Bed Temp Spike

  • Hi All,

    Very occasionally (seen one in a 1hr10 test run, but may have missed some - like as I'm typing now!) I'm seeing the web control report a instantaneous temperature spike on the bed temperature when I have nothing connected to the bed temperature input. The spike is to the top of the display chart which is 250°C.

    I've currently got a core x-y build under test with no heat, and only the hot end thermistor attached. I'm running a build file with no heat but all three axis moving.

    Current Spec:

    Duet 0.6 Running DC42's 1.19.1rc4
    External 5VDC 3A PSU - Siemens LOGO!Power (DIN mountable, found in stores!)
    24VDC 14.6A PSU - Ooznest supplied Weho
    Currently no earth bonding, it's on the to-do list.
    Ooznest stepper cables are not shielded, there is no shielding around the stepper motor plugs like on the Ormerod 2.
    No heaters connected.
    Z axis steppers running in series.
    E3D Titan extruder (moving, no filament!) with V6 hot end & 0.9 degree stepper.

    Is this a known thing? I'm going to be setting up a relay to kill the power to the 24VDC supply in the event of a heater fault and I'm concerned I will need to fix this to stop it dropping out on false trips. Generally with the sensor unconnected it reports -3.0°C ish. I was hoping to avoid the need for extensive shielding and tackle it at a later date when time is more plentiful! 😉 Earth bonding, including the stepper bodies is high on the agenda though.


    Y/Y/Z#1/Z#2 - JK42HS34-1334A
    Extruder Motech Motor MT-1701HSM140AE 0.9° /STEP 170318

  • Just had three more in close succession.

    Edit: Are there loggers I can trigger to 100% confirm this is something happening on the printer rather than a bug on the Web Control?

  • Since seen the Spurious heater faults thread, and the wiki article. I've also seen that the M570 command says the default for a heater fault is 5 seconds, so the fault shouldn't case me a problem. I'd still like to look into it more is any one has had experience with this that they can offer.

    Upgraded firmware to 1.19+5 now. I've been running for 32 minutes and not spotted any spikes yet, but the notes on rc5 didn't indicate any changes on temperature side of things so think this may be a fluke.

  • administrators

    Probably a fluke. We had a user who's bed readings went weird whenever the microwave was in use…. interference issues can be a pain to track down. Assuming it's a standard corexy I assume your bed is static and the spikes are.not related to the bed being in a certain position

  • I'll keep an eye on it then. Guess the first points of action are better earth bonding anyway - so I'll get on with it!

    Way to keep an eye on it in the standard releases without having to watch the Web Monitor for complete builds?

  • administrators

    I don't think spikes that don't trigger a fault are reported in M122 or debug output.

  • Fair enough. Sounds like a simple python program to mimic the temperature plotting bit of the web sever would be the way forward, and hope the update frequency catches the spike if present. I'll keep this in mind and put it on the 'to tackle later' shelf unless it becomes more critical.


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