Why are my heaters gone?

  • Hi,

    I was printing successfully last night, but when I started up my printer running a Duet 2 Wifi/Duex 2 today, both the bed heater as well as the hot end heater are gone. No more tools show up in DWC.

    Here's the output of M115:
    FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 2.03 ELECTRONICS: Duet WiFi 1.02 or later + DueX2 FIRMWARE_DATE: 2019-06-13b2

    The heaters section in config.g looks just like it did yesterday:

    ; Heaters
    M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 0
    M143 H0 S120 ; set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 1
    M143 H1 S280 ; set temperature limit for heater 1 to 280C

    The hot end is an original E3D V6 (24V), and the bed heater is a 24V, 300W silicone mat powered through an MKS MOSFET.

    I tried starting a job - the bed does heat up, but the hot end remains cold. The printer goes through the motions, but doesn't extrude. DWC reads "M104: invalid tool number", "M109: invalid tool number", "Attempting to extrude with no tool selected".

    What could I do to debug this? Any help would be highly appreciated.


  • Maybe an SD card corruption problem? Looks good to you, reads differently when the machine is booting? Kinda thin, I know, but possible.

    Perhaps get a new card, format it, and build it up from scratch?

    I would definitely make, and 'eyeball' check, a backup of all the .g files in sys, ASAP. Just save them on your PC.

  • ..or it could be scrambled gcode print file. Does it behave the same way with something that you have successfully printed in the past? If the hot end doesn't heat with the message "attempting to extrude with no tool selected" that usually means the gcode file is lacking a "Tn" command. But something else is amiss if DWC thinks the tool number is "M104". Perhaps there is a lack of a line feed character after the "Tn" command so instead of (say ) T0 followed by M104 as separate commands, what is being sent is being interpreted as "TM104".

  • Thanks for the suggestions. I don't think the print file is the problem since the heaters are gone from the UI before I even start a job. I'll probably try and measure the resistance of the heater cartridge first to see if there is anything shorted or broken, and then try to rebuild the SD card from scratch. Luckily, I have a backup...

  • @lapjoint I doubt it's anything physically wrong with heaters - most likely a "scambled" SD card or rather, scrambled files. If a heater or wiring are defective it will still show on the web interface but with silly values like 2000 deg C for example. The fact that it doesn't show at all, indicates a configuration file issue.

  • Moderator

    Did you edit your config recently? There could be something in your config that’s causing the rest of it to be aborted, including the heater definitions, eg stray characters (each line must start with a Gcode or a semicolon for a comment) or invalid Gcode. If you run the config.g from the console, with M98 P”config.g” it will report any errors. Otherwise, post your whole config.g so we can check it.


  • @droftarts Thanks Ian. Good to know I can validate GCode that way. I will try that first since it's the least invasive thing to do now. I'm out until tomorrow, but I will report my findings.


  • Thanks everybody, @droftarts put me on the right track. Indeed my config.g was truncated. I was being too clever for my own good: I tried to deploy my config.g from a git repository on my computer using lftp, and it seems the config got mangled during the ftp upload.

    I re-uploaded the config through the web interface and now everything is back to normal.

    Thanks again!

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