530,147 active members*
2,727 visitors online*
Register for free
Login
IndustryArena Forum > Machine Controllers Software and Solutions > PlanetCNC > using NPN inductive sensors for Limit
Results 1 to 7 of 7
  1. #1

    using NPN inductive sensors for Limit

    Hello everyone,
    I'm in the process of converting my CNC Router from Estlcam to Planet CNC.
    Esltcam Required NPN Inductive sensors as limit switches. Therefore I have tose installed on the Router at the moment.

    When triggered they are creating a connection between Ground and Input.
    From my understanding the "Adapter for limit switch and input switch connection of Mk3 controller" only works with PNP sensors as it requires switching V+

    Are there any objections to connecting NPN Sensors directly to the MK3 Board?

  2. #2
    Moderator
    Join Date
    Mar 2017
    Posts
    698

    Re: using NPN inductive sensors for Limit

    I suppose you could do this in theory.
    But I always use optocouplers in limit switches. Those long cables all over machine can be real trouble.

  3. #3

    Re: using NPN inductive sensors for Limit

    Well Optocouplers on NPN does not really work from my understanding, they all require PNP as they all switch on voltage and not on ground on the input side.

    I think I will give it a try. I have shielded cables and it worked fine with the estlcam controller.

  4. #4
    Moderator
    Join Date
    Mar 2017
    Posts
    698

    Re: using NPN inductive sensors for Limit

    Input and limit pins are internally pulled-up to 5V.
    Be careful not to damage them with indicative switch higher voltage.
    Anything higher that 5V on pins will damage them beyond repair.

  5. #5

    Re: using NPN inductive sensors for Limit

    will keep it in mind

  6. #6

    Re: using NPN inductive sensors for Limit

    quick update:
    I checked the sensors I have installed on my CNC and even though being NPN they seem to have some V+ parasite power on the Out Contact if they are not triggered (the once I used on the bench did not show this behavior)
    They somewhat work connected to a optocoupler but they tend to trigger spontaneously and unpredictably during rapid moves causing Estops if the estop flag is set in the configuration.
    As I have some PNP sensors on the shelf I will switch to those, it will require some relabeling but better safe than sorry.

    BTW: is there some way to see what event triggered the estop? I had some trouble pinning it down to the inductive sensors as it first looked es if it was caused by the error pin from my stepper motors. Having a message in the output windows telling which port triggered the estop would have been very helpful.

    Best Regards
    Klaus

  7. #7
    Moderator
    Join Date
    Mar 2017
    Posts
    698

    Re: using NPN inductive sensors for Limit

    I'll consider this idea.

Similar Threads

  1. Connecting PNP inductive proximity sensors to BOB
    By DanielRe in forum General CNC Machine Related Electronics
    Replies: 1
    Last Post: 10-22-2014, 07:37 PM
  2. Replies: 23
    Last Post: 04-13-2013, 12:30 PM
  3. Using inductive sensors with Mach3 & C11
    By George in forum General CNC Machine Related Electronics
    Replies: 14
    Last Post: 05-05-2009, 11:49 PM
  4. Inductive Proximity Sensors
    By nickfox in forum General CNC Machine Related Electronics
    Replies: 3
    Last Post: 09-07-2006, 03:15 AM
  5. Inductive Proximity Sensors-what are they?
    By Splint in forum General CNC Machine Related Electronics
    Replies: 3
    Last Post: 08-01-2004, 11:24 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •