Will cutting power to Duex5 only cause damage?



  • Hi all, I am hoping to create a sort of emergency stop on a Corexy printer with 3 Z-steppers moving the bed, and all 3 powered from a Duex5 connected to a Duet Wifi. I want to be able to stop the steppers immediately on crashing into the nozzle using microswitches on the z-towers. Cutting AC power to the power supply does work to stop the whole printer, but there is about a 1.5-2 second delay as the power supply ramps down. I'm hoping that interrupting the 24V DC power to the Duex will stop the steppers immediately, but I'm wondering if that will cause damage with the Duet Wifi still running?



  • I don't think it will damage the Duex but because your XY motors will still be active, and the Duet won't know about the power loss to the Z motors, it may try to continue on with XY moves and drag the nozzle over the bed surface.



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  • @fcwilt You can put a switch over one of the yokes.

    @satre You know you can have a Z-endstop and a Z-probe, right? No need to completely kill power.



  • Ah, I didn't know I could also have a Z-endstop as well as a probe. That was one of my questions in another forum that did not get answered, and I forgot about it. Do you have a reference on how to wire that up?



  • I see the socket for Z-endstop on the Duet. What code do I need in config.g to utilize both my probe (Orion Piezo) and the Z-endstop?



  • The Z probe will be used when a G30 command is sent to probe the bed.

    The endstop would be configured in config.g and would be called into use when a homing move is sent using G1 S1 for the Z axis.



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  • Nope. Tried that. However, this does work. Found it in this forum in a somewhat related post:

    M581 Z S1 T0  ; invoke trigger 0 (i.e. M112) when a rising edge is detected on the Z endstop input
    

    You can do this for any endstop, XYZE, so I imagine you could use the E3-E6 endstop inputs on the Duex as well if you wanted.



  • @satre said in Will cutting power to Duex5 only cause damage?:

    M581 Z S1 T0 ; invoke trigger 0 (i.e. M112) when a rising edge is detected on the Z endstop input

    You can do this for any endstop, XYZE, so I imagine you could use the E3-E6 endstop inputs on the Duex as well if you wanted.

    Indeed you can. Suggest you add C0 to that command. Although CO is the default, I always like to explicitly declare these things, just in case something goes amiss with a future firmware update which might inadvertently change the default behaviour. At one time, I had an emergency stop button which would act just like a switch connected to an end stop but which would do an emergency stop any time it was pressed.

    You can also change the "T" parameter to something >1 which will run a macro in which you can put your own commands, rather than simply doing an emergency stop or pause.


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