Siemens SINUMERIK 840D Function Manual page 747

Procedure
Figure 18-1
Note
The speed arising from the configuration of the encoder limit frequency for the
resynchronization of the encoder (MD36302 $MA_ENC_FREQ_LOW) must be greater than
the position-control activation speed (MD35300 $MA_SPIND_POSCTRL_VELO).
Phase 1
Positioning from phase 1a:
The spindle is rotating at a higher speed than the encoder limit frequency. The spindle is not
synchronized.
Positioning from phase 1b:
The spindle is rotating at a lower speed than the encoder limit frequency. The spindle is
synchronized.
Note
If the position control is active, the speed can only amount to 90% of the maximum speed of the
spindle or the encoder limit frequency (10% control reserve required).
Positioning from phase 1c:
The spindle rotates at the programmed spindle speed whereby the speed is lower than the
configured position-control activation speed:
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
Positioning from rotation
S1: Spindles
18.2 Operating modes
747