U axis endstop doesn't exist? It's in my config.g

[terbospaghetti]

Hi everyone,

This one has me stumped, I have no idea what to even try.

I'm building an IDEX machine with endstops on either side of the X axis linear rail.

Fully updated MB6HC and EXP3HC and NC microswitches if it matters.

My problem is that no U axis endstop is present when I check with m119, despite having the following in my config.g:

; Endstops
M574 X1 S1 P"io1.in" ; configure active-high endstop for low end on X via pin io1.in
M574 U1 S2 P"io4.in" ; ADDED U AXIS ENDSTOP AT HIGH END
M574 Y1 S1 P"io2.in" ; configure active-high endstop for low end on Y via pin io2.in

I can't figure out what I did wrong to get the board not to even believe it exists.

My wiring is correct, identical to the X axis endstop which works fine.

Here's the response to m119 if anyone wanted to see.

HELP PLEASE!

[terbospaghetti]

A new clue!

When I restart the board I receive this error:

"M574: Invalid use of P parameter"

That one is a real confuser. Is my selected pin not ok for endstops?

[Phaedrux]

Post your full config.g so we can see what is happening please.