Does anyone by chance have the pinout for the Totem S’s endstop connectors?
Thanks in advance, that would save me some effort figuring it out on my own.
Thanks, seems the Totem board uses the same pinout on its connectors as a RAMPS board.
Next facepalm is that Marlin wants the endstops to switch between open circuit and 5V, while grbl says to switch between open circuit and GND. Whatever, I’ll just do like an active endstop switch does and switch between 5V and GND…
Interesting that they implemented it that way. Most of the machines I worked on had mechanical limits on them and were wired ‘or’ and pulled the line to ground. Only requires 1 wire with a metal chassis.
Generally you are ‘driving’ something if it needs 5v to switch, leaving a line that is ‘floating’ is bad practice and make fixing something impossible. Most of the inputs of the microprocessors are high impedance and will ‘pick up’ stray noise, if not properly protected. Low impedance are preferred to eliminate noise or false sensing.
Wired or is the most common as virtually all micro controllers and most general purpose cpus can be configure with internal pull up resistors, so all you have to do is pull them down.
“[$5=]This refers to the limit switch pins which by default are set to high using the Arduino’s
internal pull up resistors. Grounding the pin tells GRBL the limit switch is tripped. For the
opposite behavior use the setting $5=1 which tells the system that a high is the limit
switch trigger. You must also install external pull down resistor with the $5=1 setting.”
If you go the high limit switch trigger, you switches are now a wired ‘and’ configuration.
In the end, I suggest you wire it up in the way that makes sense to you, since you get to fix it… 
Indeed ;).
I wired it up yesterday, C to the input pin, NC to 5V and NO to GND. Works well and I’d say it’s more resilient to noise that way—the line is always strongly pulled to one “side”. I think that was the idea behind board manufacturers starting to use the 3-pin ports, too.
And in case anyone finds this thread because they want to do the same:
Send “G10 L2 P1 X-300 Y-300” (300 is the work area size in mm (or actually $130/$131 minus $27)) to the cutter once if your grbl was compiled with defaults (i.e. works in negative coordinates after homing). I wish LightBurn had a config setting to do that trivial coordinate translation itself, would have saved me 2 hours of google-foo.
Pinout is (from left to right, with the red connector on the left): X, gnd, 5V, Y, gnd, 5V.
IMHO, the three pin ports are generally good because you have power, ground and signal, and with many machines today, these limit switches, like mine, need the 12v for sensors.
Great, glad you got it up, take care
Have fun 
P.S. Might want to mark that for the solution if that’s the case …