Pressured air cooling controlled with servo and ball valve

o_lampe

@owend
I just found this thread, please see my reply there

o_lampe

@OwenD and @MaxGyver
Thinking further and having pity with the servo, it would be better to add a 'hysteresis' in the code, such as

[pseudo code]
If (abs(new_fan_value - old_fan_value) > hysteresis)
   go on
else
  break

That's not necessarily a problem with fan-values changing in big numbers, but a Servo also has a'deadband' which you have to keep in mind. (and for further reference, if someone wants to reuse the code for something else)

MaxGyver

@owend

I am getting the following error after inserting your code in my config.g

"Error: Failed to read code from macro config.g: Failed to parse major G-code number (lobal) in line 85"

To me, it looks like the global variable are not recognized by the firmware:

I am using firmware version 3.3-b2.

o_lampe

You have written servoout and also servo_out.

MaxGyver

@o_lampe said in Pressured air cooling controlled with servo and ball valve:

You have written servoout and also servo_out.

Nope, this did not cause the error...

"Error: Failed to read code from macro config.g: Failed to parse major G-code number (lobal) in line 4"

;Valve Control
; Set up scaling variables {(output_end - output_start) / (input_end - input_start)}
M950 S1 C"io4.out"  ; assign GPIO port 1 to heater4 on expansion connector, servo mode
global InputStart = 0 
global InputEnd = 1
global OutputStart = 0
global OutputEnd = 90
global ScaleFactor = (global.OutputEnd - global.OutputStart) / (global.InputEnd - global.InputStart) ; no need for the math in this instance but it makes it clear how you arrive at the value.
global ServoOut = floor(global.ScaleFactor * (fans[0].actualValue - global.InputStart) + 0.5) + global.OutputStart ; calculate position required on sevo - use floor() to apply rounding
M280 P1 S{global.ServoOut} ; adjust valve position to reflect fan speed.

OwenD

@maxgyver
@maxgyver
I'm assuming you are running the correct versions on DWC, etc etc
We are both running RRF3.3b2 and it works for me.
I'm on a Duet 2 wifi.
I don't have a duet 3, but I suspect it's actually coming from your M950 command on the previous line.
Either that are it's one of this SBC specific issues.

What happens when you run those commands individually from the console command line?

OwenD

@o_lampe
That was actually my error in the original.

o_lampe

@maxgyver said in Pressured air cooling controlled with servo and ball valve:

G-code number (lobal)

Your parser believes global is the beginning of a move command and it can't parse "lobal" as number (0,1,2,3,4 expected)
I'm with @OwenD it might be related to SBC issues.

MaxGyver

@owend said in Pressured air cooling controlled with servo and ball valve:

(...)I suspect it's actually coming from your M950 command on the previous line.
Either that are it's one of this SBC specific issues.

It's not the M950 command (I have checked by commenting out this line)

@owend said in Pressured air cooling controlled with servo and ball valve:

What happens when you run those commands individually from the console command line?

I get the same error message.

-Max

MaxGyver

@maxgyver

After upgrading to Beta3.3 the error message has changed to the following:

the code in config.g:

;Valve Control
; Set up scaling variables {(output_end - output_start) / (input_end - input_start)}
M950 S1 C"io4.out"  ; assign GPIO port 1 to heater4 on expansion connector, servo mode
global InputStart = 0 
global InputEnd = 1
global OutputStart = 0
global OutputEnd = 90
global ScaleFactor = (global.OutputEnd - global.OutputStart) / (global.InputEnd - global.InputStart) ; no need for the math in this instance but it makes it clear how you arrive at the value.
global ServoOut = floor(global.ScaleFactor * (fans[0].actualValue - global.InputStart) + 0.5) + global.OutputStart ; calculate position required on sevo - use floor() to apply rounding
M280 P1 S{global.ServoOut} ; adjust valve position to reflect fan speed.

and deamon.g

set global.ServoOut = floor((global.ScaleFactor * (fans[0].actualValue - global.InputStart)) + 0.5) + global.OutputStart ; calculate position required - use floor() to apply rounding to nearest whole number
;echo {global.ServoOut}
M280 P1 S{global.ServoOut} ; adjust valve attached to servo on P1 to reflect scaled fan speed.

-Max

OwenD

@maxgyver
Try removing all the spaces around the variable names and in the equations
I'm pretty sure I read another post where that was an issue on SBC
There is also a 3.3RC1+2 binary you might try.

Also note that daemon.g only runs once every 10 seconds now, so there's going to be a delay between setting the fan and the servo reacting.
Moot until you get it working again of course.

MaxGyver

@owend said in Pressured air cooling controlled with servo and ball valve:

Also note that daemon.g only runs once every 10 seconds now, so there's going to be a delay between setting the fan and the servo reacting.

I recon this would make this solution almost useless considering the motion of the servo itself introduces another small delay.

I will submit a Firmware Feature request to add Stepper/RC-Servo Support for M106

-Max

dc42

@jay_s_uk said in Pressured air cooling controlled with servo and ball valve:

@MaxGyver can you not use the L and X commands of M106 to do that?

Lnnn Set the minimum fan speed (0 to 255 or 0.0 to 1.0) when a non-zero fan speed is requested.
Xnnn Set the maximum fan speed (0 to 255 or 0.0 to 1.0) when a non-zero fan speed is requested. (supported in RRF >= 2.02)

Yes that should work.

MaxGyver

@dc42

I have already tried using the L and X factor of M106 as suggested by @Phaedrux and @jay_s_uk in this thread.

@maxgyver said in Pressured air cooling controlled with servo and ball valve:

@Phaedrux

I have already tried this. The L and X factor of M106 will not scale the range but rather set the minimum and maximum fan speed.

With this configuration the valve will stay in the same slightly open position at a fans peed of 5-80%. So I still only have real control over the flow from 80-90% fan speed.

I did play around with different values for L and X again just yesterday without success.
To my understanding the L and X factor only define the start and endpoint of the usable range between S=0-255.
But in order to work with a servo I need to scale every point in between S=0-90 (0°-90° servo angle) to have linear control. Or am I missing something here?

-Max

OwenD

@maxgyver
I guess as a work around (for print files) you could use a post processing script in your slicer to replace all M106 to a macro
So if you replace M106 S125 with
M98 P"0:/macros/valve control.g" S125
Then in your macro do all your math and set valve
You can get the speeds using param(S)
e.g
Var Speed=param(S)