I have a problem where the software sets the temp of the hot-end to about 10 degrees C below the target the g-code specifies. This is consistent when set to low or high temps. This is an image of a temp plot from octoprint.
I know the hardware is good because the head heats up to the wrong temp with a normal heating curve. The printer had no problems with the same firmware for weeks. This just started happening today.
I have tried ...
1) Using the front panel to test temp instead of g-code
2) Changing temperatures
3) Trying different PIDS including the auto-tuned ones
4) Rebooting printer between each test
5) reading the marlin configuration.h looking for clues
Anyone have any idea what might cause this?