV6365V16sy6ws8zxPN1mRhfAFzfPIpw==

This one sends an "F" signal if the teleporter is full, which is a little more complicated. (Even more so if you want to account for quality, which this doesn't)

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

I'm sure more can be done with these kinds of circuits but these are some simple examples that I hope are helpful.

Definitely useful :)
Well, if you can implement signals from the teleport itself, then it will be easier of course :) No matter how you look at it, but having just one combinator that reads signals better than several.
Thanks for the examples.