Siemens SINAMICS G120 Function Manual page 80

Interfaces
3.2 Activation via F-DI
Bit pattern test of fail-safe outputs and contact bounces of sensors
The inverter normally responds immediately to signal changes in its fail-safe inputs. This is
not required in the following cases:
1. When you interconnect a fail-safe input of the inverter with an electromechanical sensor,
2. Several control modules test their fail-safe outputs using bit pattern tests (on/off tests), in
When the signal for STO control in "Basic Safety" is not "stable", the inverter responds to this
by means of a fault.
(Definition of a stable signal: Following a change to the F-DI input signals, the inverter
triggers an internal monitoring time. Up until the end of the time interval 5 x p9650, both input
signals must have a constant signal level. A constant signal level is a high or a low state, for
a period of at least p9650).
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contact bounce may result in signal changes occurring, to which the inverter responds.
order to identify faults due to either short or cross circuiting. When you interconnect a 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:
– Bright test: 1 ms
– Dark test: 4 ms
Figure 3-2 Inverter response to a bit pattern test
Safety Integrated Function Manual, SINAMICS G120 and G120C
Function Manual, 01/2011, FW 4.4, A5E03052391B AB