I would like to have a nice way to differentiate the following situations:

• The ghost scanner has not been placed yet (Possible by wiring a constant combinator set to signal-0=1 to the ghost scanner and then wiring the ghost scanner to what i want to use. It will only send exactly the constant combinator signal, if the ghost scanner has been build and detects no ghosts.) A more direct way would be having the ghost scanner (optionally) send a signal, if it is placed.

• The ghost scanner is placed, but not connected to a logistic network. (You could wire in a roboport, but that is neither the fine british way).

• If it happens(untested, i think it can happen based on the source code): The ghost scanner has been built, but has not yet scanned for ghosts.

A way to reach this would be to have some virtual check signals showing (a) if the scanner has already scanned and (b) if the scanner is connected to a logistics network. To not break working systems, these options could be added in the settings.

No other combinator sends an "I am here" signal. Why should ghost scanner?

And a signal saying, I am not connected to a logistic network? This would not really break the idea of factorio. Every logistic chest tells you, if it is not connected to a logistic network.

For the last point, one fix would be to scan as soon as a combinator is placed. As far as I can tell, this does not happen.

I could add a signal counting the number of cells/roboports in the network.

It doesn't matter if ghosts are scanned few ticks sooner or later.

It does if you are trying to send a signal as soon as construction has finished. Especially if that signal is intended to be recieved by part of the structure which may or may not have been build yet.

But if the combinator checks for the number of cells in the network when it updates, that solves all my issues.

There is also the work around of having the ghost combinator with a signal in the blueprint. The set signal vanishes as soon as ghost scanner is updated for the first time.