SE-Power FS STO-manual vers. 1.6 en.12.08.2015
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The servo drive SE-Power FS monitors the status of the control ports STO-A and STO-B.
Consequently, the servo drive firmware detects the request for the safety function STO (Safe
Torque Off) and various non-safety functions are then performed:
Detection of deactivated driver supply for the power semiconductor via the safety module
Deactivation of the drive controller and activation of the power semiconductor (PWM)
The holding brake controller is deactivated (if configured)
Finite state machine on the servo drive with activation analysis (discrepancy time)
Detection of application-related error messages
Hardware diagnostics
Status and error display via display, digital outputs, fieldbuses etc.
Note
The brake is activated by the servo drive’s non-safety firmware.
Note
If one of the control ports STO-A or STO-B is deactivated with an active output, the
drive coasts unbraked if no holding brake is connected.
This can cause damage to the machine. It is therefore recommended that a holding
brake is connected to the servo drive.
Please check whether the motors with holding brake you use is designed to
decelerate and bring the motor to a standstill via the holding brake, should
malfunction occur.
The safe state can be requested when the power semiconductor (PWM) is activated. The
two driver supply voltage states are detected and analysed in 10ms cycles. If they are
unequal over a prolonged period, an error message is generated
Section 7.4.2
. The
safety function presupposes that the two signals have the same status. Unequal signals are
tolerated only during a transition period, the so-
called “discrepancy time
Section 4.2.3