Large Dual Bed Heaters cannot PID tune
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Hi there, I've been battling with this issue for a while. I can work around it by resetting the temperature faults and getting to 80 degrees but this time consuming and I dont have the time to sit and wait for temps to go up. The bed still reaches 80 degrees and used to work automatically, all of a sudden it stopped working and get the faults. There are two heaters that work independently.
Error: Heater 0 fault: temperature rising much more slowly than the expected 0.02°C/sec.
I cannot run a tune as it times out.The only change might of been when I changed the mother boards out and the firmware updated from 3.2 to 3.4?
Any help would be appreciated
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@Skan there was a change in the heater PID algorithm between 3.2 and 3.4
You can manually change the tuning settings as per this https://docs.duet3d.com/en/User_manual/Connecting_hardware/Heaters_tuning#manual-adjustments-to-the-heater-model-parameters
the dead time is the one to adjust
this might also be a good read https://docs.duet3d.com/en/User_manual/Troubleshooting/Heater_faults -
@jay_s_uk Thankyou looks like when I increased D Value and then increased M570 values for the bed its working ok (less alarm faults). Still not perfect but much more manageable.
The AutoPID Tune M303 still faults out as it takes too long, is there anyway to change the timing on this? it is a large and thick bed, would you recommend manually setting the parameters?How do I input the changes into G.code file or will the M500 function work to save on g.override?
Thankyou
Regards
Saad -
@Skan i'm not sure the timeout on the PID tuning can be adjusted
I usually just save the settings using M500.
If you'd rather, you can just use the M307 line in config.g after the heater has been created with M950 and M308
