print suddenly stopped due to a gcode/firmware issue?

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sprior
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Joined: Thu Apr 10, 2014 8:37 pm

print suddenly stopped due to a gcode/firmware issue?

Post by sprior » Thu Jun 05, 2014 5:26 am

I was in the middle of printing something and the print suddenly stopped for no apparent reason. I use a Raspberry Pi running Octoprint to control the printer, but it's not obvious whether it's the gcode, Octoprint, or firmware to blame. Here's the log, any ideas?

Send: N6429 G1 X41.025 Y245.824 E3.5575*85
Recv: ok
Send: M105
Recv: ok
Send: N6430 G1 X41.857 Y246.406 E3.6066*91
Recv: ok
Send: N6431 G1 X53.331 Y234.932 E4.3909*95
Recv: Error:No Checksum with line number, Last Line:6428
Recv: Resend:6429
Send: N6429 G1 X41.025 Y245.824 E3.5575*85
Recv: ok
Recv: Error:Line Number is not Last Line Number+1, Last Line:6428
Recv: Resend:6429
Send: N6429 G1 X41.025 Y245.824 E3.5575*85
Recv: ok
Recv: ok
Send: N6430 G1 X41.857 Y246.406 E3.6066*91
Recv: Error:Line Number is not Last Line Number+1, Last Line:6429
Recv: Resend:6430
Send: N6430 G1 X41.857 Y246.406 E3.6066*91
Recv: ok
Recv: ok
Send: N6431 G1 X53.331 Y234.932 E4.3909*95
Recv: Error:Line Number is not Last Line Number+1, Last Line:6430
Recv: Resend:6431
Send: N6431 G1 X53.331 Y234.932 E4.3909*95
Recv: ok
Recv: ok
Send: M105
Recv: Error:Line Number is not Last Line Number+1, Last Line:6431
Recv: Resend:6432
Changing monitoring state from 'Printing' to 'Error: Printer requested li...'
Recv: ok

sprior
Posts: 381
Joined: Thu Apr 10, 2014 8:37 pm

Re: print suddenly stopped due to a gcode/firmware issue?

Post by sprior » Thu Jun 05, 2014 5:42 am

I looked at the incomplete print carefully and around one hole there is a bump of plastic sticking more than a layer height over the rest of the print. Could the nozzle have crashed into that bump and caused a fault that the Marlin firmware picked up which resulted in the aborted print?

sprior
Posts: 381
Joined: Thu Apr 10, 2014 8:37 pm

Re: print suddenly stopped due to a gcode/firmware issue?

Post by sprior » Thu Jun 05, 2014 5:56 am

Here's a pic of the area that seemed to be printing when the firmware got out of sync with the host. You can see the raised circle and compare it to the layer height which you can see in the small lower area to the left of the hole. I was using a 50% infill.
Attachments
2014-06-05 00.29.23.jpg
2014-06-05 00.29.23.jpg (176.86 KiB) Viewed 4795 times

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ednisley
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Re: print suddenly stopped due to a gcode/firmware issue?

Post by ednisley » Thu Jun 05, 2014 2:11 pm

sprior wrote: Send: N6429 G1 X41.025 Y245.824 E3.5575*85
Recv: ok
Send: M105
Recv: ok
Send: N6430 G1 X41.857 Y246.406 E3.6066*91
Recv: ok
Send: N6431 G1 X53.331 Y234.932 E4.3909*95
Recv: Error:No Checksum with line number, Last Line:6428
Recv: Resend:6429
Send: N6429 G1 X41.025 Y245.824 E3.5575*85
There's a bare M105 in the middle and Marlin points out that it doesn't have a proper checksum: each line should end with a *xx checksum value. Because the "Send" line shows the bare M105, the fault lies upstream of the firmware, which is kvetching about receiving the wrong thing.

The "ok" response indicates that Marlin has received the command and put it into the processing queue, not that the command is perfect. The error happens when Marlin parses the command and figures out what to do with it.

M105 = "Read current temperature", so it probably came from the Octoprint routine that monitors the printer temperatures. That happens a lot, so why this particular command doesn't have a sequence number or checksum isn't at all obvious.

Because the recovery back-and-forth doesn't include the M105, Octoprint doesn't seem to know about it. That's odd.
sprior wrote:Could the nozzle have crashed into that bump and caused a fault that the Marlin firmware picked up
There's no feedback from printing operations.

Feedback loops stabilize the extruder & platform temperatures, but everything else runs open-loop: the firmware has no idea what's going on out there between the nozzle and the platform. Folks have added filament tension / break monitors, tweaked the limit switches, and suchlike, but the firmware remains blissfully unaware of most mechanical problems.

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jimc
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Re: print suddenly stopped due to a gcode/firmware issue?

Post by jimc » Thu Jun 05, 2014 2:25 pm

regarding the blob, that occurred from when the nozzle sat there in one place. your looking at the ooze all collected there in one spot. that is pretty common when you nozzle comes to a decent length stop on top of a print. the blob wasnt the cause, it was the result.

sprior
Posts: 381
Joined: Thu Apr 10, 2014 8:37 pm

Re: print suddenly stopped due to a gcode/firmware issue?

Post by sprior » Thu Jun 05, 2014 3:32 pm

Thanks both, I'll follow up with the OctoPrint dev.

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