Water meter / Problem with inductive proximity capacity switch

[cvdk]

Hello,

I am calling to your expertise for my problem because I do not understand at all what is wrong.

I mounted a inductive proximity capacity switch LJ12A3-4-Z/BX 6-36V on my water meter.

I connected the brown wire to +24V, the blue wire to the GND and the black wire to a loxone digital input of my miniserver. When I take water in my house, the red led of the sensor flash at each liter of water but I have continuously +24V at the digital input (black wire).

I tried to invert the wires and i connected the blue to my DI and the black to the GND. In this configuration, the DI remains at +0V continuously and the red led is always at 20% of intensity and flash at 100% at each liter.

I dont understand what is wrong in my wiring/mounting. Do you have any idea ? Do I need to consider that the sensor is defect ?

Many thanks in advance for your help.

[cvdk]

Maybe, I will use  LJ12A3-4-Z/BY instead of   LJ12A3-4-Z/BX ?

[Duncan]

the sensor you are using is a pnp open output inductive sensor so it only detects metals (there is no capacity in this)

your original wiring was correct - brown 24v, blue 0v and black is the signal

https://automation-insights.blog/2018/02/14/an-easy-way-to-remember-pnp-and-npn-sensor-wiring/

as its pnp, it should work without a pulldown resistor

it may be faulty

it only has a sensor range of 4mm - how are you connecting this to your meter to detect what? and at what frequency are you expecting pulses?

[cvdk]

OK. I think that's the problem: the sensor I used is a NPN and not a PNP.

I made a montage similar to this photo.

The metalic target of my meter is well detected (red light flash when it is aligned). Only the signal remains at +24V in my DI.

I will order the same in PNP version. 

[Duncan]

you can use the npn version, but you will need a pullup resistor from the output to 24v and the output will be inverted but you can correct this in your config easily