Siemens SINUMERIK 840D Function Manual page 748

S1: Spindles
18.2 Operating modes
MD35300 $MA_SPIND_POSCTRL_VELO
The spindle is synchronized.
Phase 2
Spindle speed > Position-control activation speed
When the SPOS, M19 or SPOSA command is activated, the spindle begins to slow down to the
position-control activation speed with the configured acceleration:
MD35200 $MA_GEAR_STEP_SPEEDCTL_ACCEL
The spindle is synchronized once the encoder limit frequency threshold is crossed.
Spindle speed < Position-control activation speed
SPOS, M19 or SPOSA are programmed to switch the spindle to position control mode (if it is not
already in that mode).
The configured acceleration in position control mode is activated:
MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL
The travel path to the target point is calculated.
The spindle travels to the programmed end point optimally in terms of time. This means that the
end point is approached at the highest possible speed (maximum MD35300
$MA_SPIND_POSCTRL_VELO). Depending on the appropriate secondary conditions, phases
2 - 3 - 4 - 5 or 4a - 5a are executed.
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
748
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA