Safe Actual Value Acquisition - Siemens SINAMICS S120 Function Manual

Safety Integrated Extended Functions

5.12 Safe actual value acquisition

5.12 Safe actual value acquisition
Supported encoder systems
The Safety functions used to monitor motion (e.g. SS1, SS2, SOS, SLS and SSM) require
safe actual value acquisition.
For safe speed/position sensing...
● Single-encoder systems or
● Two-encoder systems
...can be used.
Single-encoder system
In a single-encoder system, only the motor encoder is used to safely acquire the drive actual
values. This motor encoder must be appropriately qualified (see encoder types). The safety-
relevant actual values are generated either directly in the encoder or in the Sensor Module
and are transferred to the Control Unit by way of fail-safe communication via DRIVE-CLiQ.
For motors without a DRIVE-CLiQ interface, the connection is established by means of
additional Sensor Modules (SMC or SME).
Even if the drive is operating in the closed-loop torque controlled mode, motion monitoring
functions may be selected as long as it is guaranteed that the encoder signals can be
evaluated.
Special feature in the case of linear motors
The motor encoder (linear scale) of linear motors also acts as load measuring system. Only
one measuring system is required for this reason. The system is connected by means of a
Sensor Module or directly via DRIVE-CLiQ.
NOTICE
When specifying the standstill tolerance window, observe that fail-safe position monitoring
within a single-encoder system only works at a rough resolution with 4 pulses per
revolution.
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Function Manual, (FHS), 11/2009, 6SL3097-4AR00-0BP0
Safety Integrated