Summary: If a gcode file is truncated, Taz will stop wherever it was, and keep the heaters on.
I created a gcode file using slic3r and used slic3r to save the file directly to an SD card.
I properly ejected the SD card using the software before removing it from the card reader. (note this is on Linux Mint 18.2).
I put the card into the Taz and printed from SD.
The print started fine, and was still running fine 4 hours after I started it, and I went to bed. I woke up at 3:00 AM and checked the print. I found the printhead stopped on the object with a small puddle of molten plastic under the tip. The % complete indicator was missing, but the print time was still incrementing. I was able to go into the menu, move the head off the print, extrude a bit more plastic to make sure the nozzle was not carbonized shut, then turn of the heaters.
I found later that the gcode file was about 600 k shorter than it should have been, and the end gcode was missing.
- The Taz could scan the gcode before starting to verify that it ends with the print head temperature set to zero, and if not generate a warning message requiring the user to acknowledge the situation before continuing.
- If the Taz reaches the end of the file with the heaters still on, it could turn them off.
I like my hardware to fail safe. This was not a safe fail.