Assign end stop as temp sensor and fan output as heater



  • I read that it is possible to assign a fan output as a heater output but how do one know what frequency to use? I would assume it would require using an external mosfet to handle the load as well.

    Is it possible to assign endstop as additional temp sensor? I have a duex5 and duet 2.



  • Endstops are on/off devices, temperature sensors are analog devices.Completely different animals .... so no
    Yes you could run a fan output to drive an SSR if you so desired.
    SSR's run well at 10 Hz but if I was using a fan output I would probably configure it as an on/off (bang-bang) kind of device. Others might have a better handle on this though.
    Edit: Thinking about this some more ... you want to control the heater with pwm, the frequency is a side effect (having difficulty expressing myself). I really can't see how this could be done through the fan port ... but then there are some clever people here so who knows



  • @jens55

    then what solution is there if I need additional temperature sensors for a thermistor?



  • Can't really help with that but if you have maxed out the Duet2 and Duex5 combo, I think your next step would be to go with a Duet3 setup. Again though, I have no knowledge in that area.



  • @jens55 darn it. I was thinking maybe the next step was getting a pt100 daughterboard.



  • I am not sure how the daughter boards fit into things. Somebody else will need to chime in.



  • As per documentation, pt100 duaghterboard should work fine, on Duet as well as on Duex. Of course you need pt100 sensor with it.



  • @aidar said in Assign end stop as temp sensor and fan output as heater:

    As per documentation, pt100 duaghterboard should work fine, on Duet as well as on Duex. Of course you need pt100 sensor with it.

    Yes, I did read that it will require the pt100 sensor. Not a problem.


  • administrators

    @jens55 said in Assign end stop as temp sensor and fan output as heater:

    Endstops are on/off devices, temperature sensors are analog devices.Completely different animals .... so no
    Yes you could run a fan output to drive an SSR if you so desired.
    SSR's run well at 10 Hz but if I was using a fan output I would probably configure it as an on/off (bang-bang) kind of device. Others might have a better handle on this though.
    Edit: Thinking about this some more ... you want to control the heater with pwm, the frequency is a side effect (having difficulty expressing myself). I really can't see how this could be done through the fan port ... but then there are some clever people here so who knows

    SSRs work OK at low PWM frequencies, e.g. 10Hz for a bed or chamber heater.



  • @dc42 yes. A chamber or bed heater was the original purpose.

    David, can you confirm if there is no other way to get additional temp sensor before I need to purchase a pt100 daughterboard and a pt100 sensor?



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  • administrators

    @tekstyle said in Assign end stop as temp sensor and fan output as heater:

    @dc42 yes. A chamber or bed heater was the original purpose.

    David, can you confirm if there is no other way to get additional temp sensor before I need to purchase a pt100 daughterboard and a pt100 sensor?

    Are you already using all 3 thermistor inputs on the Duet, and all 5 on the Duex5?

    You can possibly use the Z probe input as a thermistor input (I haven't tested it), but you would need to add an external reference resistor.



  • @dc42 said in Assign end stop as temp sensor and fan output as heater:

    @tekstyle said in Assign end stop as temp sensor and fan output as heater:

    @dc42 yes. A chamber or bed heater was the original purpose.

    David, can you confirm if there is no other way to get additional temp sensor before I need to purchase a pt100 daughterboard and a pt100 sensor?

    Are you already using all 3 thermistor inputs on the Duet, and all 5 on the Duex5?

    You can possibly use the Z probe input as a thermistor input (I haven't tested it), but you would need to add an external reference resistor.

    I am using all 3 thermistors and 5 on the duex5. I am using a zprobe as well for z min. I believe the zprobe-mod pin is unused at the moment.


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