PWM logics of M307



  • Hi Everyone,

    I was getting error because my bed heated up slower than the expected 1.7°C/s
    I tried autotuning but apparantly it failed somewhere during phase 4.

    I changed the PWM value to 2 and haven't had the error since but I'd like to know what it actually does.

    M307 H0 B1 S2.00

    Kind regards,

    Kaj



  • Given that the documentation for M307 says:

    Snnn maximum PWM to be used used with this heater on a scale of 0 to 1. Default 1.0.

    That S2.00 is likely doing nothing. The default was 1.0 and I'd bet that setting it beyond 1 just sets it to 1. Further, I'd bet that the non-error is because the bed was not totally, completely, cooled to room temp when you experimented further.

    I would HIGHLY recommend running an autotune, and putting the resulting parameters in config.g.



  • Oh, and your question: S being scaled 0 to 1, and called "Max PWM", it looks like it is the maximum duty cycle for PWM on the heater specified.

    See "duty cycle" here



  • @Danal sounds plausible to why the error didn't occur anymore. I'll retry tomorrow with a cold bed and report back.



  • @Danal I just retried with a cold bed and heated up to 70 without getting the error.
    I'm printing now so I'll try again tomorrow after setting it back to 1



  • @Kaj said in PWM logics of M307:

    @Danal I just retried with a cold bed and heated up to 70 without getting the error.
    I'm printing now so I'll try again tomorrow after setting it back to 1

    Sounds good. Did you ever run a calibration?



  • @Danal I did yeah, it went to phase 4, was cooling down for a while and later when I checked it had an error in phase 4.



  • Cool (he he). Keep us posted.


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