Can't stay connected after adding heated bed?

  • I installed my heated bed this weekend and everything works as it should, but now I just keep getting chain disconnected from the web browser. I googled the error and was seeing suggestions of upgrading the firmware, but I think I'm already upgraded?

    Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
    Firmware Electronics: Duet WiFi 1.02 or later + DueX2
    Firmware Version: 1.21 (2018-03-21)
    WiFi Server Version: 1.21RC4(08b3)
    Web Interface Version: 1.21-RC4

    The error in question:

    "A communication error was reported, so the current session has been terminated."

    Any ideas?

  • administrators

    Is the Duet installed underneath the heated bed? If so then the bed heater element may be shielding the Duet's WiFi antenna from the WiFi signal from your router.

  • administrators

    @kskiff7034 two things to check:

    1. Is the Duet resetting (use M122 command when you reconnect using the browser). That could imply that the power supply is drooping very badly when the heated bed is coming on. It would have to be a very large droop to cause the Duet to reset though.

    2. is the heated bed causing interference that is causing the Duet to disconnect. Se if the issue is changed when the the bed is not heating.



  • administrators

    @t3p3tony or as david says!

  • The box is underneath the heated bed, but it's a fairly large printer (~450mm on the z axis) so I can't imagine it's shielding it. Is there something specific in the heated bed that would cause this?

    It resets just fine. The heated bed is run off main power so if I understand correctly it doesn't use the limited power from the power supply.

  • Moderator

    It's a fairly small and weak antenna and needs to be in the clear to send and receive properly. I can definitely see how a heated bed blocking it with all it's electrical wiring and high current could cause interference.

  • I can understand interference, but what kind of distances are we talking in order to avoid said interference? I'll inevitably have to extend a ton of wires move it out from underneath so I'd like to get it right the first time.

  • Moderator

    It's going to depend. Perhaps you can post a photo of your current setup so we can gauge better if interference is likely.

    If you run M122 you can find out the strength of the wireless signal currently.

    I also notice that you're running release candidates of the wifi server and web interface. It may be worth upgrading those to full releases to see if you get any improvement in connection stability.

  • administrators

    The bed heater element will act as a WiFi shield. If the Duet WiFi is mounted underneath the bed (which is a common arrangement for delta printers) then the WiFi antenna should protrude from an opening at the side. To see how I do it on my delta, see

  • My arrangement is nothing like that. I'll try to grab a picture this afternoon, but the bed is almost 2 feet above the electronics board.

  • Disregard the mess.

  • administrators

    It's hard to make out the Duet in your photo. I suggest:

    • Keep the wiring clear of the WiFi antenna
    • If possible, mount the Duet with the wifi antenna well clear of the aluminium frame, and preferably vertical instead of horizontal
    • Use the M122 command to check the WiFi signal strength with the Duet in various locations and various orientations

  • Moderator

    @kskiff7034 said in Can't stay connected after adding heated bed?:

    Disregard the mess.

    That looks like a Dbot. I mounted the duet along the right bottom side rather than directly underneath. Added benefit of having it vertical. Though in your case it's hard to say if it would make a difference as the bed is quite high above it. What are you getting for signal strength? Can you bring the router in the same room and see if it still drops out? If it still drops than maybe you have some wiring issues?
    1_1534232404760_10725654-E722-4DE2-B73E-5D8ABB2F9249.jpeg 0_1534232404759_54A1F36F-C085-47F9-9171-382FE5402EDC.jpeg

  • It began as a D-Bot, but there's so many changes it's hard to call it a D-Bot at this point.

    The problem seems to come and go. I just ordered a bunch of wire and am going to dive into the arduous task of re-doing all the wiring from scratch and cleaning everything up. If the problem persists I'll get some more details and try to dive further in.

  • Moderator

    @kskiff7034 said in Can't stay connected after adding heated bed?:

    It began as a D-Bot, but there's so many changes it's hard to call it a D-Bot at this point.

    I think that's the story of most DBots. It's a good starting platform for customization.

    Good luck with the wiring. My suggestion is to do everything right the first time, because once it's in there you will loathe to take it all down again to redo something. Ask me how I know.

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