NPN Inductive Proximity Sensor

Good Evening,

Printer: Prusa i3 + Ramps 1.4
Configuration File: [pastebin.com]
Voltage Divider Wiring: [dl.dropboxusercontent.com]
Sensor: [www.amazon.com]

I am at kind of a lost right now... I pruchased a LJ12A3-4-Z/AX 4mm NPN Proximity Sensor, and I can't seem to get it to trigger issuing a M119 command.

I have wired a voltage divider with 2x10kohm resistors, and I have checked the voltage output which gives me 5v. Currently I have it setup where it is supplying the sensor with 12v, Wired the Output wire to signal, and the ground wire to GRD on the ramps 1.4 board end-stop, leaving the only open pin vcc on the endstop zmin pin-out. I know the sensor works because when i put it up to metal the LED on the sensor dims and the output voltage changes from 0v->5v. Also I know the port on my ramps 1.4 works because I can put back my mechanical switch and it OPEN-TRIGGERED with the m119 command. Anyone have any ideas on what could be the problem?

Edited:
I have checked the output for the endstop pinouts on the ramps 1.4 board and it is still supplying 5v from Signal-Ground. I thought disabling the ZMIN_PULLUPS in the firmware would stop the 5v from going through the Signal pin?? If so why would it still be supplying 5v over the pin?

Thanks

Edited 1 time(s). Last edit at 12/11/2014 11:59PM by coldfront.

That sensor is a NC NPN sensor. It works by always grounding the signal wire until it's tripped, in which case the circuit opens and the signal wire should be pulled high by a pull up resistor. It should be wired and configured just like a NC mechanical switch with the addition of the extra wire to power the sensor, so you should enable the pull up resistor in the config file and ditch the voltage divider resistors. That sensor is a 12V sensor so you won't be able to use the 3rd pin on the endstop connectors on the ramps board. Those are only 5v. You'll need to steal the power from the 12V aux connector by D2 (better for fused protection) or from the power supply (unfused).

Quote
cdru
That sensor is a NC NPN sensor. It works by always grounding the signal wire until it's tripped, in which case the circuit opens and the signal wire should be pulled high by a pull up resistor. It should be wired and configured just like a NC mechanical switch with the addition of the extra wire to power the sensor, so you should enable the pull up resistor in the config file and ditch the voltage divider resistors. That sensor is a 12V sensor so you won't be able to use the 3rd pin on the endstop connectors on the ramps board. Those are only 5v. You'll need to steal the power from the 12V aux connector by D2 (better for fused protection) or from the power supply (unfused).

Thanks for the reply... i feel kind of stupid right now I solved the issue last night... I had the wire plugged into the VCC which is why there was a loop of 5v. I am glad I did not fry anything and it is working perfect right now.

Hi. I know it is an old post but could share the wiring you are using ? I am having trouble to setup my LJ12A3-4-Z/BX with my Ramps 1.4

Thx

Never mind my wiring was ok but I had some defect in the cables junctions.