Heater output not working
-
I have a duet 3. I am controlling my heater using a SSR relay. I recently changed my thermocouple from PT100 to K-type (I am using a 31856 daughter board). Now I can not get the heater to work. When I make the heater active, the LED on out0 does not turn on. What am I doing wrong? Here is how my heater is setup in config file.
; Heaters
M308 S0 P"spi.cs0" Y"thermocouple-max31856" ; configure sensor 0 as thermocouple via CS pin spi.cs0
M950 H0 C"out0" T0 ; create bed heater output on out0 and map it to sensor 0
M307 H0 A145.6 C1611.7 D10.5 V28.8 B0 S1.00 ; PID parameters for heater bed
M140 H0 ; map heated bed to heater 0
M143 H0 S400 ; set temperature limit for heater 0 to 400C -
Do you have VIN applied to the input ports next to Out0?
Does your temp reading show accurately?
How exactly are you trying to make the heater active?
Is the thermocouple the only thing that's changed recently?
-
@phaedrux The VIN is definitely applied to the input port. I think the problem is not VIN because the led for out0 does not turn ON at all when I make the heater active. It should turn ON regardless of whether VIN is applied or not when I make the heater active. I tried to verify if there is an issue with the output itself by assigning it as a pin 5 in config (M950 P5 C"out0"). I see that the LED turns ON as it should when I send M42 P5 S1.
Temperature reading is showing accurately.
I am trying to make the heater active by clicking on "Heater" on the DWC dashboard so that it shows the status active or by entering a value for temperature on the Dashboard and then hitting enter.
I have 3 printers running on Duet 3. For 2 of my printers, I changed the thermocouple and the daughter board along with corresponding changes to the config file after which I started seeing issues. For the 3rd printer, I have not made any changes to the hardware. I only tried to change the output pin from out0 to out1. Neither that worked nor out0 is working on the 3rd printer as well even when I did not change any hardware on the 3rd one. I did update the firmware on all printers recently but all of them were working after that until now after the update.
So now I am even more confused.
-
@anagh said in Heater output not working:
I think the problem is not VIN because the led for out0 does not turn ON at all when I make the heater active. It should turn ON regardless of whether VIN is applied or not when I make the heater active
Not so. The LED is connected to the bed heater output, so it will only be on if the heater is turned on by firmware and power is applied to the bed heater power input terminals.
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 -
@anagh said in Heater output not working:
31856 daughter board
Try commenting out the M307 line for now?
And check the blade fuse next to the heater terminals.Also, add "Q10" to the M950 if you are controlling a heater from an AC power source via an SSR.
That sets the PWM frequency to 10Hz; the default is far higher than AC power frequency so does not properly control an SSR, which can only switch at each AC half cycle time.
Re-run the heater tuning once it's working, to allow for the changed PWM interactions.
-
@rjenkinsgb adding Q10 to M950 worked when using PT100 sensor. I see the LED for out0 turn ON and the temperature go up.
When I changed to K type thermocouple and to max31865 daughter board (along with corresponding change to the config file same as mentioned in the question above), the heater does not turn ON. out0 LED also doesn't turn ON. I checked that Vin is definitely applied and the temperature also seems to be accurate.
-
@dc42 Okay, got that. But still struggling with getting the heater to work with K-type thermocouple and the daughter board.
-
So i figured out the issue on 2 of my printers. Honestly, not sure what worked, but 2 of them are working. But on one printer, it seems like there is an issue with out0. I can not get it to switch the heater ON. When I turn the heater active, I dont see any potential across out0 terminals. I checked the fuse on out0 and it is fine.
If I change out0 to out1, in my M950, that works. Can I use out1 instead of out0 to drive the SSR which drives my AC heater? Is there any downside to that? -
Do you see power coming in from vin to the out0 input terminals?
Fuse is ok?@anagh said in Heater output not working:
Can I use out1 instead of out0 to drive the SSR which drives my AC heater? Is there any downside to that?
Yes you can, there is no downside when using an SSR.
-
@phaedrux Power is coming in to the out0 inputs and the fuse is also fine.
-
Can you switch back temporarily to using the PT100 daughterboard or even a plain thermistor just to take the thermocouple out of the equation? If that is the change that precipitated the out0 not working anymore, perhaps reversing that change would allow it to work again. Or perhaps that's just a coincidence and the mosfet is damaged.
