Testing Power Fail and Resuming Print Issue



  • Hello,

    I'm working to get the resume after power failure feature running, and I keep running into the same issue that I can't seem find another topic on.

    I'm working with a Core XY printer newly converted to a Duet Wifi, that seems to be running great with firmware 2.01. I'm working to implement some of the cool features on the Duet like the power fail protection.

    With that, my current resurrect-prologue.g is the following:

    M116
    G28 XY
    G30 H0.45
    M83
    G1 E5 F600

    I normally home in the bed center so I added the G30 to home Z. I noticed there is a decent probe trigger height difference at (0,0) so currently I have a compensation of .45mm on the Z.

    When simulating a power failure, the resurrect.g file is created as expected. When restarting and issuing the M916 command everything goes well until the homing routine. The problem seems to be that when the G30 command is executed I keep receiving the same message: "Error: Z probe was not triggered during probing move. Error: Homing failed." X and Y home correctly but the bed moves up to attempt to home z, but after a cm or so of travel the error is returned with no Z homing. The print then resumes as the right X,Y location but the Z is always incorrect because the homing never occurred.

    I've been able to get one good resume when I did the power fail pretty early on, within the first 10mm of the print. It seems like there's a limit to how far the bed will travel when attempting to home z when running the resurrect-prologue.g file. When the print is too far along I cam't seem to get z to home properly.

    Thanks for any help with this.

    Huw


  • administrators

    What type of Z probe are you using?



  • i didn't think you would home Z when there is a power loss... you would just run into the print unless you did home to max. setting it to ignore the un-homed z might work so you just home X/Y and Z stays as is.



  • It's an inductive probe.

    I just noticed I might have my y offset reversed on the G31 line in my config.g . If the probe in located in front of the nozzle is this a positive y value in G31?



  • @mrwizzard I've wondered about that. Reading through the guides and whatnot it looks like you can lose a handful of step if you don't home Z, but based on my testing that would probably be accurate enough to not affect much on printing. I don't know if can rely on the M911 Z movement command to be accurate enough to then remove this the movement when restarting. Do you know what the resurrect-prologue.g would look like for this type of resuming without homing Z?



  • Interestingly I found that if I manually perform the X home, Y home, and the G30 H0.5 command, I was able to get a successful restart. I changed my resurrect-prologue .g to separate the X home, Y home, and Z home to copy what I did exactly and so far this seems to be working.

    resurrect-prologue .g:
    M116
    G28 X
    G28 Y
    G30 H0.5
    M83
    G1 E5 F600


  • administrators

    @hmolineux said in Testing Power Fail and Resuming Print Issue:

    It's an inductive probe.

    I just noticed I might have my y offset reversed on the G31 line in my config.g . If the probe in located in front of the nozzle is this a positive y value in G31?

    1. Are you sure that your inductive probe isn't triggering spuriously, perhaps because when you probe at the edge of the bed it is close to an extrusion or some other metalwork?

    2. Usually, printers are set up so that +Y movement moves the print head away from you or the bed towards you. If your printer is set up that way, then if the probe is in front of the nozzle (closer to you than the nozzle), it has a negative Y offset.


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