Slowdown issue



  • I have a reliability issue with my duet wifi/duex setup. Occationally and in the middle of a print the printer slows down dramatically executing a couple of cm of moves then pauses for several seconds. Even when I pause the print movement to homne is really slow. Other functions are also slow, web interface is barely responsive. Jog controls on the panel due are unresponsive or extremely slow.

    Obviously this slowdown causes a failed print.

    The only remedy is to reboot, cold or warm reset does not matter.
    This is on 1.19

    VIdeos and picture: https://photos.app.goo.gl/6nvOED4R3x1qW2hi2


  • administrators

    Thanks for your report. I have one other report of similar occurrences, this time on a Duet Ethernet. To help me track this down:

    1. Can you confirm that movements happen at normal speed, it's just that there are long pauses between them?

    2. After you pause the print, is the printer slow to respond to jog commands too?

    3. After pausing the print, please try sending M552 S-1 to disable the wifi module. Then, with the wifi module disabled, see if it prints at normal speed.

    4. Also please connect YAT or Pronterface via USB (NOT Repetier Host), send M115 via USB to confirm the connection, and see if any debug messages are displayed when it is trying to print.

    5. Also send M122 from USB and post the diagnostic report here.



  • I can confirm 1 and 2
    I'll do 3-5 once I can reproduce



  • Interesting, I just had this happen during my homing sequence a couple of days ago. After homing X then Y (sensorless), the move to the back/center of the bed for z probing was excruciatingly slow, like 5% of what it should be. I reset the printer and carried on and chalked it up as some random glitch. Reprinting the same file went fine.



  • From the reply I gather you suspect some interrupt storm/high traffic density from the wifi module. I do have access to a MSO scope so if there any test point relevant to the issue I might try to monitor them (If it works out logistically)


  • administrators

    Thanks. Under normal conditions, with the machine idle I expect to see nothing on pin 22 of the WiFi module (the pin should be at about +3.3V), and a burst about 35us long every approx. 150us on pin 5.



  • I have had this happen to me as well. At first I thought it was a fluke but now it has shown up a few times and caused a failed print after 16 hours of printing on a 24 hour print.

    I've uploaded what I was able to glean from the serial port (using Repetier, sorry) in the link below. I cannot get my machine to reset the wifi module so that i can connect the web client.

    https://www.dropbox.com/s/orf3hjdboa6m7xu/Duet%20Printing%20Slow.txt?dl=0

    IIRC I've been seeing this after pausing during a print. The strange thing about this occurence is that the machine ran fine and paused as it should when the filament trigger went off. After refilling, the machine ran fine for at least a few hours before getting stuck in this slow state. During that time nobody touched the machine. I don't think a filament trigger occurred as there is plenty left and I have tried wiggling the filament (the trigger is using a micro switch) to make sure it wouldn't cause a false positive.

    Here is a section of the event log when the filament ran out:
    2018-01-21 00:29:10 Extruder 3 reports no filament
    2018-01-21 00:29:17 Printing paused

    2018-01-21 10:20:11 Error retrieving WiFi status message - I had to reset the wifi module which is something I have to do frequently
    2018-01-21 10:20:11 Wifi module is idlei3SkunkWorks, IP address 10.0.0.115
    2018-01-21 10:20:17 Wifi module is connected to access point i3SkunkWorks, IP address 10.0.0.115
    2018-01-21 10:20:18 HTTP client 10.0.0.112 login succeeded
    2018-01-21 10:34:27 Printing resumed - after I reloaded filament
    2018-01-22 08:50:47 Wifi module is idle

    If this is related to the WiFi and would not happen on the Ethernet, then I would buy an Ethernet as the WiFi module has always been problematic for me.


  • administrators

    Don't use Repetier Host, if you are not careful then it enables all debug output (as seen in your Dropbox link), which is itself enough to make the printer go slow.


  • administrators

    To those who have experienced this issue:

    1. Which Duet are you using?

    2. Do you also have a DueX2 or DueX5 connected?

    3. Which firmware version(s) were you using when the problem occurred?



  • @dc42:

    To those who have experienced this issue:

    1. Which Duet are you using?

    2. Do you also have a DueX2 or DueX5 connected?

    3. Which firmware version(s) were you using when the problem occurred?

    1. Duet WiFi

    2. Yes, X5

    3. 1.20



  • @dc42:

    To those who have experienced this issue:

    1. Which Duet are you using?

    2. Do you also have a DueX2 or DueX5 connected?

    3. Which firmware version(s) were you using when the problem occurred?

    1: Duet Wifi
    2: Yes, duex5
    3: 1.19



  • I have a relay that switches a 120V solenoid on my machine. This is usually switched on and off at the start and end of prints. I noticed that the problem would occur right after the solenoid was switched on and often times after a print finished and switched the solenoid off but if I canceled a print which doesn't switch the solenoid off the problem didn't happen. I tried putting a ferrite on one of the 120V leads and that seems to have improved or fixed the problem. Is this just a placebo or is it possible that EMI could be causing this?


  • administrators

    Yes, it's entirely possible that an electrical transient or EMI is putting the hardware in a state that is triggering the problem. One possibility is that it is affecting the I2C interface between the Duet and the DueX.

    Is there a flyback diode in parallel with the relay coil, and a snubber network either in parallel with the solenoid or in parallel with the relay contacts?



  • @dc42:

    Yes, it's entirely possible that an electrical transient or EMI is putting the hardware in a state that is triggering the problem. One possibility is that it is affecting the I2C interface between the Duet and the DueX.

    Is there a flyback diode in parallel with the relay coil, and a snubber network either in parallel with the solenoid or in parallel with the relay contacts?

    No, I do not have one. I could switch it to an SSR if that would be better and not require extra hardware. Are there any off the shelf solutions for diodes/snubbers, preferably DIN rail mounted? That would be a good option, I just don't have time to make one from scratch.


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