PWM logics of M307

Kaj

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

Danal

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.

Danal

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

Kaj

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

Kaj

@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

Danal

@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?

Kaj

@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.

Danal

Cool (he he). Keep us posted.