Need help with configuration of temp. mapping

[mosal1]

Hi all, not sure what I am doing wrong.
I configured fanpico as standalone controller in my homelab server rack.
It is powered from external source through mbfan1 connection.
I have connected two fans to fan1 and fan5, both configured to use power from mbfan1.
Both fans are intake fans.
I am using both sensors to drive fans with different configurations.

My config is :
conf:fan1:name Top Fan
conf:fan5:name Bottom Fan
CONF:FAN1:SOURCE SENSOR,1
CONF:FAN5:SOURCE SENSOR,2
CONF:SENSOR1:TEMPMAP 25,0,40,100
CONF:SENSOR2:TEMPMAP 26,0,35,100

All looks fine but I expected fans to be stopped when temperature is below thresholds.

I was expecting that fans will stop when temperature is below 25 or 26 for the fans.
I can see PWM is 0 for the fans but they are still running with about 500 rpms...

As per readout below bottom fan should be stopped as temperature is below 26, PWM is 0, but it is still running:

fan1,"Top Fan",488,16.26,0.9
fan5,"Bottom Fan",503,16.77,0.0
sensor1,"Top sensor",25.1,0.9
sensor2,"Bottom sensor",23.7,0.0

What I am doing wrong?

Thank you in advance for the help.

Details on the config (I omitted irrelevant parts) and output from the sensors is below:

sys:ver?
FanPico-0804D v1.7.6 (Jul 11 2025; Release; SDK v2.1.1; pico_w)

conf?
Current Configuration:
{
"id": "fanpico-config-v1",
"debug": 0,
"log_level": 3,
"syslog_level": 3,
"local_echo": false,
"led_mode": 0,
"spi_active": 0,
"serial_active": 1,
"onewire_active": 0,
"i2c_speed": 1000000,
"adc_vref": 3,
"display_type": "default",
"display_theme": "default",
"display_logo": "default",
"name": "fanpico1",
….,
"fans": [{
"id": 0,
"name": "Top Fan",
"min_pwm": 0,
"max_pwm": 100,
"pwm_coefficient": 1,
"source_type": "sensor",
"source_id": 0,
"pwm_map": [[0, 0], [100, 100]],
"filter": {
"name": "none"
},
"rpm_mode": "tacho",
"rpm_factor": 2,
"lra_low": 1000,
"lra_high": 0,
"tach_hyst": 1,
"pwm_hyst": 1
},
….
{
"id": 4,
"name": "Bottom Fan",
"min_pwm": 0,
"max_pwm": 100,
"pwm_coefficient": 1,
"source_type": "sensor",
"source_id": 1,
"pwm_map": [[0, 0], [100, 100]],
"filter": {
"name": "none"
},
"rpm_mode": "tacho",
"rpm_factor": 2,
"lra_low": 1000,
"lra_high": 0,
"tach_hyst": 1,
"pwm_hyst": 1
},…
"sensors": [{
"id": 0,
"name": "Top sensor",
"sensor_type": 1,
"temp_offset": 0,
"temp_coefficient": 1,
"temp_map": [[25, 0], [40, 100]],
"temperature_nominal": 25,
"thermistor_nominal": 10000,
"beta_coefficient": 3950,
"filter": {
"name": "none"
}
}, {
"id": 1,
"name": "Bottom sensor",
"sensor_type": 1,
"temp_offset": 0,
"temp_coefficient": 1,
"temp_map": [[26, 0], [35, 100]],
"temperature_nominal": 25,
"thermistor_nominal": 10000,
"beta_coefficient": 3950,
"filter": {
"name": "none"
}
}….
read?
mbfan1,"POWER",490,16.34,0.0
mbfan2,"mbfan2",0,0.00,0.0
mbfan3,"mbfan3",0,0.00,0.0
mbfan4,"mbfan4",0,0.00,0.0
fan1,"Top Fan",488,16.26,0.9
fan2,"fan2",0,0.00,0.0
fan3,"fan3",0,0.00,0.0
fan4,"fan4",0,0.00,0.0
fan5,"Bottom Fan",503,16.77,0.0
fan6,"fan6",0,0.00,0.0
fan7,"fan7",0,0.00,0.0
fan8,"fan8",0,0.00,0.0
sensor1,"Top sensor",25.1,0.9
sensor2,"Bottom sensor",23.7,0.0
sensor3,"pico_temp",31.6,38.8
vsensor1,"vsensor1",0.0,0.0
vsensor2,"vsensor2",0.0,0.0
vsensor3,"vsensor3",0.0,0.0
vsensor4,"vsensor4",0.0,0.0
vsensor5,"vsensor5",0.0,0.0
vsensor6,"vsensor6",0.0,0.0
vsensor7,"vsensor7",0.0,0.0
vsensor8,"vsensor8",0.0,0.0

[tjko]

Not all "PC" fans stop when PWM signal goes down to 0% duty cycle. I think Intel specification refers these as "Type A" fans, in my experience most fans behave like this:

Some fans (like most Noctua ones) do stop when duty cycle goes to 0. What make/model fans are you using?

[mosal1]

Thank you for quick response.
I did not think about this at all.
Before I decided to use fanpico I was using cheap PWM controller from aliexpress with the same fans.
With that controller fans stop spinning when temperature dropped below treshhold.
I am using Thermaltake CT200 fans and it looks they are type A fans according to AI.
So that cheap PWM controller probably also cut power to the fan when temp was below treshold.

I assume fanpico can not achieve the same with new firmware changes - to cut the power to the fans when temp is below treshold?

[tjko]

Currently there is no (hardware) support to switch power off to individual fans. That would require a new board design which incorporates necessary components to switch power on demand, etc...

However, I recall that there are less "expensive" fans than Noctua ones that support stopping fan using 0% PWM signal. I think Arctic has fans that have this feature. I think Arctic calls this feature "0dB Mode".

[mosal1]

Hey, thank you for explanation.
It makes sense, I just did not expect this behaviour from past experience.
My idea was to stop fans when they are not needed to minimise dust on filters, i will just need to clean dust filters more frequently.

I checked Noctua AF20 and also these seems to run at min PWM.
It is not an issue at all.