Fan always at top speed when thermostatic control is on

cjccjj

Hi,
I have a fan connected to fan2 at the Maestro board firmware 3.4 with the following config.
It shall run at 50% when H1 hit 40C. But the fan runs full speed when temp hit 40.

M950 F1 C"fan2" Q250                    	   ; create fan 1 on pin fan2 and set its frequency 
M106 P1 S128 B1 H1 T40                       ; set fan 1 value. 50% PWM speed at 40 degree

I tried to change the S128 to S0.5, S0.6, removing B setting. But it always run full speed when reach temp.
If I turn off thermal control with H-1, and set S, it will change speed well with S parameter or DWC.

How should I change my config?
Thank you.

Phaedrux

I believe you would need to add a second temperature to create a range for it to start and increase until the higher temp is reached.

M106 P1 S128 B1 H1 T40:60

cjccjj

@Phaedrux
Thank you and sorry for the late response. I think you are right, while the documentation might need some updates.

*"
Examples

M106 S127
M106 P1 T45 S0.7 H1:2
M106 P1 T40:50 H1:2

The first example turns on the default cooling fan at half speed. The second example sets the second fan to a thermostatic fan for sensors 1 and 2 (e.g. the extruder heaters in a dual-nozzle machine) such that the fan will be on at 70% PWM when either hot end is at or above 45C. The third example also sets up a thermostatic fan, but this time it runs in proportional mode. "*

The second example from the docs is what I tried but doesn't work. The third example in proportional (range) mode didn't explain at what proportional it work.

The older documents dozuki has some more explanation that the lowest starting speed in proportional is 50%, and if I didn't get it wrong, the starting speed can be set by S parameter. But appears it doesn't work so with my setup.

Phaedrux

What commands are you using now and what behaviour are you seeing?

cjccjj

I was using this fan as a hotend cooling fan, it is too strong and loud therefore I don't want it always running and was trying to limit it speed at 50% when printing. I end up using L and X with M106 to achieve this.

M106 P1 L127 X128 S255 B1 H1 T40

I didn't try the code further as it is difficult to judge the actual speed of a fan just by listening to it noise, and I found that PWM control on 2 pins normal fan isn't working really well. So then I changed to another lower speed fan and let it run at 100%.

However, I think documentation on how to use range / proportional fan control does need some work.

droftarts

The change in fan behaviour happened in RRF 3.4:

When a fan is configured as thermostatic using M106, the S parameter is now ignored. If a single T value is given, then when the temperature is above the T parameter the fan will run at the PWM specified by the X (maximum PWM) parameter (default 1.0).

This change was made because there were many users complaining that their thermostatic fan didn't come on, but had S0 set eg M106 P1 T45 S0 H1. Now it comes on at 100%, and is limited by the X parameter, so M106 P1 X128 H1 T45 would be the correct way to do this in 3.4.

I have updated the M106 documentation to reflect this.

Ian

Tinchus

@droftarts I have a fan controlled by temperature:

M106 P2 L35 H5 T40:43

This line is OK in 3.4.4? objective there is to turn on the fan at 35% when temp is 40 degrees, then go up till 43 degrees.

Hearing the fan is not accurate for me to say if it is working ok or not jajajaja

droftarts

@Tinchus Yes, that looks okay. It should turn on at 35% PWM at 40C, and ramp up proportionately to 100% at 43C.

Ian