The most basic type of switch is a lever arm, micro limit
https://www.amazon.com/HiLetgo-V-156-1C ... 467011_1_7. Most of these come with 3 wire points labeled NO [normally open], NC [normally closed], and COM [common]. Run a wire from the COM post to one of the ground terminals on your DB25 breakout board [pins 7,19, or 25]. Run another wire from either the NO or NC post to the correct axis terminal and designate the setting on the control screen.
For example; Motor 0 is your X axis, and it homes to the minimum travel location. The switch is wired from COM to pin 7 and NO to pin 3 on the breakout board. On the buildbotics control screen under
Motor 0 in the limits section,
min-soft-limit is set to 0,
max-soft-limit is set to your specific travel extent,
min-switch is set to normally open, and
max-switch to disabled.
Doug from buildbotics also has a link to some magnetic proximity sensors that he uses in a post in the FAQ section of this forum.
Currently I'm using Xtension limit switch kits from OpenBuilds
https://openbuildspartstore.com/xtensio ... witch-kit/. These are labeled GND, V+, SIG. My X switch is wired GND to pin 7 and SIG to pin 3 [the V+ wire isn't needed here].
There is other info in the "Docs" section at buildbotics.com [url]
https://buildbotics.com/docs/[/url ]if you want to use a 5v proximity sensor.
I hope this helps you some.
MC