Siemens SINUMERIK 840D sl Function Manual page 431

Local position of gear unit/encoder
Figure 2-4
Motor/load gear
The motor/load gear supported by SINUMERIK is configured via the following machine data:
MD31060 $MA_DRIVE_AX_RATIO_NUMERA (Numerator load gearbox)
MD31050 $MA_DRIVE_AX_RATIO_DENOM (Denominator load gearbox)
The transmission ratio is obtained from the numerator/denominator ratio of both machine
data. The associated parameter sets are used automatically as default by the control to
synchronize the position controller with the relevant transmission ratios.
Since a gear stage change is not always carried out automatically, and there are also
several ways to request a gear stage change, the position controller is not always
incorporated via parameter sets.
Note
For more information about parameter sets during gear stage change, see:
References:
/FB1/ Function Manual, Basic Functions; Spindles (S1).
Basic logic functions: Velocities, Setpoint/Actual Value Systems, Closed-Loop Control (G2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
Gear unit types and encoder locations
Detailed description
2.3 Setpoint /actual-value system
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