Siemens SINAMICS S120 Function Manual page 97

Encoder types for two-encoder systems
With a two-encoder system, the required redundancy can also be achieved using less highly
qualified encoders. In this case, therefore, encoders with a microprocessor in the signal path
can also be used. Each encoder output signal must also supply sin/cos signals of 1 Vpp on
the incremental channels A/B.
In addition to the permissible motors with integrated encoder with a DRIVE-CLiQ connection,
in principle, encoders that can be connected to the following Sensor Modules can be used
for safe actual value acquisition:
● SMC20
● SME20/SME25
● SME120/SME125
Note
Also for a two-encoder system, motors with integrated resolver with DRIVE-CLiQ connection
have not been enabled for Safety Integrated.
Actual value synchronization
Figure 5-14
The mean value of the actual values of both encoders is calculated cyclically after actual
value synchronization (p9301.3 = p9501.3 = 1) was activated. The maximum slip defined in
p9349/p9549 is monitored within the crosswise comparison clock cycle (r9724). If "actual
value synchronization" is not enabled, the value parameterized in p9342/p9542 is used as
tolerance value for the crosswise comparison.
Safety Integrated
Function Manual, (FHS), 11/2009, 6SL3097-4AR00-0BP0
Example diagram of actual value synchronization
Safety Integrated Extended Functions
5.12 Safe actual value acquisition
97