Siemens SINAMICS G115D Operating Instructions Manual page 196

Advanced commissioning
6.13 Safe Torque Off (STO) safety function
Filter for suppressing short signals
In the following cases, an immediate converter response to signal changes of the fail-safe
digital inputs is not desirable:
• If a fail-safe digital input of the converter is interconnected with an electromechanical
sensor, signal changes can occur due to contact bounce.
• In order to identify faults due to short-circuit or cross faults, several control modules test
their fail-safe digital outputs with "bit pattern tests" (bright/dark test). If a fail-safe digital
input of the converter is interconnected with a fail-safe digital output of an open-loop
control module, then the converter responds with a bit pattern test.
The typical duration of the signal change within a bit pattern test:
– On test: 1 ms
– Off test: 4 ms
If the fail-safe digital input responds to many signal changes within a certain time, then the
converter responds with a fault.
A filter in the converter suppresses brief signals as a result of the bit pattern test or contact
bounce.
The filter extends the response time of the safety function by the debounce time.
Setting the filter for fail-safe digital inputs
Precondition
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Operating Instructions, 09/2020, FW V4.7 SP13, A5E48681219B
SINAMICS G115D distributed drive