Inductive sensor (Z-axis) is not triggering Ramps?

Okay, I have an inductive sensor mounted and wired to my ramps for the z axis (Z_MIN). If I put metal close to the sensor I see the red LED light up on the sensor, so It is getting power and working. The signal pin is connected to the signal (Z_MIN). But when I check the state of my endstops (M119), it only shows open. Both with the red led on or off.

I don't know enough about pull up resistors, Would that help in Marlins? I'm not sure if I already have pull ups on or off currently in the firmware.

And yes, this is a 5v inductive sensor recommended for the build.

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// 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

What Proximity sensor are you using.

It says:

M8 2mm sensing DC 5v Inductive Proximity Sensor NPN NO LJ8A3-2-Z/BX-5V

[www.aliexpress.com]

It was the model recommended.

Thanks

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UPDATE:

I just used a Multimeter and with the sensor regular, it shows +2v on the signal pin. When I trigger it with metal, (LED ON) it goes to zero.

Any thoughts?

(I do believe I have PULLUP resistors turned on in Marlins.

Edited 1 time(s). Last edit at 11/02/2017 03:31AM by disneytoy.

So to verify Black wire connected to Sense, Blue Wire Connect to Ground, Brown wire is the Power.

With a DVM and the sensor NO, it should be +5v on the signal pin. When triggered with metal, (LED ON) it goes to zero.

I'll try 12 volts and see if I get more than 2v on the signal

2mm sensing is very small,this will be much less when sensing alluminium.

carefull, 12volts on the signal wire will kill the processor i/p pin if you dont protect it.

remove the // on this line to enable all pullups

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

I tried wiring the + and ground to 12volt rail.

The signal shows 2.85v

and when the LED is triggered 0 volts.

This is completely off the ramps, just to power and voltmeter.

Any thoughts?

My power supply reads 12.45v on the input.

Edited 1 time(s). Last edit at 11/03/2017 06:49PM by disneytoy.

If you have a 4.7 - 10 k ohm resistor you could wire it between the Black and brown wires to see if an external pull will work.

Edited 1 time(s). Last edit at 11/03/2017 08:30PM by Roberts_Clif.

Thanks Robert,

I was just reading about pull up resistors. I will give it a try.

Edited 1 time(s). Last edit at 11/03/2017 09:23PM by disneytoy.