Siemens Sinamics S120 Function Manual page 343

Tolerance window (p2722)
After switching on, the difference between the stored position and the actual position is
ascertained and, depending on the result, the following is initiated:
Difference within the tolerance window -> the position is reproduced based on the current
actual encoder value.
Difference outside the tolerance window -> an appropriate fault (F07449) is output.
The tolerance window is preset to quarter of the encoder range and can be changed.
The position can only be reproduced if, in the powered-down state, the encoder was moved
through less than half of the range that it can represent. For the standard EQN1325
encoder, this is 2048 revolutions or half a revolution for singleturn encoders.
Note
The ratio stamped on the gear rating plate is often just a rounded-off value (e.g.1:7.34). If, for
a rotary axis, it is not permissible to have any long-term drift, then the actual ratio of the
gearbox teeth must be requested from the gearbox manufacturer.
Multiple drive data sets
Position tracking of the load gear can be activated in multiple drive data sets.
● The load gear is DDS-dependent.
● Load gear position tracking is computed only for the active drive data set and is EDS-
● The position tracking memory is only available once for each EDS.
● For position tracking to be continued in different drive data sets under the same
● When the changeover between drive data sets involves a change in gear unit, the
● With identical mechanical conditions and encoder data set, a DDS changeover does not
Drive functions
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
CAUTION
dependent.
mechanical conditions and with the same encoder data sets, it must be activated
explicitly in all the relevant drive data sets. Possible applications of drive data set
changeover with continuation of position tracking:
– Star/delta changeover
– Different ramp-up times / controller settings
position tracking function starts from the beginning again, i.e. it behaves on changeover
as if a POWER ON had occurred.
affect the status of the encoder adjustment or reference point.
Function modules
7.7 Closed-loop position control
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