Controlling Filament Dryer with DHT22

taylo708

I have created a filament dryer heater that I need to run 24/7. I also would like to drive this heater off of humidity but from reading on here it doesn't look like I can do that. I currently don't use a heated bed as I let the heated chamber heat the bed up. So I have mapped the extra heater with M140 and using the temperature from the DHT22. Does anyone know of a better way to control this? Is it possible to control it by humidity? Thank you

Phaedrux

You can do quite a bit with conditional gcode and the object model.

https://docs.duet3d.com/en/User_manual/Reference/Gcode_meta_commands

OwenD

@taylo708
Have you seen this guide?

https://docs.duet3d.com/en/User_manual/Connecting_hardware/Temperature_connecting_DHT

taylo708

@owend I sure have, it is a nice guide that tells you how to connect a DHT22 sensor.

OwenD

@taylo708
I was assuming you were not getting the humidity readings from the sensor.
If you have the sensor set up to display the humidity then you can use daemon.g to control the heater.
I'd imaging you'd need to set up several global variables in config.g including one to ensure you can turn the heater on/off

global ChamberHeaterOn = false
global lowHumidity = 25
global midHumidity = 50
global highHumidity = 75

Then in daemon.g use something like this (change the sensor value)

if global.ChamberHeaterOn = false
    M140 S-273.1 ; switch off heater
elif  sensors.analog[2].lastReading <= global lowHumidity
    M140 S40
elif  sensors.analog[2].lastReading <= global midHumidity
    M140 S60
elif  sensors.analog[2].lastReading <= global highHumidity
    M140 S80
else
    ; whatever you want to do if over the high value

And set up a couple of buttons to set the global to true or false to offer manual control when needed