AJAX timeout error during a print



  • Hi
    I am using wifi firmware 1.15c and web interface 1.12 and keep getting timeouts when the machine is idle and when printing.
    It appears random.
    I just reconnect again and the print progress is up to date, so it's not a big problem, just frustrating, after all it shouldn't happen.
    This is the error :-
    Communication Error

    An AJAX error has been reported, so the current session has been terminated.

    Please check if your printer is still on and try to connect again.

    Error reason: timeout

    What can I do to provide more information?



  • I've had lots of these too. I'm running windows 10 and using chrome. It doesn't cause any trouble I just hit reconnect but it is happening every 10-15 minutes.


  • administrators

    Can both of you confirm that the error reason given is always timeout, and that you are running DWC 1.12?



  • Firmware Version: 1.15c (2016-09-05)
    WiFi Server Version: 1.02
    Web Interface Version: 1.12

    Communication Error

    An AJAX error has been reported, so the current session has been terminated.

    Please check if your printer is still on and try to connect again.

    Error reason: timeout



  • Yes the reason is always timeout and I am using DWC1.12



  • I have only used Chrome for windows 10 so far. I will try other browsers as I read in another thread it might be the browser ending the session.


  • administrators

    I suspect it's caused by an unreliable WiFi connection, for example due to temporary interference. I've asked chrishamm if he can change DWC to do a configurable number of retries instead of just one.



  • For what it's worth I have yet to experience this with my Duet WiFi. I use both Chrome and Firefox on Linux…no issues at all.

    On the other hand, with my Duet 0.6-which is obviously wired- I receive the AJAX timeout error like clockwork. It's not running the latest firmware though and I can't recall off hand what version it is...maybe 1.12 I believe...



  • @dc42:

    I suspect it's caused by an unreliable WiFi connection, for example due to temporary interference. I've asked chrishamm if he can change DWC to do a configurable number of retries instead of just one.

    I have a pre-production duet wifi board.
    Nothing else is on my network wirelessly so any hints as to what could be causing interference?



  • @dc42:

    I suspect it's caused by an unreliable WiFi connection, for example due to temporary interference. I've asked chrishamm if he can change DWC to do a configurable number of retries instead of just one.

    I have a pre-production duet wifi board.
    Nothing else is on my network wirelessly so any hints as to what could be causing interference?



  • I think the ESP8266 is limited to 2.4GHz which can get really crowded these days. It may be nothing particular to your network but rather any number of wireless devices in your vicinity that share the same RF spectrum.

    Most wireless routers or access points give you ability to manually choose a particular "channel" to use, you may want to try arbitrarily changing that to a few different ones and see if that makes a difference.



  • @W3DRK I'll look into that, thanks for the info


  • administrators

    I am on my phone right now so can't check but I thought the latest version of DWC has the ability to set the number of AJAX timeout retries…



  • Yes you are right, I've just set it to 3 so I will see how that performs.



  • In regards to the WIFI channel selection, there are free programs available that detect and list all SSIDs in range, their strength, and the channel they are broadcasting on. This is really useful information for selecting a channel to use for your own SSID.

    Microwave ovens can disturb wifi signals at 2.4Ghz. As can wireless landline telephones.



  • I'll try independently testing the increase retries for dwc (how do I set this?) and installing a WiFi access point in the room near to the printer.



  • Definitely fewer disconnects with a router in the room with the printer in it, on a clear channel and fairly close by.



  • Switched to Chrome Canary and had even fewer but still maybe 2 today in about 3-4 hours. This is not really a problem. Still unsure why these are happening though.



  • also for me i get a lot of timeouts.

    it dose seem to be when its trying to do something, like download a file or during printing.

    some times when i go to the G code tab it starts lagging and will not display stuff, or just time out.

    I think part of this is the connection for me ( but I'm not sure of that yet) , but i though i would post for more feed back!

    ~Russ


  • administrators

    FWIW the WiFi received signal strength is reported to the USB port when you enable WiFi. This might help diagnose connection issues. I'll make it easier to retrieve this information in a future firmware release.



  • I improved mine a lot but I've got a router 4 feet away from it. I imagine the environment immediately near to a 3d printer is not the best in terms of EMI.

    Is it possible to have an external wifi antenna, in a future revision? Or the port for one if its needed?


  • administrators

    We'd love to use an external antenna, and we produced a few pre-production boards with them. There are two issues that prevent us from making it standard:

    1. The ESP8266 versions supporting external antenna are not FCC certified. I have read that it is impossible to get a wifi module with external antenna certified, you have to get the entire piece of equipment certified instead.

    2. The version of the ESP8266 with external antenna is the ESP-08, but that has only 512kbytes or 1Mbyte flash memory, compared to the 4Mbyte flash on the ESP12F that we use. Currently we could manage with 1Mbyte, but it would limit the possibilities for firmware expansion. For the prototypes we changed the flash chip on the ESP-08, but this is not practical to do in production.


  • administrators

    We might be able to supply a boards with no esp mounted from the next production run… If you then choose to mount an esp7 or 8 then that's fine. Changing the flash chip is fiddly but doable if you have a rework station.



  • I think it would be neat if the ESP's could be setup to run the web interface in a manor similar to OctoPrint so it could be used on various other controllers over a serial connection…


  • administrators

    @W3DRK:

    I think it would be neat if the ESP's could be setup to run the web interface in a manor similar to OctoPrint so it could be used on various other controllers over a serial connection…

    It's already been done and there is a thread on the reprap.org forums about how to do it. But the file upload speed to SD card is very slow. I put a lot of effort into the Duet WiFi design and firmware into getting a good file upload speed, because I know that it matters to users.


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