Settings For The "Sto" Function - Siemens SINAMICS G120 Operating Instructions Manual

Functions
5.12 Safety functions
5.12.6

Settings for the "STO" function

You can make two settings for the STO safety function.
Testing the shutdown paths
Shutdown paths are electronic circuits of the inverter used to disconnect a motor in a safety-
relevant fashion. The shutdown paths must be checked regularly to ensure that the fail-safe
inverter complies with certification requirements.
The shutdown paths are always checked after the inverter has been switched on. Further,
the inverter always checks, in its factory setting, the shutdown paths if the STO function is
de-selected.
The shutdown path test takes approximately three seconds. The motor cannot be switched
on during the test. The inverter signals this status as 'switch on inhibit' in the status word
(r0052, bit 6). A higher-level control must evaluate this bit to ensure that the inverter accepts
the ON command.
Deactivating the shutdown path test after an ON command
For applications where the STO safety function is very frequently required, the delay caused
by testing the shutdown paths can be disturbing. If you wish to avoid the waiting time after
each STO request, deactivate the regular shutdown path test when exiting the STO function
(P9601, bit 1 and P9801, bit 1).
1. Connect your PC to the inverter e.g. using the PC connection kit.
2. Launch the STARTER parameterization tool and go online.
3. In STARTER, call up the screens displaying the fail-safe functions.
4. Select the "Safe Torque Off (STO)" screen from the safety function screens
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CU240S and CU240E Control Units, FW 3.2
Operating Instructions, 03/2009, A5E02440075B AA