Error: Heater 0 fault

Festivejelly

Im getting periodic fails when running a print. Its very frustrating because I see the bed heating up but because its not within 0.7 degrees per second I get a failure.

Error: Heater 0 fault: temperature rising much more slowly than the expected 0.7°C/sec

I've tried reading the docs and I must say its far more complicated than the marlin autotune which just works...

I run an auto tune as per https://duet3d.dozuki.com/Wiki/Gcode#Section_M303_Run_heater_tuning

I have a AC heated bed (e3d tool changer)

And ive set the results of the PID rune in my config file:

; Heaters
M308 S0 P"bedtemp" Y"thermistor" A"Bed" T100000 B4138 C0 ; Set thermistor
M950 H0 C"bedheat" T0 Q10 ; Bed heater, set to 10hz https://forum.duet3d.com/topic/17943/bed-heating-issue-now-that-i-m-on-3-1-1/17
M143 H0 S225 ; Set temperature limit for heater 0 to 225C
M140 H0 ; Bed heater is heater 0
M307 H0 R1.484 C389.1 D2.12 S1.00 V0 B0 ; PID Tuning

Im printing at 250c, and 85 on the bed. It heats the tool fine but as it gets to around 80c on the bed it just errors even though its still creeping up.

Im running 3.2.2 Any ideas? Im tearing my hair out here, it shouldnt be this hard so I keep thinking ive missed something obvious but ive followed the docs guidance and it still doesnt work.

T3P3Tony

@festivejelly what were the results from the autotune?

If you bed can't achieve 0.7 degrees/s that is odd. I use the e3d toolchanger AC bed and got the following from M303 (just checked again now with another tune):
M307 H0 B0 R1.467 C307.1 D2.23 S1.00 V24.1

Festivejelly

@t3p3tony well it can. Thats the issue. Its the speed at which its doing it right at the end I guess isnt inline with the 0.7 degrees per second. Maybe due to the pid tuning setup. If I disable the pid settings and heat up the bed i heats up super fast but has an oscillating value.

Sometimes it works just fine and I can go for days without having problems. But other times I get the error. It feels to me like its a bit too sensitive. I wonder if I can give it a bit more leeway when heating up. Im only really want it to to throw the error if it doesnt stabilise. But it doesnt exactly give it much time to do that.

T3P3Tony

@t3p3tony said in Error: Heater 0 fault:

what were the results from the autotune?

not sure if the M307 values you show in the earlier post are what autotune gave you.

Possibly you have a bit more noise in your temperature sensing than I do on mine if it only errors occasionally.
You can tweak them to be less sensitive as described here:
https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control#Section_Manual_adjustments_to_the_heater_model_parameters

Also you can increase the time before a fault is raised if it is very quick:
https://duet3d.dozuki.com/Wiki/M570

Festivejelly

@t3p3tony

This is the result of the auto tune:

M307 H0 B0 R1.389 C386.0 D2.07 S1.00 V24.3

What I have noticed is if I heat the bed first then the tool I get no errors. I was seeing errors when Cura was annoyingly injecting start gcode to heat the tool before the bed. Im not sure how that would have an affect though since its an SSR so the 24v supply shouldnt be affected.

T3P3Tony

@festivejelly yes that should not have an impact unless the hotend is noisy and the noise is transferred onto the temperature circuits making the bed readings noisy. Your results are very similar to mine from the autotune so i don't think they are invalid. Have you tried increasing the window before it faults to longer than it takes to get everything heated to a stable temperature?

Festivejelly

@t3p3tony I've not tried that yet but ill look into that.

tbh now im just preheating the bed before each print it isnt really manifesting anymore but I shall keep that in mind thanks for the help.

Festivejelly

@festivejelly said in Error: Heater 0 fault:

@t3p3tony I've not tried that yet but ill look into that.

tbh now im just preheating the bed before each print it isnt really manifesting anymore but I shall keep that in mind thanks for the help.

Spoke too soon now its just randomly doing it on just normal preheats too. This really shouldnt be that difficult. Im considering just flashing Klipper onto it instead.

T3P3Tony

@festivejelly please send a picture of the temperature.graph when this is happening and the errors you get in the console.