Always ON fan pins for ON/OFF DC use

giostark

Hi there ,
I'm trying to find a way to command the external resistor of the glass (a resistor placed on the perimeter of the circular glass). I need a DC current from the board that come activated just during the print. (must not be intermittent). This current will activate an SSR and it will let pass the current from the external (secondary) power supply to the glass resistor.
I need a continuous current because in the circuit of this resistor I have also a potentiometer and a thermometer for regulate the power released to the resistor. Those tools don't like a fast ON/OFF as the thermistor 12V is used to give. (so I can't use the 12v nozzle signal)

Are the pins of the always ON fans actionable just when the print start and stopped at the end of it? If yes , how to code the config.g?
I see the term always ON what it means , but I have seen that is possible to free those pins for other purpose... so maybe what I need is possible.
https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans
I could use the fan PWM signal of the nozzle but would be nice to have a dedicated connector (that now is unused).

Thanks

fcwilt

@giostark

I think it is safe to assume that the always on fan outputs are just that, always on.

Frederick

dc42

@giostark always on means exactly that. I suggest you create a daemon.g file that monitors the printer state and turns an output on when the state is Printing, and off at most other times. You will need to choose whether to have the output on or off when the state is Paused.

giostark

@dc42
I think that I'll go to use the nozzle fan signal. I'll fork it till the SSR. I need that the glass is hot before the print start but that go off when the print finish. The better solution seems the nozzle fan. I can set the minimum temp activation of the fan at ex 60 degree and leave the glass come hot. Then rise the nozzle temp and start the print. And vice versa when the print is finished and the nozzle temp is again at 60 degree the external resistor will go off.
Seems a good way to solve the need.
Thanks anyway for the suggestion !
I'll open other 3ds where I'll show the working mess I have done on the glass

fcwilt

@giostark

Could you not use the bed heater output? It sounds like you are heating the bed.

Frederick

giostark

@fcwilt TNX Frederick
I thought that but the signal is intermittent. And the cascade SSR+potentiometer+thermometer doesn't like a fast intermittent. I think that inside the potentiometer there is a slow component that need a continuous current.
I have to open 2 3ds , one for the external resistor of the circular glass and the second for the enclosure (that work pretty good now!).

fcwilt

@giostark said in Always ON fan pins for ON/OFF DC use:

@fcwilt TNX Frederick
I thought that but the signal is intermittent. And the cascade SSR+potentiometer+thermometer doesn't like a fast intermittent. I think that inside the potentiometer there is a slow component that need a continuous current.
I have to open 2 3ds , one for the external resistor of the circular glass and the second for the enclosure (that work pretty good now!).

I don't think the signal has to be intermittent. A PWM signal of 100% should be always on.

I'm not sure how you would configure the output for just on or off but I think it may be possible - @dc42 would know for sure.

Frederick