Heater auto tuning question



  • I am trying to figure out auto tuning and sent the following:
    M303 H1 S240

    This was the result:
    Auto tune heater 1 with PWM=0.50 completed in 300 sec, maximum temperature reached 199.5C
    Heater 1 model: gain 381.6, time constant 104.1, dead time 3.4, max PWM 1.00, mode: PID
    Setpoint change: P14.5, I0.139, D34.1
    Load change: P14.5, I1.602, D34.1

    I sent M500 and this is my firmware version:
    Firmware Electronics: Duet WiFi 1.0
    Firmware Version: 1.17e (2017-02-10)

    The WIki mentions that the settings will be saved in config-override.g. I see my config.g file but don't see config-override.g. Of course, I am confused again. So, I powered down the printer and sent M307 H1, and sure enough, the settings do not appear to have been saved. But, I now see the config-override.g file! And, for the heater I ran auto tuning on, it shows this in the config-override.g file:
    M307 H1 A381.6 C104.1 D3.4 S1.00 B0
    So, the correct values are there, according to the procedure shown in the Wiki. Sending M307 H1 again, shows the old values.

    So, have a bunch of questions resulting from the confusion…

    What is the purpose of the config-override.g file? If it's there, does that mean my heater has been tuned and will operate accordingly?

    Or, do I need to edit the config.g file with M307 H1 A381.6 C104.1 D3.4 S1.00 B0? If so, where in the config.g should I put it?

    Thank you in advance for the assistance!


  • administrators

    You should add command M501 near the end of config.g to invoke config-override.g.



  • Thanks, that worked. However, this below is also in the config-override.g file:

    ; Z probe parameters
    G31 T1 P500 X0.0 Y0.0 Z2.65
    G31 T3 P500 X0.0 Y0.0 Z0.70
    G31 T4 P500 X0.0 Y0.0 Z0.00

    While I'm a little slow and would just ignore this, I noticed that the first line "Z2.65" is exactly the value I have in my config.g file. I periodically adjust this value to adjust z-height for first layer stick issues. I'm assuming the values in the config-override.g file are stored in EEPROM. I've put in the M501 command at the end of config.g. So, if the Duet Wifi powers up, and looks at config.g, must I change the values in config.g and config-override.g if I need to change my z-offset value?


  • administrators

    The simplest way for you to make trigger height changes is to send the G31 Zxxx command to change the trigger height, then send M500 to save it (along with the current heater model, which you won't have changed) in config-override.g.



  • Good morning David,
    Thanks once again for the assistance. So, I got the bed heater tuned and sent M500…that updated the config-override.g file so all seems good.

    I then tried to edit the trigger height by sending G31 Zxxx...then M500 to save. That changed the height in the config-override.g file but NOT in the config.g file. Does this matter if it's not changed in the config.g file?

    FYI, for anyone having the same questions as me, it seems the M500 command did not work until a config-override.g file existed. I followed the instructions on the Wiki regarding auto tuning, etc. as best I could but a config-override.g file did not exist on my setup. I had to cycle power to the printer and then, for whatever reason, the config-override.g file was then created.



  • So, I've been playing around with the G31 Zxxx and M500 commands. I tried it a couple of times and it seemed to edit the config-override.g file (but not the config.g) and when I home Z, the height displayed on DWC would correspond the the value I input. After a few tries, the height shown on DWC is 0.1mm less than the value I input. Once again…confused!



  • Well, once again, a reboot seemed to fix the issue. Now, the input Z height matches what's shown on DWC. I've also discovered that the Duet Wifi seems to disregard the Z height in the config.g file and now uses what ever value is in the config-override.g file. I guess it looks at the config-override.g file after initially looking at the config.g?


  • administrators

    Your config.g file should have a M501 command near the end, which causes config-override.g to be run. So the values in config-override.g override earlier settings in config.g.


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