z probe NPN reprap config question



  • Hi all. Just starting this process so I apologize in advance for what are likely a long list of stupid questions. What type of z probe is an NPN probe in the reprap config setup?


  • Moderator

    I don't understand the question, but here's some info you may not have seen: https://duet3d.dozuki.com/Wiki/Connecting_a_Z_probe#Section_NPN_output_normally_open_inductive_or_capacitive_sensor



  • In reprap config tool it has selection buttons labelled " no z probe, switch, Unmodulated, modulated..etc" it was wondering which an NPN was. Thanks for your help. I am building a fixed bed 1200 x 1500 x 2000 mm Corexy printer with only 3 years of Prusa Mk3s MMU2s experience. It is going to be fun 🙂



  • @Phaedrux Just saw your custom D-bot. Amazing! Similar to mine. I hope you don't mind me picking your mind. My electrical engineering friend and electrical tech teacher have been of little help.


  • Moderator

    @damaged_goods said in z probe NPN reprap config question:

    In reprap config tool it has selection buttons labelled " no z probe, switch, Unmodulated, modulated..etc"

    I think you can use it as a simple switch type. Check your config.g afterwards and see what M558 P type it gives you. I think it should be type 4 or 5.

    If you wire it as shown in the link earlier (to the zprobe signal pin), it should be M558 P5


  • Moderator

    @damaged_goods said in z probe NPN reprap config question:

    I hope you don't mind me picking your mind.

    Not at all.



  • Thank you for the information. My big printer is enclosed, all aluminum construction, has a large 1200 mm x 1500 mm stationary heated (eventually) bed of 9 mm aluminum. The x and Y axis are on a gantry that moves up and down on the z axis. Y has one stepper. X has two and z has two large steppers. X's and Y run on linear rails belt driven. The two Z's are on linear rails screw driven. I have a Duet2 wifi v1.03 clone controller with a 7" touch screen. No expansion boards. I do have a separate Dm860AC microstepper driver. All is powered by a 24 volt ac/dc power source. I don't know what I don't know 🙂 so if you have any suggestions or concerns please let me know.

    My question is about the two x and the two z steppers. Can/should I power/control them through the Duet2 or should I control through the Duet and power through the separate micro stepper driver? The larger Z steppers draw 2.8 A each I think.

    Thanks again,


  • Moderator

    You'll likely be able to power all the motors from the Duet. The Z axis motors should still have enough torque since it's only having to raise the gantry and not the heavy bed and there are two of them. You may want lead screws with a shallower lead to reduce the tendency to fall and reduce the torque needed to lift.

    You can put the X axis on the Z motor connectors which are internally connected in series, and then use the X driver and additional E driver for the second Z motor. Then you can at least do tilt correction for the gantry.

    @damaged_goods said in z probe NPN reprap config question:

    I have a Duet2 wifi v1.03 clone controller

    clone boards may have less copper in them so they may sink less heat, so be sure to have good cooling on both sides of the board.



  • Great suggestions! I will rewire the x's separately and watch the clones cooling. The z screws are finely threaded rod so falling should be easy to prevent.


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