New Build, Aluminium Frame Router/Mill

**JAZZCNC** · 12-03-2016

The manual shows PNP swithces and your using NPN. Take 12V to pin 10 and Put Black wire to Gnd. Then it will work.

**Davek0974** · 12-03-2016

Originally Posted by JAZZCNC

The manual shows PNP swithces and your using NPN. Take 12V to pin 10 and Put Black wire to Gnd. Then it will work.

This is the manual i used http://cnc4you.co.uk/resources/CP0-10V.pdf, the switches and sensors pull the pins down to activate, I guess thats active low, and i thought NPN was sink or active low output i.e the pin is pulled high internally and the sensor pulls it low?

**Davek0974** · 13-03-2016

Sorted

These switches cannot be used for combined homing/limits - the flickering output immediately triggers a limit fault after homing as it sees the flicker as the next sense input. Probably just crap sensors.

My fix was to use them for homing only, then add soft limits to control the position limits on all axes - the mill will always be homed when in use so this seems a safe option.

However, as the sensors all use one input, it sees the flickering as the next axis sense and just zeros all the dro's - did i say these sensors are crap?

The fix - modify the home-all button script to something like this for all axes...

DoButton( 24 )
While IsMoving()
Wend
DoOEMButton(133)
While IsMoving()
Wend
Code "G53 G1 z-3 F500"
While IsMoving()
Wend

This runs the home, zero's the DRO, then steps back 3mm which is enough to get the target clear of the sensors, then it moves onto the next axis and so on. It works perfectly but does leave the tool at X3, Y3, Z-3 but then you can jog back if it matters as the soft limits will stop a crash. It does NOT work without the While IsMoving lines in there. Debounce does NOT make any difference and is now set to zero.

I guess I could add a move to zero on all axes after the homing finishes, just to park it all at zero.

A video of homing working nicely...
https://youtu.be/T2CeluqhRl4

Now i can start final wiring and finish the build, damn good fun playing with it though

**Clive S** · 13-03-2016

These switches cannot be used for combined homing/limits

I don't think it is right to condemn the switches and say they don't work for combined use. Lots of people use them it all depends how they are wired. NPN and PNP are different and have to be wired different.

**JAZZCNC** · 13-03-2016

Dave these switches 100% do work for both I use them all the time. It's either your using them wrong or possible the BOB doesn't work like you think.?

How you have worked around the problem may well work but I wouldn't trust for repeatabilty.

I think the answer to the problem is you'll need to use 10k resistor to force the input high.

**Davek0974** · 13-03-2016

ok, but the inputs are already pulled high internally by 4k7 so surely another pull-up would be bad??

You can see the LED on the sensor flickering unless the tip is 100% covered by the target, this does not match my previous experience of inductive sensors where they are either on or off - NO flickering!

This is not a PNP/NPN issue, these are NPN and wired for NPN normally open.

JAZZ, you use sensors, does the LED flicker?

here's a video...
https://youtu.be/S5PP5sQh5Vk

**JAZZCNC** · 13-03-2016

Even the super cheap Ebay ones work ok dave.

You haven't wired the switch powers in series have you.? That flickering looks like struggling for volts.!

**Davek0974** · 13-03-2016

Originally Posted by Clive S

I don't think it is right to condemn the switches and say they don't work for combined use. Lots of people use them it all depends how they are wired. NPN and PNP are different and have to be wired different.

I didn't mean "these" as in all sensors, just maybe these super cheap eBay ones possibly, they were only £2.50ea. Previous experience was that the LED & output was either ON or OFF, not flickering depending on how close the target is.

**Clive S** · 13-03-2016

Originally Posted by Davek0974

I didn't mean "these" as in all sensors, just maybe these super cheap eBay ones possibly, they were only £2.50ea. Previous experience was that the LED & output was either ON or OFF, not flickering depending on how close the target is.

You got robbed you can buy them for about £1.30 on ebay. I think you might be correct with the pull ups in that case I think you will need PNP sensors. But that doesn't mean they are crap.