Water Pump Low RPM when using Tach and PWM

RogerPodacter

I installed a new liquid cooling pump 4 wire Freezemod to replace my old water pump. When i connect only 12v and ground the pump operates normally with the expected flowrate. But when i add the tach and signal wire, the pump flowrate reduces to about 50% flowrate.

here is the config i am using:
config.g

M950 F5 C"out4+out4.tach" Q25000 ;Q500                   ; create fan 4 for Water Cooling 12V Fan 4 on pin out4 and set its frequency
M106 P5 C"Liquid Cooling Pump" L0.0 X1.0 S0 H4 T15 ;T20        ; set fan 4 name and value. Thermostatic control turned on for liquid cooling hotend
;M106 P5 C"Liquid Cooling Pump" S0 H4 T20        ; set fan 4 name and value. Thermostatic control turned on for liquid cooling hotend

DWC registers 2200 RPM which is the nominal RPM. but something just doesnt seem right. i reveresed the PWM and tach wire just to make sure, but i get no output, so i think i have the wires correctly identified.

Side question is it ok to connect tach and signal with the board already powered up or is there a risk of damage? i shut down the printer each time i test the wiring but it would be convenient to be able to test the signal and tach in real time without a bootup. but i dont want to short something.

Here is the pump on Amazon.
https://www.amazon.com/dp/B07TZJH7VD?psc=1&ref=ppx_yo2ov_dt_b_product_details

RogerPodacter

@RogerPodacter ok i solved my issue, i forgot to invert the PWM signal. this code fixed the pump and now runs at full speed.

M950 F5 C"!out4+out4.tach" Q25000 ;Q500                   ; create fan 4 for Water Cooling 12V Fan 4 on pin out4 and set its frequency
M106 P5 C"Liquid Cooling Pump" L0.0 X1.0 S0 H4 T15 ;T20        ; set fan 4 name and value. Thermostatic control turned on for liquid cooling hotend
;M106 P5 C"Liquid Cooling Pump" S0 H4 T20        ; set fan 4 name and value. Thermostatic control turned on for liquid cooling hotend

RogerPodacter

@RogerPodacter my issue is solved with normal pump performance, but i just realized that the RPM reported in DWC is double what i am expecting. its a 2200 RPM pump but its displayed ~4100 RPM. what could i be doing wrong to cause this?

OwenD

@RogerPodacter
The link you posted shows a max RPM of 800?

Looking at the code, it appears that RRF expects two pulses per revolution.
You link doesn't give details of how many pulses it outputs per rev, but I suspect it's not two.
My own pump (different unit) is currently displaying about 1400 rpm.
I've always just taken that on face value and monitor it in daemon.g