Inductive sensor issues

I am attempting to wire my LJ18A3-8-Z/BX inductive sensor; an NPN NO sensor. I have tried the suggetions from every video (such as the one from RCJOSE and web page I could find but I think I must be missing something, or my sensor is faulty.

The sensor's LED lights when proximity is sensed, however, the voltage itself does not drop. With, for example, 12v dc across the Brown/Blue wires the voltage across the black/brown wires simply stays at 12v when proximity is indicated. It actually drops by like .1v (from say 12.2 to 12.1) but definitely not usefully. Any ideas?


Michael

I have come to the conclusion that the sensor is bad. I have a new one one order.

Michael, sorry I missed your first post. I had some issues with my own inductive sensor too. I discussed what I found here post

Smerrett79, so you just connected the black signal wire to ground, blue ground wire to the ramps signal pin directly, and the brown wire to 12v? Is that correct? I just got a NPN proximity sensor, so I want to get it right.

Thanks

Mike

Using the NO (Normally Open) NPN sensor I have Wired Normally

Brown - 12v
Blue - Ground
Black - Signal

I get 11.5v No LED without metal near sensor. Bright LED and 0v with metal near sensor.

Wiring it your way.

Brown - 12v
Black - Ground
Blue - Signal

I get Dim LED 2.84v without metal near sensor. Bright LED and 0v with metal near sensor.

Wired your way, I connected the blue directly to RAMPS Zmin Signal as you said to, and it worked.

I made sure ZMin Endstop Inverting was set as true like below.
const bool Z_MIN_ENDSTOP_INVERTING = true;



Thanks

Mike

Edited 5 time(s). Last edit at 09/12/2015 10:06AM by madmike8.

The inductive sensor I bought to replace my aliexpress dud (https://www.amazon.com/gp/product/B008FZC8F2/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1) is working well. I got lucky and it senses and triggers with 5vcc. My bed is aluminum foil backed 2.5mm glass and it picks it up and triggers it at more than a cm from the glass surface.

Edited 1 time(s). Last edit at 09/15/2015 08:40AM by MichaelBrock.