What settings in Marlin makes inductive sensor trigger correctly?

For the life of me I can't seem to figure out the Z-Min Endstop for a Inductive Sensor. I have LJ18A3-8-z/8X Inductive Sensor and it works. I have it wired right and the blue wire is in the Z-Min Pin on my Ramps board. It senses everything fine as the light lights up when near the the bed and all that, but in Marlin It does not change its trigger when I use M119. Nor does it stop the Z-Axis from moving.

My settings are listed is below. Am I missing something? It there more settings than just this that needs to be changed?
Both inverting it from True to False doesn't seem to help.


Any help would be appreciated.

//===========================================================================
//============================== Endstop Settings ===========================
//===========================================================================

// @section homing

// Specify here all the endstop connectors that are connected to any endstop or probe.
// Almost all printers will be using one per axis. Probes will use one or more of the
// extra connectors. Leave undefined any used for non-endstop and non-probe purposes.
#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG
//#define USE_XMAX_PLUG
//#define USE_YMAX_PLUG
//#define USE_ZMAX_PLUG

// coarse Endstop Settings
//#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors

#if DISABLED(ENDSTOPPULLUPS)
// fine endstop settings: Individual pullups. will be ignored if ENDSTOPPULLUPS is defined
//#define ENDSTOPPULLUP_XMAX
//#define ENDSTOPPULLUP_YMAX
//#define ENDSTOPPULLUP_ZMAX
//#define ENDSTOPPULLUP_XMIN
//#define ENDSTOPPULLUP_YMIN
//#define ENDSTOPPULLUP_ZMIN
//#define ENDSTOPPULLUP_ZMIN_PROBE
#endif

// Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
#define X_MIN_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MIN_ENDSTOP_INVERTING true // set to true to invert the logic of the endstop.
#define X_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Y_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MAX_ENDSTOP_INVERTING false // set to true to invert the logic of the endstop.
#define Z_MIN_PROBE_ENDSTOP_INVERTING true // set to true to invert the logic of the probe.

Blue wire is not the signal wire.

If you have connected the brown wire to 12 volt, you may have damaged the endstop port on the mega.

Your probe is showing as a NPN NO type so the best way to connect it is as follows

NPN probe

Any diode should be ok, i use a 1N4148 type

Hmm by what you said I may just have to rotate the plug on the pin. I'll try that when I get home. When I first wired it up & soldered the transistors on I went by what the sensor had listed on the side of it. That was a few months ago. I'm just now getting to hooking it all up. I'll double check it all when I get home.
Hopefully I didn't damage the endstop pin.

Seems my cell phone double posted. So I'll just edit this as my next reply.


Well I did have the blue and black wires swapped. I switch them and now I can get the M119 Command to show the Z Endstop triggering when I put metal up to the sensor... BUT ... It still is not stopping the Z Axis from moving.

My X and Y Endstop's seem to work. They stop the Axis from moving. Its just this Z Endstop. It won't stop my Z Axis.

Setting up my Delta printer was so much easier than this. LOL

Edited 1 time(s). Last edit at 09/23/2017 11:10PM by VectorRoll.

The only thing different about inductive sensors in the setup in Configuration.h is the Z_PROBE_OFFSET_FROM_EXTRUDER is positive. Other than that.... everything is the same.

I just tested the Inductive Sensor on the Z- Max Endstop Pin and it works for it stopping the motor. Maybe I burned something out that is keeping it from sending a signal from the Z-Min Endstop pin.

Is there a way I can use the Z-Max endstop pin as for the Z-Min?

Never mind on last question. I figured out how to change the Pin. I opened up the Ramps.h file and switched the Z-Min pin from 18 to 19 and vise verse for the Z-Max pin. Now my inductive sensor works stopping the motor.

Guess I did burn something out on that Z-Min Pin. Oh well. At least I got it working now.