Warning Light for Bed temp



  • Hi.
    I would like to have a physical warning light to indicate the bed is still hot, ie over say 35 /40 degrees.
    I have 24v LEDs to indicate that the bed and hotend is 'On' but would like a way to show that the bed is still hot, is this possible?
    I have asbestos fingers but someone else might not!
    Thanks in advance. BTW i have a Maestro.



  • Use a fan output and link it to the bed as you would a fan for cooling the hotend.
    E.g. M106 P2 T35 H0



  • @paulhew As fans can be configured to run thermostatically, then one way would be to connect an LED to spare fan connector and map this to the bed heater. So something like M106 Pn S255 I0 F250 H0 T40 should work. Where "n" is the number of the fan connector. H0 is the bed heater. T40 is the temperature at which the "fan" would come on, in this case 40 deg C.

    Or if you wanted, you could vary the brightness of the LED by using something like T35:60 with maybe a low threshold of like L125. That would light the LED at 50% when the temperature is 35 deg C or above, rising to 100% at 60 deg C and above. You'd need to play around with those values.

    EDIT. I was typing my response at the same time as others so didn't see their answers.



  • I belive you can use fan2 pins for that, of course assuming they are not in use already. Configure it as thermostatically controlled fan monitoring bed heater.
    https://duet3d.dozuki.com/Wiki/Gcode#Section_M106_Fan_On



  • Thanks to @aidar @deckingman and @jay_s_uk

    I am using all of my fan outputs, P2 is used for the case cooling fan, P1 for hotend and P0 for part cooling.
    I do have a spare heater output (E1) which I was going to use for LEDs, could I use that?
    I thought one of the spare pins I have like on the expansion header or somewhere else could be used.
    Thanks again.



  • @paulhew You can use the hotend too.

    The A parameter can be used to assign a fan to a different output pin, for example a spare heater output (use a M307 command to disable the heater and free up the pin first).

    From the info for M106 from the wiki.
    Is your case cooling fan always on? If so, switch that to one of the always on fan outputs.



  • So I have issued the following command to disable the heater2, my spare heater port.
    M307 H2 A-1 C-1 D-1

    When I send the next command I get this
    M42 P3 S0
    Error: M42: Logical pin 3 is not available for writing

    Obviouly I am doing something wrong, I am not a GCode wizard!
    This board is a Duet Maestro


  • administrators

    @paulhew said in Warning Light for Bed temp:

    M42 P3 S0
    Error: M42: Logical pin 3 is not available for writing

    P3 is Heater 3. Use P2 in that M42 command.



  • @dc42 Thank You David.
    Doh! LED now works.
    I was going to write a line like this which I use for my can fan control
    M106 P2 T25:65 L128 H100:101:102 ;Case fan temp control

    So
    M106 P2 T35:100 H0
    But I can already see the issue in regards to the P2. Can I map the logical pin2 to a new fan number, so I can use P3 in that line?
    Or am I going about this the wrong way?



  • 80C thermal normaly open (at room temp) switch. No software involvement needed.



  • @doctrucker said in Warning Light for Bed temp:

    80C thermal normaly open (at room temp) switch. No software involvement needed.

    Sorry, I do not understand.
    I would like the lamp to be lit if the bed is still hot, I have a glass bed and it takes a while to cool and I do not always have DWC open, hence by using code so it can read the temp and light the LED if conditions are met.



  • Search for KSD-01F and you'll find lots of cheap chinesium parts that will work, just pick a temperature and a normally open (NO) part.

    Run the lamp in series with the bimetallic switch attached to the bed, it will only conduct if above its marked temperature. It will work with the only requirement being that power supply is on.



  • Hi @paulhew. @bearer beat me to it.

    In a nutshell it's the reverse of a kettle bimetallic switch, but self resets.

    It closes once the switch hits a certain temperature and opens once it cools below that temp give or take a little hysteresis. Commonly used as a really simple fan controller.


  • administrators

    @paulhew said in Warning Light for Bed temp:

    But I can already see the issue in regards to the P2. Can I map the logical pin2 to a new fan number, so I can use P3 in that line?

    Yes, you can use:

    M106 P3 A2

    then fan 3 will be mapped to heater 2 output.



  • @dc42 said in Warning Light for Bed temp:

    M106 P3 A2

    Thanks DC.
    After disabling H2 again, even though it is in my config.g, I tested to make sure the LED illuminates which it does, then issued your string.
    M106 P3 A2
    Error: M106: Fan number 3 is invalid, must be between 0 and 2

    Should it work with a Duest Maestro?

    P.


  • administrators

    @paulhew said in Warning Light for Bed temp:

    @dc42 said in Warning Light for Bed temp:

    M106 P3 A2

    Thanks DC.
    After disabling H2 again, even though it is in my config.g, I tested to make sure the LED illuminates which it does, then issued your string.
    M106 P3 A2
    Error: M106: Fan number 3 is invalid, must be between 0 and 2

    Should it work with a Duest Maestro?

    P.

    Good point, the Maestro is limited to 3 fans in RRF 2. The RRF3 early beta for the Maestro supports 4 fans, but the way you setup the pin mapping is different. See https://forum.duet3d.com/post/91906 if you want to try it.



  • Thanks David.
    I could move one of my fans, like the case fan.
    I was going to ask in the rrf3 forum, but can I take a decent ssd card, format it and drop rrf3 on it an keep my original card and swap if need be?
    Thanks again David and all, it is appreciated.
    Ask me a network question or something about model helicopters and I could help back!


  • administrators

    @paulhew, a copy of your existing config should work except as described at https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview.



  • @paulhew said in Warning Light for Bed temp:

    Thanks David.
    I could move one of my fans, like the case fan.
    I was going to ask in the rrf3 forum, but can I take a decent ssd card, format it and drop rrf3 on it an keep my original card and swap if need be?
    Thanks again David and all, it is appreciated.
    Ask me a network question or something about model helicopters and I could help back!

    The firmware doesn't reside on the SD card itself, rather, the bin file for the firmware is written onto the board itself, so to swap between firmwares you would need to reflash each time.


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