I’ve built my MPCNC and am starting the long, steep learning curve of carving, printing, and laser etching at the same time. As I read, there are conflicting opinions on a variety of topics including single endstops per axis. Ryan suggests that Beginners really don’t need endstops at all, particularly the dual endstops option, to get started. For wiring of the limit switches if used, he suggests NC (normally closed) for the switches as a safer configuration to avoid accidental tripping and machine damage. Fair enough. The Rambo 1.4 Manual setup suggests either NC or NO with the appropriate firmware edits for Endstop_Inverting set to false or true accordingly, and no preference for which way matters. The Marlin Manual also suggests either way, with the additional option of Endstops_Interrupts_Feature to reduce the number of CPU cycles needed to monitor the endstops (it’s normally commented out). I’ve further read in the Estlcam application that NO is preferred and if there are unexpected endstop trigger events to place a 100nF capacitor between the switch connections. Ironically it seems the simple choice of NO vs NC for an endstop is not as binary as a guy would like it. Is there more to Ryan’s NC preference than meets the eye?
NC, ensures the endstops are working. If a wire breaks the endstop will show triggered and not move.
NO, you wouldn’t know if there was an issue, and it will move and not stop.