RRF3 limit max heater PWM?
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need to run a 12V heater on a 24V rail "for a few weeks" ... dual extruder setup, one heater is 24V other is 12V, is there a way to setup one heater to never use more than 50% pwm? I don't see that M950 have this option ... not a big issue if not possible but would skip adding external hw if I can solve it in fw
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@smece I will assume here that you know it is highly discouraged to use 12V heaters with 24V power supply. Also you would need to limit it to 25% and not just 50. PWM limit is not applied via
M950
but viaM307 Snnn
parameter. In your case that would beM307 S0.25
. But again: not a good idea - but I think you know that already. -
yes, not a good idea, I agree 100% but I'm waiting for new ones to arrive and I wanna do some simple tests where this would be acceptable ... 50% will do these are low power heaters with 50% pwm of 24V they will be just fine
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@smece said in RRF3 limit max heater PWM?:
50% will do these are low power heaters with 50% pwm of 24V
if you double the voltage you quadriple the power.
so you would be running a 30W heater at 120W at full power.
that is why @wilriker said 25% -
@Veti said in RRF3 limit max heater PWM?:
if you double the voltage you quadriple the power.
so you would be running a 30W heater at 120W at full power.
And consequently a 12V 30W heater will be running at around 60W with 24V 50% PWM.
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@smece said in RRF3 limit max heater PWM?:
need to run a 12V heater on a 24V rail "for a few weeks" ... dual extruder setup, one heater is 24V other is 12V, is there a way to setup one heater to never use more than 50% pwm? I don't see that M950 have this option ... not a big issue if not possible but would skip adding external hw if I can solve it in fw
This is possible using the S parameter of the M307 command. But as others have noted, it is also unsafe. The printer should most definitely not be left unattended.
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it's crappy 18W heater on the huge piece of alu block so no worries, it's plenty safe, and everything is not even in beta stage so nothing is unattended and I have a finger on the power non-stop ... it's just that I missed M307 as there's "update" on the rrf3 page not mentioning S so I didn't bother to check main gcode doc to read the rest of the parameters that didn't change so I wrote here ... as for ohm's law It's been 30years since I learned it but those things you don't forget that easy
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actually 12W, even worse in theory it would behave like ~50W 24V but not sure how good the inside of it is (I seen some where there's huge gap between wires and outter metal, no sand/ceramic/fire-cement between thermal wire and casing) and in case is not good it can burn out... so I wanna control the max pwm output for just in case .. 50% will do the trick (mind, I'll start with 10% to test if it works at all taking into account the firmware is beta too)