"Function Error" is a calculated value and is made by the
Function generator.
The Function Generator inputs are values like P_SOLL, V_SOLL and A_SOLL.
If the motor is running in position mode with a certain torque
and suddenly the needed torque to make the motor move with
the specified velocity is increasing and it reaches the Torque value
( Reg. 7 ) which is the limitation of the torque, the speed will drop to
a value where the specified torque is enough. Maybe the motor stop.
The function generator will, as soon as the Torque value is reached,
decrease the expectation of the position, and the difference between
the original expected positioning curve and the new, is giving some
counts which is described as "Function error".
This register can be used for testing if the motor has been hold back
for too long.
Remember to reset this register before next move. Otherwise it's only reset after "Motor Reset".