Siemens SINAMICS G120 Function Manual page 142

Alarms, faults and system messages
6.2 Disturbance characteristics of the safety functions
Response in the event of a discrepancy
A discrepant signal at a fail-safe input, e.g. caused by a cable break, results in safety
function SS1 being selected. After the tolerance time has expired, the inverter signals the
discrepancy (alarm C01770 or C30770) but does not interrupt the braking operation for the
motor.
Figure 6-6
To switch the motor on again, proceed as follows:
1. Rectify the discrepancy.
2. Acknowledge the active messages (see Section Acknowledging faults using a fail-safe
142
Response of safety function SS1 in the event of a discrepancy
signal (Page 136)).
Note: In this case, it is not possible to acknowledge by selecting and deselecting STO.
Safety Integrated Function Manual, SINAMICS G120
Function Manual, 07/2010, FW 4.3.2, A5E03052391B AA