Siemens SINAMICS S120 Function Manual page 845

If encoder 1 (p0187) is changed over via DDS, then an MDS must also be changed over.
Note
Switching over between several encoders
In order to be able to switch between two or several encoders using the EDS switchover
function, you must connect these encoders via various Sensor Modules or DRIVE-CLiQ
ports.
When using the same connection for several encoders, the same EDS and the same
encoder type must be used. In this case a switchover on the analog side (e.g. of the SMC) is
recommended. A switchover on the DRIVE-CLiQ side is, due to the permissible insertion
cycles and the longer times to establish DRIVE-CLiQ communication, only possible with
some restrictions.
If a motor is operated at one time with motor encoder 1 and the other time with motor
encoder 2, then two different MDSs must be created with identical motor data.
One drive object can manage up to 16 encoder data sets. The number of encoder data sets
configured is specified in p0140.
When a drive data set is selected, the assigned encoder data sets are also selected.
Note
EDS in the Safety mode
The encoders that are used for Safety functions must not be changed when the data set is
switched over. The Safety functionality checks the safety-relevant encoder data after a data
set switchover: If a change is detected, fault F01670 is displayed with a fault value of 10,
which results in a non-acknowledgeable STOP A.
The safety-relevant encoder data in the various data sets must therefore be identical.
Drive functions
Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
Basic information about the drive system
12.2 Data sets
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