RRF3 multiple ends tops on Zaxis Min/Max w/ BLTouch for Zmin??



  • Hey everyone, I recently upgraded to RRF3. I have a setup where the Z axis is at ZMin with a BLTouch , but I have a hall effect endstop at ZMax to stop the axis from accidentally topping/bottoming out) when it is at the near end of the axis.

    Before in RRF2 it wasnt easy to use that setup so I left the ZMax endstop unused. With RRF3 I saw there is the capacity to use multiple endstops on one axis. But the instructions on the config for that is not very clear.

    I tried this:

    M574 X1 S1 P"xstop"                                    ; configure active-high endstop for low end on X via pin xstop
    M574 Y2 S1 P"ystop"                                    ; configure active-high endstop for low end on Y via pin ystop
    M574 U2 S1 P"e0stop"                                    ; configure active-high endstop for High end on U via pin e0Endstop
    M574 Z2 S1 P"zstop"                                    ; configure active-high endstop for high end on Z via pin zstop
    M574 Z1 S2                                             ; configure Z-probe endstop for low end on Z
    

    But that didn't seem to work.


  • Moderator

    Multiple endstops on one axis isn't used in the way you're expecting here. It's typically used for leveling an axis that is split between multiple motors. One endstop for each motor, rather than an endstop for min and max ends of travel.

    RRF only supports one endstop for each axis either at min or max. In normal operation the firmware will prevent the axis from moving outside of the set bounds of M208. It's still possible to use the additional endstop though if you wish, both in RRF2 and RRF3.

    First you can use it as an estop switch to stop the printer entirely in cases where skipped steps or misconfiguration has caused the axis to move outside of the software bounds.

    Or second, you can use it as a zmax endstop to home the Z axis in case of a power loss. This has always been possible. You just need a macro that configures the zmax endstop and has the G1 H1 movement commands to move to the endstop.

    In fact, here's an example of using a BLTouch to home to Z min and an endstop for Zmax for power loss, plus a macro to measure the distance of the z axis so that your zmax height is correct.

    https://duet3d.dozuki.com/Guide/Ender+3+Pro+and+Duet+Maestro+Guide+Part+5:+Upgrades/54#s213



  • Thanks for that clarification! When I saw the language for multiple end stops I guess I misunderstood. I'll check that link


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