Siemens SINAMICS S120 Commissioning Manual page 241

Parameterizing encoder selection for position control
An encoder is assigned to the position control during commissioning. This encoder setting is
shown in a drop-down list at the top right in the "Mechanical system" screen form. You can
change the encoder assignment in this screen form before parameterizing the position control.
The following options are available:
1. Select the required encoder in the "Encoder system" (p2502) drop-down list.
– No encoder
– Encoder 1
– Encoder 2
– Encoder 3
2. Enter the motor revolutions for the gear ratio between the motor shaft and load shaft in the
"Number of motor revolutions" (p2504) field.
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 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.
Commissioning with Startdrive
Commissioning Manual, 06/2020, 6SL3097-5AA10-0BP2
5.7 Basic parameterization of the drive objects
Commissioning
239