M140 Heater Fault Error

pete1961

@jay_s_uk
During bed heater tuning I noted the accurate temperature is far off.
When the Duet board thinks it's 90°C it's actually about 58°C.
What parameter needs to be changed to correct for this difference?

jay_s_uk

@pete1961 use the correct thermistor settings?
how are you actually measuring the actual temperature reading? what type of heated bed is it? where are you measuring the temperature compared to the placement of the thermistor?

pete1961

@jay_s_uk
Measuring the Bed Temp with a FLuke IR Thermometer.
It has always been accurate.
The thermistor is directly in the center of a 12" X12" heated bed made from a PCB board.
It essentially worked until I upgraded the firmware and re-did my setup from scratch using the config tool.
So I'm of the belief it is related to a setting in my config file and not hardware related as everything was working correctly previously.

Phaedrux

@pete1961 said in M140 Heater Fault Error:

Old firmware worked fine until it was corrupted and re-installed latest firmware.

What do you mean corrupted? Do you still have your config files from before?

pete1961

@Phaedrux I do still have them from before but they are old and use different commands because the firmware was quite old.

Phaedrux

Yes but those files will have a working configuration we can compare against.

pete1961

@Phaedrux
Okay just ran a PID Calibration on the Bed afterwards when trying to print received error stating bed was taking to long to heat up.

After running the bed calibration my M307 is H0 R0.582 K0.393:0.000 D14.47 E1.35 S1.00 B0

The OLD M307 before that was know to work was M307 H0 R0 .554 C309.6 D11.90 S1.00 B1 V11.8

Also I now believe the thermistor does read correctly after checking it again.

So I'm not sure why the printer is slow to heat up. Any ideas?

Phaedrux

@pete1961 said in M140 Heater Fault Error:

M308 S0 P"bedtemp" Y"thermistor" A"Heated Bed" T100000 B3950 ; configure sensor #0

Does your new thermistor configuration match your old one?

Are you sure it's matching your exteral temperature sensor now?

After you did the tuning, did you save the results with M500? Do you have M501 in your config.g to load them at startup? Or did you manually enter the M307 command into your config.g?

What does your heater graph look like during the heatup phase and when the error results?

Did you tune when the bed was dead cold?

luca Massimiliano

good morning, I hope that posting my question like this is correct. I have a heater that stays on at the end of printing, the other one turns off, how can I turn it off automatically?

droftarts

@luca-Massimiliano said in M140 Heater Fault Error:

good morning, I hope that posting my question like this is correct. I have a heater that stays on at the end of printing, the other one turns off, how can I turn it off automatically?

No, it's not correct. Please start a new thread.

Ian

pete1961

@Phaedrux
I replaced the thermistor which solved the erroneous temperature readings.
I did a PID Tune and it went fine and appeared like everything was in order.
During the printing of the first part after tuning my 80AMP SSD Relay overheated, melted and self destructed. This is not the first time this has happened either.
I have the relay being controlled from the Duet2wifi Heater Output and power for the bed being supplied from a 12VDC Power Supply.
What would cause these relays to fail? What is the remedy to avoid this from happening?

droftarts

@pete1961 Most likely the PWM frequency was too high for the SSR. It's set by the Q parameter in the M950 command that defines the heater pin:
https://docs.duet3d.com/User_manual/Reference/Gcodes#m950-create-heater-fan-spindle-led-strip-or-gpioservo-pin

Qnn (optional) PWM frequency in Hz. Valid range: 0-65535, default: 250 for heaters. Max value for heaters 1000, to avoid overheating the mosfets.

Check the rating of the SSR, adjust Q as required.

Ian

Phaedrux

@pete1961 said in M140 Heater Fault Error:

12VDC

Might want to look at upgrading your bed to 24v, or even AC. Low voltage high wattage heaters have a high current draw.

pete1961

@droftarts
Can you explain how or where to adjust "Q".
I don't see it as a parameter for M307.
The SSR is rated for 80 amps.

dc42

@pete1961 said in M140 Heater Fault Error:

During the printing of the first part after tuning my 80AMP SSD Relay overheated, melted and self destructed

What make and model of SSR was it? There are a lot of fakes about, especially Fotek. The Auber Instruments ones are good.

@pete1961 said in M140 Heater Fault Error:

Can you explain how or where to adjust "Q".

It's a parameter to the M950 command that you use to assign the heater port. We suggest Q10 for driving SSRs.

droftarts

@pete1961 It's in the M950 command that defines the heated bed control pin. Yours, from your first post, is:

M950 H0 C"bedheat" Q100 T0 ; create heater #0

So it's already at 100Hz, ie switching at 100 times a second. Change it to Q10 as @dc42 suggests.

Ian

pete1961

@dc42
Thanks for the feedback.
It is a cheap Fotec but was purchased from Amazon.
So I know they are all considered junk.
I just recently purchased an Auber Relay knowing this after these other cheap Chinese ones keep melting! They have done so multiple times over the last few years.
Knowing that I will use M950. So this is in place of M307 is that correct?

Phaedrux

@pete1961 said in M140 Heater Fault Error:

So this is in place of M307 is that correct?

No. It is in addition to M307.

pete1961

@Phaedrux said in M140 Heater Fault Error:

@pete1961 said in M140 Heater Fault Error:

So this is in place of M307 is that correct?

No. It is in addition to M307.

Got it!
Let me try it!
Does it come in after M307 or before?

Phaedrux

M950 H0 C"bedheat" Q100 T0 ; create heater #0

Just edit your existing M950 command for the bed heater in config.g to change Q100 to Q10. That's all.