Using 10-30V Proximity Sensors

[Nightowl]

I'm replacing the limit switches with proximity sensors on my CNC machine and, although there is evidence to show they work with 5V, I was wondering if it would/could be better to use a 12V supply.

I was thinking of taking 12V and GND from the two-pin header adjacent to the 5V PWM header, but getting the signals from the I/O headers. Obviously the GND would need to be a common ground between the headers?

Having said that, in the not too distant future I'm hoping to add a milling motor and use these and the PWM header for that, so maybe it's not a good idea..?

Thanks

[dc42]

@nightowl999 you can interface NPN-output proximity sensors directly with the IO input pins of most Duets. The sensors can be powered with up to 30V. PNP output sensors can't be connected directly.

[Nightowl]

@dc42 Oh, right. So it would be a direct replacement, but should I use the 5V pin rather than the 3.3V, or doesn't that matter, either?

Mine are NPNs.

Thanks

[dc42]

@nightowl999 you should connect to neither the 5V pin nor the 3.3V pin if you want to power the sensor from 12V or 24V.

[Nightowl]

@dc42 So, if they don't work effectively with 5V, are you saying my original suggestion of connecting the supply +ve to a 12V option would work and that the GNDs are common throughout the board?

Thanks

[dc42]

@nightowl999 yes.

[Nightowl]

Thank you, @dc42