Siemens SINAMICS G120 CU240E-2 - Page 217

Functions
7.10 Safe Torque Off (STO) safety function
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
217
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Figure 7-24 Filter for suppressing discrepancy monitoring
The filter does not increase the inverter response time. The inverter activates its safety
functions as soon as one of the two F-DI signals changes its state from high to low.
Bit pattern test of fail-safe outputs and contact bounces of sensors
The inverter normally responds immediately to signal changes at its fail-safe input. This is
not required in the following cases:
1. When you interconnect the fail-safe input of the inverter with an electromechanical
sensor, contact bounce may result in signal changes occurring, to which the inverter
responds.
2. Several control modules test their fail-safe outputs using bit pattern tests (on/off tests), in
order to identify faults due to either short or cross circuiting. When you interconnect the
fail-safe input of the inverter with a fail-safe output of a control module, the inverter
responds to these test signals.
A signal change during a bit pattern test usually lasts 1 ms.
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Figure 7-25 Inverter response to a bit pattern test