Heater without creating a Tool



  • I am using a Duet Wifi running RepRapFirmware so control a prototype machine that i am developing. The material processing side of the machine requires external heaters and temperature probes. They are JUST a heater and temperature sensor that i want to control. The only way that i can see to do this right now is to assign the heater and probe to a tool and just not define a drive so it acts just a like a standard heater. Is there a way that i am missing to have control over a heater without having to define each as a tool?



  • There is a "chamber heater" that you could assign to be that heater and sensor, unless you are already using it. However, that would only provide one channel of heating/sensing.
    https://duet3d.com/wiki/Connecting_and_configuring_a_chamber_heater

    How does it behave when you simply ignore assigning a motor drive with a tool?



  • It seems to work fine but the problem is that you can only have an active tool and making one active makes every other tool into "Standby"

    Id just love the ability to add JUST a heater. Tell it what heater channel to use, what thermistor/PT100 input and just have a plain heater.



  • You can do that but I'm not sure how of the top of my head search for posts by Deckingman as he has that sort of thing set up AFAIK I mean that is how chamber heaters work


  • administrators

    Is there any reason why you can't just add them as additional heaters for the tool(s) you use?

    If that's not possible, then perhaps one solution would be for the firmware to support multiple 'chamber heaters'.


  • administrators

    Its a more general firmware wishlist thing for me but I would love the ability to chain together any thermistor with any heater and use G10 Snnn to set the temperature. It would not matter if the tool was in standby because the standby temperature would be maintained.



  • @Dougal1957:

    You can do that but I'm not sure how of the top of my head search for posts by Deckingman as he has that sort of thing set up AFAIK I mean that is how chamber heaters work

    In my case, I have a number of thermistors attached at various points around the printer (mostly on stepper motors and driver chips), which I use as "virtual heaters". I then use fans in thermostatic mode which are switched on/off by these thermistors. I wouldn't have thought that it would be too difficult to use the fan output on the Duet board with a suitable interface (MOSFET or SSR or some such) with inverted logic to switch on a heater instead of a fan.

    So for example, one of he thermistors is stuck the the Z axis stepper motor is defined thus:
    M305 P104 X3 S"Z Stepper" T100000 B3950 R4700; Set thermistor + ADC parameters

    Then the fan that blows onto the motor is defined thus:
    M106 P3 S127 I0 F500 H104 T40; Set fan 3 (Z Stepper fan) to work thermostatically on P104 virtual temp

    So using the above example, I'd have thought that one could use the fan3 output to switch something that will supply the necessary current to drive a heater. You'd also need to invert the logic so that when the trigger temperature is reached, the heater turns off rather than the fan turning on. Electronics isn't my strong point but with a relay, this would simply be to use normally open contacts but you probably wouldn't want to use a mechanical relay.



  • Ian can I ask if you can clarify something since you seem very much into using multiple temp channels. Or anyone else?

    I am trying to use e0 thermistor to monitor my water cooling block I'm fitting to my hotend. The heaterblock of said hotend now has a pt100 via a daughter board so e0 thermistor channel should be free to be used for something else, but is it? Or is it intrinsically linked to heater 1 (1st hotend)?

    When you define virtual channel 104 in the example above does that refer to actual thermistor 4 on the duetx5? How does the firmware know which actual thermistor to use as a virtual heater? Is it by numbering 100=0,101=1 etc?


  • administrators

    timmit99, if there is just one extra heater then configure it as a chamber heater as has been suggested to you already.

    For a future release (probably for just the Duet WiFi and Ethernet) we are looking at supporting multiple bed and chamber heaters, so you could control any number of extra heaters by pretending they are additional chamber heaters.


  • administrators

    @DjDemonD:

    Ian can I ask if you can clarify something since you seem very much into using multiple temp channels. Or anyone else?

    I am trying to use e0 thermistor to monitor my water cooling block I'm fitting to my hotend. The heaterblock of said hotend now has a pt100 via a daughter board so e0 thermistor channel should be free to be used for something else, but is it? Or is it intrinsically linked to heater 1 (1st hotend)?

    When you define virtual channel 104 in the example above does that refer to actual thermistor 4 on the duetx5? How does the firmware know which actual thermistor to use as a virtual heater? Is it by numbering 100=0,101=1 etc?

    Temperature sensors are assigned to virtual heaters using the X parameter in the M305 command for the virtual heater, just as for real heaters. So use X1 to use the E0 thermistor input.



  • Thanks thats very helpful.


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