Advanced commissioning
7.7 Safe Torque Off (STO) safety function
SIMATIC ET 200pro FC-2 converter
Operating Instructions, 04/2018, FW V4.7 SP10, A5E34257324B AF
123
7.7.3.6
Setting the STO input signal
Procedure
1.
Select the advanced settings for STO.
2.
Set the debounce time of the STO input signal.
We recommend that you leave the debounce time set in the factory (1 ms).
3.
Close the screen form.
You have set the input filter of the STO input signal.
❒
Filter to suppress short signals
The inverter normally responds immediately to signal changes of the F0 bus. The F switch
tests the F0 bus using a "bit pattern test" (off test) in order to identify faults caused by short-
circuits or cross-circuits.
A signal change during a bit pattern test usually lasts:
●
Off test: 1 ms
If the inverter identifies too many signal changes within a certain time, then it responds with a
fault.
Figure 7-11 Inverter response to the off test of the F0 bus
In order to avoid an undesirable inverter response, a signal filter in the inverter suppresses
the off test of the F0 bus.
