Siemens SINAMICS G120D Operating Instructions Manual page 184

Setting functions
8.8 Safe Torque Off (STO) safety function
The tolerance time does not extend the inverter response time. The inverter selects its safety
function as soon as one of the two F-DI signals changes its state from high to low.
Figure 8-30
Filter to suppress short signals
The inverter normally responds immediately to signal changes at its safety-related inputs.
This is not required in the following cases:
● When you interconnect a safety-related input of the inverter with an electromechanical
sensor, contact bounce may result in signal changes occurring, to which the inverter
responds.
● Several control modules test their safety-related outputs using bit pattern tests
(light/darkness tests) to identify faults due to either short-circuiting or cross circuiting.
When you interconnect a safety-related input of the inverter with a safety-related output of
a control module, the inverter responds to these test signals.
A signal change during a bit pattern test usually lasts:
– On test: 1 ms
– Off test: 4 ms
If the safety-related input signals too many signal changes within a certain time, then the
inverter responds with a fault.
184
Tolerance regarding discrepancy
Converter with control units CU240D-2
Operating Instructions, 04/2014, FW V4.7, A5E34262100B AA