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    Noisy/Fluctuating temperatures in idle since updating to RRF 3

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    • MegaAndyundefined
      MegaAndy @Phaedrux
      last edited by

      @Phaedrux oh, didn't think the config override would change any settings if currently empty anyway. I will remove the m501 as my next test.

      That said, I can see the issue of temperature fluctuating when the printer is idling which I would have thought means the PID tuning is irrelevant for this in particular.

      Phaedruxundefined 1 Reply Last reply Reply Quote 0
      • Vetiundefined
        Veti
        last edited by

        @MegaAndy said in Noisy/Fluctuating temperatures in idle since updating to RRF 3:

        M307 H1 R2.520 C195.7 D4.99 S1.00 V13.2 B0

        that means you tuned without the fan

        use M303 T0 S200 to tune the new algorythm

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        • Phaedruxundefined
          Phaedrux Moderator @MegaAndy
          last edited by

          @MegaAndy said in Noisy/Fluctuating temperatures in idle since updating to RRF 3:

          if currently empty anyway.

          Is it empty? Does it exist at all? It's usually created on the first use of M500.

          Z-Bot CoreXY Build | Thingiverse Profile

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          • MegaAndyundefined
            MegaAndy @Phaedrux
            last edited by

            @Phaedrux just checked, I had actually removed the config override entirely and had never used m500 as anything I wanted changing I have put in the config.

            @Veti I will try this, I thought that's exactly how I tuned the PIDs anyway and did it fresh with RRF3.

            Still not seeing why PID tuning is relevent to temperatures fluctuating around when idle, no attempt is being made to keep a certain temperature , it's just rapidly changing without input.

            Vetiundefined 1 Reply Last reply Reply Quote 0
            • Vetiundefined
              Veti @MegaAndy
              last edited by

              @MegaAndy said in Noisy/Fluctuating temperatures in idle since updating to RRF 3:

              Still not seeing why PID tuning is relevent to temperatures fluctuating around when idle, no attempt is being made to keep a certain temperature , it's just rapidly changing without input.

              you are right at idle pid tuning does not come into play.

              have you calibrated your ADC?

              https://duet3d.dozuki.com/Wiki/Calibrating_thermistor_and_PT1000_readings

              MegaAndyundefined 1 Reply Last reply Reply Quote 0
              • MegaAndyundefined
                MegaAndy @Veti
                last edited by

                @Veti I have not heard of calibrating ADC before but it does sound promising, a quick browse of the link you sent mentions gain which sounds like a likely culprit for a noisy signal.

                I will see if I can get hold of a few resistors to work out the 100k for the H value and a 100. I'll report back once I have tried.

                Strange I have the issue now when I didn't on RRF2. Only thing I can think of is I have not set it up or kept it at room temperature like I would have when setting up on RRF2, it's kept in a garage which when I checked it this morning was about 3 degrees!

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                • Vetiundefined
                  Veti
                  last edited by

                  for the semi auto calibration you only need a jumper. try that

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                  • MegaAndyundefined
                    MegaAndy @Veti
                    last edited by

                    @Veti oh great, I glanced at that and thought it was duet 3 only, yet another thing the maestro has over its duet 2 siblings!

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                    • MegaAndyundefined
                      MegaAndy @Veti
                      last edited by

                      @Veti Unfortunately , I have tried the semi automatic ADC tuning and have not seen any improvement. H value for both came up as 0 and L was either -1 or 1.

                      Interestingly, when I had a jumper over a thermistor , rather than getting a static reading, it was jumping all over the place from 2000c to 10953c. I would have thought this should be a static number. It reported a static -273c when the port was left open which I assume is correct.

                      Even the CPU temp looks like it's jumping around quite a lot so not sure if there is simply jitter on all sensor readings. (This is also visible on the video in the first post)

                      Video with a jumper over bed heater to show rapidly changing reading. Record_2020-12-31-14-14-18.mp4

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                      • Vetiundefined
                        Veti
                        last edited by

                        ok that is not normal. i didnt even know it could go past 2000.

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                        • MegaAndyundefined
                          MegaAndy
                          last edited by MegaAndy

                          Looking like a hardware or wiring fault then I guess..

                          Found this from David on an old post: https://forum.duet3d.com/post/128645

                          I have measured 5v as a stable 4.9v and the 3.3v as stable 3.28v so I think that is ok. So could be one of the other things mentioned like leakage between bed heater and thermistor, I guess if that is the case it would be irreversible.

                          I guess at this stage the only way of proving it's not a config issue will be reverting back to old firmware with old configs to see if it still does it.

                          Edit: thought I should also mention that when I was setting up I couldn't get one fan working , on fan02, later realising the fan was just now not working as plugging another in worked fine. Makes me wonder if there was a surge at some point to cause this issue and break that fan at the same time.

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                          • Phaedruxundefined
                            Phaedrux Moderator
                            last edited by

                            Check your wiring for shorts.

                            Z-Bot CoreXY Build | Thingiverse Profile

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                            • MegaAndyundefined
                              MegaAndy
                              last edited by MegaAndy

                              I have done a bit of checking for shorts. One thing I have found is that ground and the VSSA pin of all of the thermistors are connected. I am guessing ground and VSSA should be separate?

                              They are also still joined after unplugging the thermistors.

                              Edit: Looks like according to this https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers#Section_VSSA_fuse , VSSA and the endstops ground should have under 5ohms between them, it reads 1.8ohm for me so looks correct.

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                              • MegaAndyundefined
                                MegaAndy
                                last edited by

                                I think I will just keep using it and see how it goes for now as I see no solution.

                                I have started a print and can see that despite the temperature seeming unstable at idle, when at temp it levels out to within 0.1 degrees of the requested temperature which is all that matters. I still also get a temperature blip when the bed is probed by the BL touch as shown in the graph below, reporting 15 degrees off within an instant.

                                It just seems to me that my printer in particular now seems more prone to noise/interference in temp readings than it was before.

                                Capture.PNG

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                                • Phaedruxundefined
                                  Phaedrux Moderator
                                  last edited by

                                  What's your wiring routing like?
                                  Any possibly weak crimps?

                                  Z-Bot CoreXY Build | Thingiverse Profile

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                                  • MegaAndyundefined
                                    MegaAndy @Phaedrux
                                    last edited by MegaAndy

                                    @Phaedrux The thermistors are just simply going to straight from the connectors to the hotend or bed.

                                    All wires going to the X carriage are just simply bundled together though so I guess that is prone to interference. So I guess I should be insulating the thermistor wire from the bl touch and other wires. Weird that this could be causing an issue now after updating but no issue before though.

                                    I used the connectors and crimps that came with the maestro but I wouldn't rule out me not crimping them well.IMG20210101173948.jpg

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                                    • Phaedruxundefined
                                      Phaedrux Moderator
                                      last edited by

                                      The routing looks no different than mine so I'm not sure it's the issue, but maybe there are some subtle differences.

                                      If possible try and separate out the thermistor wires to see if it improves.

                                      At least the temps seem stable when it matters.

                                      Z-Bot CoreXY Build | Thingiverse Profile

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                                      • MegaAndyundefined
                                        MegaAndy @Phaedrux
                                        last edited by

                                        @Phaedrux ok I will give that a go soon and see if I can see a difference.

                                        I feel like if the measurement from shorting the thermistor with a jumper was fluctuating like mad instead of a static reading, shows that the noise/fluctuating issue is happening with the board rather than the thermistor wire.

                                        And yes exactly main thing is they seem to be stable when at temp and not probing which is the important bit.

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                                        • MegaAndyundefined
                                          MegaAndy
                                          last edited by

                                          I am now tuning pressure advance again after retuning e-steps and find that this also causes my temperature to have massive amounts of fluctuations.

                                          I am printing the pressure advance tuning found on this forum, its alternates between 5mm/s and 70mm/s in a straight line which is seeming to cause these temperature fluctuations. Presumably the extruder motor rapidly changing speeds is causing interference with the thermistor.

                                          It's as if there used to be a filter for sensor noise but now any external factors are now causing havoc with the readings. Is there a setting anywhere for gain or noise compensation perhaps? I am wondering if there was a setting defaulted to on that now is not.

                                          a116471c-8f35-4119-9020-6d83b8d55608-image.png

                                          Once the calibration print was finished, the temp levelled out to requested temp and remained stable:

                                          b1e35d91-207d-4607-9333-45fc9276410a-image.png

                                          hackinistratorundefined Phaedruxundefined 2 Replies Last reply Reply Quote 0
                                          • hackinistratorundefined
                                            hackinistrator @MegaAndy
                                            last edited by

                                            @MegaAndy
                                            Can you try connecting the thermistor to second extruder input, just to see if its the same.

                                            MegaAndyundefined 1 Reply Last reply Reply Quote 0
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