pwm controlled waterpump

cosmowave

Hello

i'd like to install a pwm controlled waterpump. The pump is a Laing DDC-Pump 12V DDC 3.2 PWM.
The pump has 2 connectors. One for the power supply (+12VDC, GND) and another with the PWM input and tacho signal.

How do i have to connect this pump to my Duet2Ethernet?
Can i use exp.heater3 output for the PWM signal? (i allready use heater0-2)
I've read in the doc that this output is on 3.3V level. Is that directly usable for the "PWM pump control"? Or do i need something like an "amplifier" or "level shifter"?

Which input will be best to read the tacho signal? Can there be a problem with the voltage?

thanks in advance

o_lampe

@cosmowave
The tacho signal will be your biggest problem, if you want to use it as closed-loop feedback.
Duet2 isn't capable to read fast signals from external sources.
You could probably use it as a sign of life signal or attach an external RPM meter?

OwenD

@cosmowave
Not sure if it's the same type of pump but on my duet wifi I have this setup

;water pump
M950 F1 C"!fan1+^exp.pb6" Q25000                             ; create fan 1 (water pump) on inverted pin fan1 and set its frequency.  Set RPM to E3 stop with pullup enabled
M106 P1 C"Water Pump" H1 L0.5 X1 B1.2  T50:60                       ; set fan 1 name and value. Thermostatic control is turned on.  Monitoring hotend sensor

; water temp monitor & fan
M950 F2 C"!fan2+^exp.e3_stop" Q25000                                        ; create fan 2 on pin fan2 and set its frequency
M308 S5 P"e1temp" Y"thermistor" A"Water temp" T10000 B3950  					; Configure Water temp sensor
M106 P2 C"Radiator Fan" H5 L0 X1 B1.2  T33:38    	; set fan 4 value, turn on at 30% if the water temperature reaches 30C, and increase to full speed gradually as the temperature rises to 40C

dc42

@cosmowave most likely the pump takes a standard open drain PWM input. In which case you can connect it as you would connect a 4-wire fan. However, as it draws about 1.7A, you can't power it from the internal 12V supply of a Duet 3 or Duet 3 Mini assuming you are using 24V VIN. So you will need an external buck regulator to provide 12V.

cosmowave

Thanks for your answers.
@o_lampe
It will be ok as a "sign of live" signal. Closed-loop control is not really necessary
I will also try an external flow-meter and temp sensor. But again, also for checking if flow is present.

@dc42
I d'like to power (+12VDC,GND) the pump directly from my 12V power supply.
Only the pwm and tacho signal goes to the duet.

OwenD

@cosmowave
Definitely a different pump to me but similar idea.
I use this
https://www.aliexpress.com/item/4000034575710.html
I power mine from an external 12v supply as the duet is on 24v.
DWC looks like his

I monitor the pump in daemon.g

cosmowave

@owend Yes, it's not the same pump. I use this one:
WaterPump

Has your pump also a pwm control input?

OwenD

@cosmowave said in pwm controlled waterpump:

Has your pump also a pwm control input?

Yes it does.
Essentially I treat it as a thermostatically controlled fan.
Same with the radiator fan.
In my case the radiator fan doesn't ever turn off completely as it has a minimum possible PWM (didn't realise till I got it).

EDIT
I should note that the indicated speed is the impeller speed.
If a hose blew, it would still show as running. I need to put a flow sensor on the return near the radiator as well.

cosmowave

@dc42 said in pwm controlled waterpump:

However, as it draws about 1.7A, you can't power it from the internal 12V supply

Is it possible to power the pump from the bed heater output?
I use a SSR (3-32VDC in) for my bed.
Is it possible to set the bed heater output constantly on, without linking to a temp sensor?

Phaedrux

@cosmowave said in pwm controlled waterpump:

Is it possible to set the bed heater output constantly on, without linking to a temp sensor?

You can invert the pin name with a ! to have it on by default.

cosmowave

@Phaedrux
oh yes. That's easy!
Thanks

cosmowave

@phaedrux said in pwm controlled waterpump:

You can invert the pin name with a ! to have it on by default.

But is it possible to create the (bed) heater, which i'd like to use for powering my water pump (always on), without linking it to a temp sensor?
With M950, the T parameter seems not to be optional...

Phaedrux

Well you can link it to any temp sensor you like with any temp range you like. So in effect any sensor could allow it to be enabled or disabled.

I suppose you could define it as a GPIO pin to control the water pump with an M42 command instead of as a heater, then it's just on or off.

o_lampe

@cosmowave
Maybe define it as a spindle? That way you don't need a temp sensor and can set RPM directly. (as percentage of max RPM)

cosmowave

@o_lampe But is "spindle on/off" M3 / M5 not CNC/laser specific ? Can i use the commands in printer mode?

tecno

@cosmowave said in pwm controlled waterpump:

@o_lampe But is "spindle on/off" M3 / M5 not CNC/laser specific ? Can i use the commands in printer mode?

Why do you need to PWM control this cooling unit? I use similar as @OwenD SSR to switch on the pump. Always ON

M950 F1 C"out6" Q500  	; create fan 1 on pin out6 and set its frequency  Hotend Cooling Waterpump
M106 P1 S1

cosmowave

@tecno I'd like the idea to control the speed of the pump... also for reliability.