Siemens SINUMERIK 828D Function Manual page 1269

Phase 3
Spindle speed > Position-control activation speed
When the configured position-control activation speed (MD35300 $MA_SPIND_POSCTRL_VELO) is reached:
• Position control is activated (if not already active).
• The distance­to­go (to the target point) is calculated.
• There is a switch to the configured configured acceleration in position control mode (or this acceleration is
retained):
MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL
Spindle speed < Position-control activation speed
The spindle was accelerated up to the configured position-control activation speed (MD35300
$MA_SPIND_POSCTRL_VELO) to reach the end point. This is not exceeded.
The braking start point calculation detects when the programmed spindle position can be approached accurately
at the acceleration configured in position control mode (MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL).
Phase 4
Spindle speed > Position-control activation speed
The spindle brakes from the calculated "braking point" with machine data:
MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL
to the target position.
Spindle speed < Position-control activation speed
At the time identified by the braking start point calculation in phase 3, the spindle brakes to a standstill with the
acceleration configured in position control mode (MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL).
Phase 4a:
When the SPOS command is activated the proximity of the end point is such that the spindle can no longer be
accelerated to the configured position-control activation speed (MD35300 $MA_SPIND_POSCTRL_VELO).
The spindle brakes to a standstill with the acceleration configured in position control mode
(MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL).
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
S1: Spindles
16.2 Operating modes
1269