oh no, the article mentioned about setting up the endstops with m574, I've read several times ... and yet not correctly implemented ... 😣
the solution of the problem:
M574 Z2 U2 X1 Y1 S1
; for my documentation
; Xn / Yn / Zn / Un -> endstop position
; ... n = 0 -> no endstop
; ... n = 1 -> at low end (min endstop)
; ... n = 2 -> at high end (max endstop)
; Sn -> endstop type
; ... n = 1 -> active high (NC), default
; ... n = 0 -> active low-high (NO)
Thanks for your help 👍