Noctua fan rpm's same all the time

[matej1006]

Hello

i have 3 noctua fans for cooling my water. and when i want check RPM is same all the time, no matter if fans are 100% or just on 30%. RPM is 1500.

i add diode and remove it try all sort of things with out succes.

and at the same time how can i connect this flow meter to measure if there is a flow of water colling and how high is?

[dc42]

@matej1006 as far as I can tell from your photo, they are 3-wire fans. To get correct RPM readings when you PWM a fan, you need to use a 4-wire fan (which has a separate PWM control input). The tacho on a 3-wire fan will only give the correct reading when the PWM is 100%.

[matej1006]

@dc42 on picture you see only water flow sensor which i would like to connect to duet2 eth too see if my head water colling is working and what is flow.

for noctua fan's i have this one's:
https://noctua.at/en/nf-f12-industrialppc-3000-pwm

and i add zener diode back still nothing different

Here is part of code for Noctua fan's

;Water temp
M308 S5 P"e0temp" Y"thermistor" T10000 B10000 A"Water temp."                  ;configure sensor 5 as thermistor on pin e1temp
                                                         
; Water colling NOCTUA FAN'S
M950 F1 C"!duex.fan7+exp.pb6" Q30000 							; fan 0 is a 4-wire PWM fan so invert it, use high PWM frequency, tacho connected to PB6 on expansion connector
M106 P1 H5 I1 T20:25 L125                                       ; set fan 0 value. Thermostatic control is turned on

; Water colling PUMP
M950 F2 C"!Fan0" Q30000 										; fan 2 is a 4-wire PWM fan so invert it, use high PWM frequency, tacho connected to PB6 on expansion connector
M106 P2 H5 I1 T20:25 L255                                       ; set fan 2 value. Thermostatic control is turned on

[dc42]

@matej1006 please show how you connected the fan(s) to the Duet.

You can only read one tacho through a single pin such as exp.pb6.

[matej1006]

@dc42
Like that i have connected nuctua fans eith my duet/12v dc external supply

So then i can't have two tacho readings on duet2 ?
1 for noctua rpm and 1 for water cooling flow

[dc42]

@matej1006 you can have multiple tacho readings on Duet 2 running RRF3 if you have suitable input pins to connect them to. The reason we suggest exo.pb6 is that it is available even if you have a DueX expansion board connected. If you don't have a DueX expansion board then you can use the five additional endstop inputs on the expansion connector for tacho inputs. For safety, connect them with a diode in series as we suggest for exp.pb6.

[matej1006]

@dc42 So then i can use on duex5 one of the e_stop 3 4 5 6 for tacho reading?