Connecting two endstops to my Duet Ethernet

  • Hey everyone,

    as part of a project I'm currently converting my Renkforce 2000 to the Duet Ethernet.
    The Renkforce 2000 uses two endstops. One for Z_min (microswitch) and one for Z_max (optical endstop with four pins; light barrier). I've already connected the Z_min endstop to the Duet but how can I connect the Z_max endstop?
    Is it even possible to connect a second z endstop switch? If so, can someone tell how to do it?

    Thanks in advance!

  • Moderator

    Totally possible. I use a z probe as z min, and also have an optical endstop on zmax.

    ; Endstops
    M574 Y2 S0	; Set active-low switch (Makerbot 3-wire) at the high end endstop for Y Max.
    M574 X1 S1	; Set active-high switch (NC Switch) at the low end for X Min.
    M574 Z2 S1	; Set active-high switch (Opto) at the high end for Z Max.
    M574 Z1 S2	; Use zprobe and home to Z Min.

    Then I have a homeZmax.g macro that does just that.

    M574 Z2 S1	 ; Set active-high switch (Opto) at the high end for Z Max.
    G91 ; Relative positioning
    G1 S1 Z330 F300  Move bed down until endstop triggers
    G1 Z-5 F100	; back off 5mm
    G1 S1 Z10 F100	; go back to trigger endstop more slowly

    Just to be safe, I have the endstop redefined at the start of the macro.

  • On the Duets, you get endstop inputs connectors for X, Y, Z, E0 and E1 (thus 5 in total), which can be used and repurposed as needed. So as long as you don't need more than 5, it is simple - for more than 5, you will need a small breakout board (which you can perhaps create yourself if yours needs are simple) that will take the endstop pins from the big connector/header and get it in an easier to use layout (for example breaking out those endstop pins along with a Ground as separate connectors to use).

    Using a probe and Zmax is also a little easier.

    My D5S Mini came with both Zmin and Zmax endstops. Even before upgrading to the Duet I removed the Zmax. The idea is simple: if your slicer is correctly set up, it should not be able to send you any Gcode movements outside of the printer's capabilities. Therefore a Zmax would not be triggered if Zmin is the main Homing endstop. If using a probe which may not always trigger at the same location, you should account for a safety factor. My opinion is that if a print goes to where the Zmax is (or where it needs to trigger to prevent printer damage), then the printed object was too big for the printer - and the print will fail regardless (Z will no longer move).

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