Induktive Endstops

schpongo

I would like to use these as end stops because i I had access to them.
http://www.alliedelec.com/m/d/c61f20ff7bb9a41df9bd3bd6cbfa7ae7.pdf

But i'm not sure how to wire them.
I don't suppose I can simply connect the sensor to the 24V of the duet and then run the Signal wire of the sensor to the output wire of the end stop, as I would be feeding 24V into the signal pin.

Please correct me if I'm wrong, but don't I need to use a voltage divider to get to 3,3V or use another transistor to to switch the 3,3V of the duet with the output of the sensor to the signal pin of the duet.

Thanks for the help
Daniel

TLAS

I use inductive sensors on my build - I remember DC42 recommending a transistor or something while using them, although I don't on mine. I connect brown to 24v, black to the ground and blue to the sensor pin. Off of memory here though, could be wrong.

dc42

Those sensors have a PNP output, which makes it difficult (NPN output sensors would just need a diode). You need to sink a little over 1mA of current from each endstop input, so a voltage divider isn't really suitable. I suggest you use a small signal NPN transistor and a couple of resistors, like this:

47K resistor from sensor output to transistor base
4.7K resistor from transistor base to ground (ground pin on endstop connector)
Transistor emitter to ground (ground pin on endstop connector)
Transistor collector to endstop STP pin

This will give a low signal when triggered, so use parameter S0 in your M574 command.

The sensors that TLAS is using must be NPN-output sensors.

schpongo

Thanks for the quick reply.
Worked like a charm.

Would have posted a picture but i don't think that is possible/

T3P3Tony

You can post an image up uploading it to postimg or similar the using the img tags to include it.