Purpose of non-logic pins

Is the purpose of designating something a “non-logic pin” in the symbol editor to indicate that the pin in question is for power or not connected?

Analog switches, ADCs and DACs,… many other uses.
As @Sprig links above, the ERC check is a rather simple minded sanity check on your circuit.

Actually, the “non-logic pin” designation is only graphical. It is the pin shape (like the clock or negation bubble). Nothing to do with ERC. It is simply for the human designing or reading the schematic.


Is this some sort of convention that I have managed to never know about?

I believe it comes from the “IEEE Logic Symbols” that appeared in the early 1980’s. They use circles and squares and semicircles and several kinds of triangles to indicate things like edge-triggered inputs, 3-state pins, analog signals, etc.

They never really caught on. I think T.I. was the only manufacturer who consistently used them in their literature. You still see the IEEE symbols from time to time, but they are definitely the exception rather than the customary practice. And, unlike the rectangle-versus-jagged-line alternatives for resistors, most times when I see an IEEE logic symbol I have to get a cheat sheet to decode all the graphic shapes.



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