230v heatbed protection

Hello everyone.

My printer is equipped with 230v silicon heatbed and I want to make an additiona protection in case of SSR fails
I mean is it possible to add an extra code for switch power OFF when heatbed will exceed 150C
of course I have activated POWER_SUPPLY and additional circuit with relay for switching the printer on and off using M80 and M81
eg.

If heatbed_temperature >= 150
then PS_power_OFF

Thanks a lot for reply

It might very well be possible.

Are you using Marlin 1.1.9 or 2.0.X?


- For 1.1.9 - In file Marlin_main.cpp - at the very bottom of the file

Replace:

  idle();
}

With:

  idle();
  #if (HAS_POWER_SWITCH  && HAS_HEATED_BED)
  	  if (thermalManager.degBed() >= 150) { PSU_OFF(); }
  #endif
}

- For 2.0.x - In file Marlin.cpp - at the very bottom of the file

Replace:

   idle();
  }
}

With:

    idle();
    #if (HAS_POWER_SWITCH  && HAS_HEATED_BED)
        if (thermalManager.degBed() >= 150) { PSU_OFF(); }
    #endif
  }
}

What ever version of Marlin you are using.
- you might want to test with setting the limit to for example 50,
- and turn on your bed, to go higher than 50

And see if the PSU gets turned off when the temp reaches 50*C


I have not tested the suggested code, beyond making sure that it can compile, so I will be interested to hear if this code actually does what you are requesting.