This seems to defeat the purpose of previous_millis_cmd, preventing the
time elapsed from previous_millis_cmd from ever reaching
max_inactive_time or stepper_inactive_time while the heat was on.
Fixes a bug in the Extruder Runout Prevention feature that caused the
extruder to move back to “current_position” after a move if it was
activated while the move was in progress. For long home moves (which
are longer than the dimensions of the machine’s working area), this
would cause the machine to crash into the far end of its travel after
homing. This usually occurred on the Z axis, which could result in
damage to the machine if you don’t hit the reset button in time.
This allows PID_FUNCTIONAL_RANGE to use a maximum duty cycle higher
than PID_MAX. This is useful for powerful heaters to heat quickly in
bang-bang mode, but use a lower duty cycle that is easier to stabilize
in PID mode.
whosawhatsis