Help needed with proximity switches

[TonyD]

Silyavski, I'm having similar issues, maybe my basic explanation will help if my problem can cast a common light on the issues?

I have 2 NPN proximity switches, each a 3 wire switch.

I set up a simple bench test with a 12v PSU and connected proximity switch brown to +ve and proximity blue to -ve then I used a simple continuity tester across the proximity black and brown.
As the proximity senses a metal target, the continuity test works as I would expect.

Then I set up Mach and the inputs so that I can see the BOB inputs are working on the Mach diagnostics screen.

Also the proximity switches light up with thier little LED, they work with a continuity test.

BUT when I connect a -24ve to the proximity switch and the Bob on one pin, and the poximity black to the other Bob pin, nothing happens in Mach.

Any ideas?

[Saracen]

> all black limits together, all black homes together
> i connect 10kohm resistor between the input pin and corresponding wire.

Try adding a separate resistor to each black lead, then linking the free ends of the resistors to the input pin.

Adrian.

[Boyan Silyavski]

> all black limits together, all black homes together
> i connect 10kohm resistor between the input pin and corresponding wire.

Try adding a separate resistor to each black lead, then linking the free ends of the resistors to the input pin.

Adrian.

Tried this to no avail. Sensors will not work this way.

Silyavski, I'm having similar issues, maybe my basic explanation will help if my problem can cast a common light on the issues?

I have 2 NPN proximity switches, each a 3 wire switch.

I set up a simple bench test with a 12v PSU and connected proximity switch brown to +ve and proximity blue to -ve then I used a simple continuity tester across the proximity black and brown.
As the proximity senses a metal target, the continuity test works as I would expect.

Then I set up Mach and the inputs so that I can see the BOB inputs are working on the Mach diagnostics screen.

Also the proximity switches light up with thier little LED, they work with a continuity test.

BUT when I connect a -24ve to the proximity switch and the Bob on one pin, and the poximity black to the other Bob pin, nothing happens in Mach.

Any ideas?

At the end i solved the problem after checking with the board maker. He assured me the diagrams are correct and that only one 10k resistor is needed per input/when 24v/

So i started doubting all else. Measured cabling, connections, all seemed right. Then very frustrated as a last attempt i changed all cabling with new /20AWG/ and it works now.
i believe the under rated /China/ thin cable was playing me tricks. F****g Chinese cables and connections. Never again.


So basically Tony, this is the way to connect them properly / NPN Normaly Open proximity sensors,24V to 5v input./ as described in my first post
The setup with my particular board is the following:
Pull Down inputs on the board and Active Low ticked in green in Mach3/ my board permits to pull up or down the inputs via shorting combination of 3 pins/

Did you check your setup with 2 or 3 sensors directly wired together and directly to the board and 24v, without any connectors and cables in between? + the respective resistors i mean?

This pdf is for my board but it seems everything concerning connecting different types of proximity switches is quite well explained.

[Clive S]

Some sensors have internal pull up resistors built in hence the calculation to determine it. In my case that value was 10K so no external resistor is required.

Your PDF explains that very well. saying R1 + R2 needs to be 10K if R1 (internal) is 10K then R2 (external) is not needed.

Hope this helps. ..Clive

[TonyD]

Thanks Folks.
Silyavski, in the end I didnt need resistors, as Clive says it may be because the Proximity switch has a resitor in it. Like you, I ended up wiring the Proximity sensor much closer to the BOB and it worked! :) I then traced and rewired the connections and the junction box and I'm good now. Just need to mount the proximity switches onto the frame, adjust and then see how I get on with dual homing in Mach. Thanks again.