Siemens SINUMERIK 840Di Function Manual page 1519

Possible positioning from Phase 1c:
The spindle rotates at the programmed spindle speed,
when the speed is lower than the speed entered in machine data:
MD35300 $MA_SPIND_POSCTRL_VELO (position-control activation speed).
The spindle is synchronized.
Phase 2
Spindle speed > Position-control activation speed
The command SPOS, M19 or SPOSA starts deceleration of the spindle with the acceleration
stored in machine data:
MD35200 $MA_GEAR_STEP_SPEEDCTL_ACCEL
until it reaches the position-control activation speed.
When the speed drops below the encoder limit frequency, the spindle is synchronized.
Spindle speed < Position-control activation speed
When SPOS, M19 or SPOSA is programmed, the spindle switches to position control mode
(if it is not yet in position control mode).
MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL (acceleration in position control mode)
is activated. The travel path to the end 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, the operational sequences in phases
2 - 3 - 4 - 5, or -2 - 4a - 5a are executed.
Phase 3
Spindle speed > Position-control activation speed
When the position-control activation speed stored in machine data:
MD35300 $MA_SPIND_POSCTRL_VELO
is reached:
• Position control is activated (if not already active)
• The distance-to-go (to end point) is calculated
• Acceleration in machine data:
Spindle speed < Position-control activation speed
To reach the end point, the spindle is accelerated up to the speed defined in machine data:
MD35300 $MA_SPIND_POSCTRL_VELO (position-control activation speed).
This is not exceeded.
The braking start point calculation identifies when the programmed spindle position can be
approached accurately at the acceleration defined in machine data:
MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL.
Spindles (S1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
MD35210 $MA_GEAR_STEP_POSCTRL_ACCEL (Acceleration in position control mode)
is activated (or this level of acceleration is maintained)
Detailed Description
2.1 Spindle modes
2-15