Hi, Admiral Shark here! I must first disclaim that I am not an electrical engineer, but at most a hobbyist. "PE" stands for "protected earth". At least here in the UK, you may see "earth" and "ground" used synonymously (and the former may even by preferred by IEC/BS standards.)
What a ground/earth is doing is quite context dependent. In their documentation, I have seen IBM refer to such pins as either "PE" or "frame ground". I believe PE is specifically intended for a person's safety context, whereas "frame ground" is more signal integrity. But I guess it functionally does both, and IBM didn't standardise how they refer to it? Also, my use of nomenclature was initially borrowed from
KbdBabel. They were my inspiration when I started making these diagrams, because I essentially wanted to fill in the blanks.
This talk gives me an idea, though. Perhaps a new section in my Keyboard Connections page for describing pin functions is in order? As such, if anyone else believes I was wrong and has corrections or has anything else to add to what I said, I welcome it. I only want to put out the best information!
