Node for multiple outputs based on single input

[877]

Could anyone recommend a node for controlling a fan based on a numeric range please?

The incoming number is from an air quality sensor, the output is a hepa filter fan.

I'd like to ensure there's not a "bouncing" effect, i.e.:
Sensor detects >500, turns fan to LOW, sensor drops to <500, fan goes OFF, sensor detects >500.......and so on...

So I think a switch might be problematic.

I'll also make it so if the LWT is offline, the fan runs at LOW speed, in case the sensor fails.

[Colin]

node-red-contrib-hysteresis should do what you want.
Or you can easily achieve the same thing in a function node.

[Colin]

@877

I'll also make it so if the LWT is offline

For this insert a Switch node that only passes the message if Offline, then a Change node that sets the fan speed to low and then feed that to the fan.

[877]

I did think of the word hysteresis but wasn’t sure it was the correct term, thanks for the link to the node.

I’m very interested in the function node code,
I can understand filtering for the range but not sure how it could handle the hysteresis type issue.

[Colin]

Looking more carefully I see you want three threshold values, so you would have to use three hysteresis nodes.
Here is a flow using a function node for one threshold. You could use three of those, or extend the code to include all three thresholds.

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[Tany]

Working on PWM controlled TRV-valves and -ventilationFans. Temp & hum are collected via MQTT or Zigbee, and handled with function node to convert into 0-10 or 0-255. This goes to a filter node that only outputs RBE on changes, and payload to MQTT/Zigbee out.
For non-Zigbee, the (remote) fan is controlled by a ESP32 + PLC-LM358-PWM2V PWM to Voltage (0-10V).
For Zigbee, the PWM is messaged to a Zigbee-bridge, that controls the TRV/Fan
For this config i expect no hystereris-node or ranges needed.
As the sensor-reading is approaching the target, fans will slow down and TRVs gradually will close. For TRV... the CV/pump need to go OFF before reaching end point.
Cheers,
T