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    Error: Heater 0 fault: temperature rising much more slowly ...

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    • A Former User?
      A Former User @chuser
      last edited by A Former User

      @chuser said in Error: Heater 0 fault: temperature rising much more slowly ...:

      @LB the temp diagram is shorter

      Just to be sure: Do you have a config-override.g and if you have one does it get loaded e.g. at the end of your config.g?

      chuserundefined 1 Reply Last reply Reply Quote 0
      • chuserundefined
        chuser @A Former User
        last edited by

        @LB

        yes i have a config-override.g the content is as follows:

        ; config-override.g file generated in response to M500 at 2021-03-15 13:34
        ; This is a system-generated file - do not edit
        ; Heater model parameters
        M307 H0 R1.911 C66.100:66.100 D1.19 S1.00 V24.1 B0
        M307 H1 R4.902 C144.300:144.300 D7.31 S1.00 V24.2 B0
        

        and in the config.g at the end M501
        is that correct?

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        • Phaedruxundefined
          Phaedrux Moderator @chuser
          last edited by

          @chuser Photo of how you have the heater mounted?

          Z-Bot CoreXY Build | Thingiverse Profile

          chuserundefined 1 Reply Last reply Reply Quote 0
          • chuserundefined
            chuser @Phaedrux
            last edited by

            @Phaedrux on OUT0 PIN 1&2
            IMG_0567.jpeg

            IMG_0568.jpeg

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            • chuserundefined
              chuser
              last edited by

              I now know that it is a semitec104gt thermistor. But I have not yet solved the problem.

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              • Phaedruxundefined
                Phaedrux Moderator
                last edited by

                And you've updated your config.g to use the semitec thermistor values?

                Z-Bot CoreXY Build | Thingiverse Profile

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                • chuserundefined
                  chuser @Phaedrux
                  last edited by

                  @Phaedrux yes i did. but did not help

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                  • Phaedruxundefined
                    Phaedrux Moderator
                    last edited by

                    And did you re-tune after changing the values?

                    Z-Bot CoreXY Build | Thingiverse Profile

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                    • Phaedruxundefined
                      Phaedrux Moderator
                      last edited by

                      It may help to increase the dead time. Try going from D1.19 to D10.

                      May also try decreasing the gain from R1.911 to R1

                      Z-Bot CoreXY Build | Thingiverse Profile

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                      • chuserundefined
                        chuser
                        last edited by

                        All these test were with the new config.

                        M308 S0 P"temp0" Y"thermistor" T100000 B4725 C7.06e-8
                        

                        I have made a few tests with different PWM values.

                        M307 H0 R1.726 C184.233:184.233 D1.53 S1.00 V24.1 B0 ; 1.00 PWM
                        M307 H0 R1.712 C169.414:169.414 D1.31 S0.80 V24.1 B0 ; 0.80 PWM
                        M307 H0 R1.703 C173.799:173.799 D1.23 S0.75 V24.0 B0 ; 0.75 PWM
                        M307 H0 R1.651 C161.829:161.829 D0.99 S0.60 V24.2 B0 ; 0.60 PWM
                        M307 H0 R1.499 C169.336:169.336 D0.79 S0.50 V24.2 B0 ; 0.50 PWM
                        

                        With S0.5 it works. But the heating up goes very very long.

                        @Phaedrux
                        Then I tested with increased dead time, but it did not work.

                        M307 H0 R1.726 C184.233:184.233 D10 S1.00 V24.1 B0
                        

                        Then I tried to decreasing the gain, and this work.

                        M307 H0 R1.0 C184.233:184.233 D1.53 S1.00 V24.1 B0
                        

                        I can't believe it.

                        Can I leave it set like this? Or does this still need to be optimized?

                        Phaedruxundefined 1 Reply Last reply Reply Quote 0
                        • dc42undefined
                          dc42 administrators @chuser
                          last edited by dc42

                          @chuser said in Error: Heater 0 fault: temperature rising much more slowly ...:

                          @Phaedrux the Heater is this one

                          24V ~60W

                          https://well-engineered.net/index.php/en/90-new-kapton-heater

                          Bild Text

                          Is that the thermistor in the centre of the heater?

                          If so then I think the problem is that the new algorithm doesn't work well with heaters having a large reservoir effect. Your temperature plot of the tuning supports this. By "reservoir effect", I mean that the thermistor is coupled fairly tightly to the heater, and less tightly to a large heat reservoir, in this case the bed plate. This means that the FOPDT model breaks down and there are in effect two values for the heating rate or gain: a short term value (which is what the new algorithm measures) which is the heating rate when the reservoir is close to the target temperature, and a long term value which is the heating rate when the reservoir is very different from the target temperature.

                          The ideal solution is to use a thermistor that is coupled to the bed plate (the thing you are trying to heat) instead of the heater. This will also give you better temperature control. However, as a workaround you can reduce the R value in the M307 command. Try reducing it by 30% or if necessary 50%.

                          I have it in mind to modify the algorithm to measure the long-term heating rate as well as the short term one, and use the long term rate when monitoring for a heater fault.

                          Duet WiFi hardware designer and firmware engineer
                          Please do not ask me for Duet support via PM or email, use the forum
                          http://www.escher3d.com, https://miscsolutions.wordpress.com

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                          • Phaedruxundefined
                            Phaedrux Moderator @chuser
                            last edited by

                            @chuser said in Error: Heater 0 fault: temperature rising much more slowly ...:

                            Then I tried to decreasing the gain, and this work.
                            M307 H0 R1.0 C184.233:184.233 D1.53 S1.00 V24.1 B0

                            I can't believe it.
                            Can I leave it set like this? Or does this still need to be optimized?

                            What does the heat graph look like with those values? If the temps are stable, you can continue to use it.

                            Z-Bot CoreXY Build | Thingiverse Profile

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                            • dc42undefined
                              dc42 administrators
                              last edited by

                              Decreasing the gain or heating rate parameter will fix the "temperature rising too slowly" error. It might have the side-effect of causing the temperature to oscillate slightly. If so, then increase the dead time parameter enough to stop the oscillations.

                              Duet WiFi hardware designer and firmware engineer
                              Please do not ask me for Duet support via PM or email, use the forum
                              http://www.escher3d.com, https://miscsolutions.wordpress.com

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