M135 deprecated



  • We have been using several Duet controllers with stock firmware to run some prototypes incorporating a thermal system with a relatively short tau (fast response).

    The default PID interval is too slow for robust control so we have been reducing this using M135 to give us ~10Hz update rate.

    Wanting to use some of the newer features we proceeded to update to RRF v3 only to subsequently realise we are no longer able to use M135.

    Has M135 gone for good, or are there options for reimplementation?

    Could we change a hardcoded interval as an alternative?

    Cheers,

    James



  • @Cre8ic said in M135 deprecated:

    We have been using several Duet controllers with stock firmware to run some prototypes incorporating a thermal system with a relatively short tau (fast response).

    The default PID interval is too slow for robust control so we have been reducing this using M135 to give us ~10Hz update rate.

    Wanting to use some of the newer features we proceeded to update to RRF v3 only to subsequently realise we are no longer able to use M135.

    Has M135 gone for good, or are there options for reimplementation?

    Could we change a hardcoded interval as an alternative?

    Cheers,

    James

    Try the M307 F parameter



  • In RRF3 the F parameter of M307 is no longer supported. Use M950 to set the frequency when you define the heater.



  • apology's hadn't seen that sub note re RRF3 so it is the Q param on the M950 that deals with it.



  • Sort of like following the bouncing ball. I would assume that using M950 now would make it a bit more difficult to experiment on the fly with different frequencies . Haven't tried it as the default works OK for me.



  • Thanks for the replies.

    Unfortunately it’s the PID interval I need to change, M950 Q sets the the PWM base frequency.

    I should have said that we reduce it using M135 from 250ms to 100ms (so increasing the sample rate from 4Hz to 10Hz).



  • Looking at the wiki, M135 was removed in version 2.03, so quite a long time ago. The "what's new" for version 2.03 states (quote)

    "The M135 command is no longer supported, but AFAIK nobody used it"

    It seems that somebody did in fact use it.......

    This is one for DC42 I guess.



  • @DC42 might resurrecting M135 be a possibility?

    Our final goal was to integrate the Duet into a commercial product. In the meantime we can go back to v2 firmware but this isn’t really a longer term option.

    Cheers,

    James


  • administrators

    Yes I can look at re-introducing M135 or an equivalent facility. We were not aware that anyone was using it. At the time we removed it, we increased the sampling frequency from 2Hz to 4Hz.

    If you are comfortable building the firmware yourself, you can easily change it. The sampling interval is defined by this line in file Configuration.h:

    constexpr uint32_t HeatSampleIntervalMillis = 250;		// interval between taking temperature samples
    


  • Brilliant, thank you.

    We’ve not built this particular firmware before but we can certainly look at this.

    Thanks again.

    Cheers,

    James


Log in to reply