Hotend and Heatbed turned off, printer kept moving
I walked out of my office for about 15 minutes while printing something. When I came back in the printer was moving the extruder around as if it was printing, but no filament was coming out. I assumed it was just a jam (even though thinking back now, I didn't see the filament moving or hear clicking like a usual jam). So I stopped the print and looked at the display to see that the hotend and heatbed were already less than half of what they were supposed to be set at. Checking Octoprint it shows they both turned off about 10 minutes before I walked in to see what was going on. Has anyone had this happen before? I was printing from the SD card, but have Octoprint running to keep an eye on it while I'm not sitting in the room.
Re: Hotend and Heatbed turned off, printer kept moving
I sat and watched the printer this time. I generated a new gcode file and started printing it from the SD card again. I noticed it pause for about 2 seconds on two different occasions. Then it moved and asked for a filament change. I reloaded the filament and disabled the filament sensor so I didn't get another false positive. When I disabled the sensor the printer paused for a moment and then continued. After a few seconds I noticed it started under extruding. I looked at the temperatures and both the bed and hotend were off, but the printer just kept on moving. I quickly clicked through and selected the Preheat => PETG option and it kept going fine. Manually pausing the printer and resuming does not cause the heaters to turn off. I have no idea what is going on.
Re: Hotend and Heatbed turned off, printer kept moving
That's odd. The Preheat option shouldn't appear while printing--it should be replaced with the Tune option. It almost seems like the printer is getting put into a state where it thinks that the print has stopped (hence the reason the cooldown process starts and Tune gets replaced with Preheat) but it continues reading Gcode from the card.
First of all, make sure that you're on the latest firmware--3.2.0. Now try unplugging it from your OctoPrint system and running the print again from SD to do a little sanity check. If that works, try plugging it back in and initiating a print from OctoPrint (not the SD card) to make sure that USB serial communications are solid. If both of those succeed and your normal approach continues to consistently fail, I'm thinking it may be a firmware bug.
Re: Hotend and Heatbed turned off, printer kept moving
I've had a similar problem for the last week (one day after I built my machine). In my case at least I think I've found the problem. Didn't spot your thread until after I'd started a new one here though:
https://shop.prusa3d.com/forum/hardware-firmware-and-software-help-f64/heaters-disabled-power-panic-sense-fault--t18422.html#p85764
Re: Hotend and Heatbed turned off, printer kept moving
I found a thread on the GitHub page for the latest firmware with people having similar problems. I did a full power off for a few minutes and completely disconnect OctoPrint before printing again. It completed a 6 hour print. I have never actually printed from OctoPrint, but instead initiated prints already on the SD card. Both of my failures this time were started from the SD card using the printer's menu, but OctoPrint was still connected. For now I'll probably just leave OctoPrint disconnected while people smarter than me do some more troubleshooting. The only thing that worries me is that one of the errors occurred when the filament sensor triggered a false alarm (shiny filament).