Siemens SINAMICS S120 Getting Started page 161

3. Enter the load revolutions for the gear ratio between the motor shaft and load shaft in the
"Number of load revolutions" (p2505) field.
4. Enter the neutral length unit LU per load revolution in the "LU per load revolution" (p2506)
field.
5. Interconnect the "Modulo correction activation" (p2577) signal source for the activation of
the modulo correction.
6. Correct the default value for axes with modulo correction in the "Modulo correction
modulo range" (p2576) field.
Parameterizing the load gearbox position tracking
If you have parameterized encoder 1 for the position control, you can set the position
tracking as follows:
1. Activate the "Activate load gearbox position tracking" (p2729.0) option.
2. Activate the desired axis type (p2720.1).
By default, the "Rotary axis" axis type is active.
3. If required, correct the number of resolvable revolutions for a rotary absolute encoder in
the "Virtual revolutions" (p2721) field.
4. If required, correct the value for the tolerance window for the position tracking in the
"Position tracking tolerance window" (p2722) field. The value is specified in whole
encoder pulses.
Examples of LU configurations
The unit LU per load revolution is a free dimension, independent of SI units, for the position
control of an EPOS axis.
The LU per load revolution upper limit is limited by the encoder resolution (rXXXX). A value
above this limit can be selected, but then not all set positions can be approached because
they may be between two encoder lines. This could result in an unsmooth axis.
The LU per load revolution should be selected as high as possible. In this way, a better
dynamic response can be achieved. If the values for p2506 are too low, this can result in
jumps when speed precontrol is activated.
For good repeat accuracy, the LU per load revolution should be selected in the ratio of 1:10
to the encoder resolution, if the encoder resolution can provide this at the required dynamic
response.
Example 1: Linear axis – spindle (encoder on the motor side)
Leadscrew pitch = 10 mm
Gear ratio i = 1 (p2505/p2504)
Target variable to be controlled: mm
Encoder resolution = 15,000 LU
Getting Started, 12/2018, 6SL3097-5AG30-0BP0
Performing basic parameterization
6.3 Drive axes
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