Disable PWM on heater 0

maytasjohn

Hello,

I have 230V heatbed connect to relay controlled by out1. I get PWM in the relay, which I don't want. How can I turn off PWM on heater?

Thank you.

giostark

@maytasjohn
Hi, maybe I'll say improper stuff but I try to help anyway. Hope skilled will join the 3d.

The output of "E0/E1 heater" are adapting by nature in function of the correlated thermistor. If the temperature is reached the signal will come cut for make activated again few instant later for keep the temperature at the desired level. So is not constant.
So the relay must be fast or suited for continuous open/close. The SSR make a wonderful job.
Any SSR DC/AC with the right amperage flow will be good. (they are mono-static - normally open)

But maybe in your chain some electronic is slow and doesn't like a fast open/close so you could prefer a continuous signal.
For this case you can use the related fan signal of the desired heater.
https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans
Ex from the wiki:
M106 P1 T45 H1
This sets fan 1 to run any time the temperature of heater 1 is above 45 Celsius. See M106 for details.
We recommend you use the FAN1 connector for a thermostatically-controlled hot end fan,
because on the Duet 2 WiFi / Ethernet in RRF 2.x it defaults to being on at power up ,
to provide maximum safety if you restart your Duet when the hot end is hot.

https://www.reprap.org/wiki/G-code#M106:_Fan_On

M950 F1 C"fan0" ; tool fan declaration
M106 P1 S1 X1 H1 T40 ; turn on that fan

This will offer a continuous signal after the 40 degree till the temp will stay over this number.

T3P3Tony

@maytasjohn use bang bang control:

https://duet3d.dozuki.com/Wiki/Gcode#Section_M307_Set_or_report_heating_process_parameters

Bn selects Bang-bang control instead of PID if non-zero. Default at power-up is 0 for extruder heaters, 1 for the bed heater.

fcwilt

@maytasjohn

How do you plan to control the heater if you turn off "PWM"?

Keep in mind that the alternate control method of "bang-bang" is really just PWM at a very slow rate.

For my 110 VAC bed heater I use a SSR (solid state relay) in PID mode at 10 Hz at it works just fine.

Frederick