NPN NO proximity sensor as homing

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JohanC
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Joined: Sun Jan 22, 2017 8:39 pm

NPN NO proximity sensor as homing

Post by JohanC » Sun Jan 22, 2017 9:00 pm

Hi.

In my CNC project I have to use a sensor that is not touching the actual thing its homing agains so I want to use a proximity sensor.
But I am having a hard time setting it up. As i understand the Arduino has an internal pull up which set the homing pins to +5 and to trigger it i have to connect it to ground? So how do i manage that with a proximity sensor? As i understand a npn no sensor gives for example +12v on the out pin if i connect the + pin to +12v and - to ground. And when the sensor is on the out pin goes to 0v which would trigger the home pin on the arduino? But wouldn't the +12v damage the Arduino? And even if i put a resistor to pull it down to 5v, wouldn't the Arduino get damaged by having it set to +5v internal and then get 5v from the sensor when not activated?

Regards, Johan

Bertus Kruger
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Re: NPN NO proximity sensor as homing

Post by Bertus Kruger » Mon Jan 23, 2017 7:58 am

NO switch is connected to an end-stop pin and ground. when the switch is triggered it pulls the pin to ground and it triggers the software.

12V will damage your Arduino....

you could use an infrared led sensor that returns 5v if its not triggered and 0v when the beam gets triggered.

JohanC
Posts: 3
Joined: Sun Jan 22, 2017 8:39 pm

Re: NPN NO proximity sensor as homing

Post by JohanC » Mon Jan 23, 2017 11:22 am

Okey, so:
Brown cable to +12v power supply
Blue cable to ground on power supply and to ground on the cnc shield
And then some sort of voltage divider on the black cable and then to end-stop pin? Any suggestions on a good voltage divider solution?

ford460ho
Posts: 8
Joined: Sat May 06, 2017 5:01 pm
Location: Utah

Re: NPN NO proximity sensor as homing

Post by ford460ho » Mon Dec 03, 2018 9:07 pm

I dont know if this is to late but I found this useful.

https://youtu.be/F7BjZElStfQ
Jack of all trades, master of none.

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