SE-Power FS STO-manual vers. 1.6 en.12.08.2015
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4.2.3.1
Discrepancy time
The transition between the safe and the unsafe state is initiated via level changes at the
control ports STO-A and STO-B of the safety module FSM 2.0
– STO. According to the
safety function specification, the two levels must be identical otherwise an error message will
be generated. The finite state machine in the servo drive internally monitors the driver supply
voltage after the control ports have been activated. Due to component tolerances or
bouncing safety controller ports, for example, these level changes do not normally occur
precisely at the same time. The firmware tolerates this for as long as the second input occurs
within a defined time, the so-called discrepancy time. If this time is exceeded, the servo drive
generates an error message.
The default discrepancy time is 100ms.
Recommendation: Always switch STO-A and STO-B simultaneously.
4.2.3.2
Test pulse
Temporary test pulses from safety controllers are tolerated and thus do not trigger the STO
function.
The tolerance to test pulses from sensors with OSSD signals is rated for the operating range
specified in accordance with
Appendix
. The permissible test pulse length is
dependent upon the control voltage level at inputs STO-A and STO-B.
Example:
Input voltage for STO-A and STO-B = 24 V
OSSD signals with a test pulse length of 3.5ms are tolerated.
4.2.4
Feedback contact C1, C2 [X40]
If the STO function is inactive, the feedback contact opens. This is the case, for example,
when only one of the two control voltages STO-A or STO-B is present, if the 24 V logic power
supply is switched off or if the supply voltage fails.
When the STO function is active, the relay contact is closed.
The feedback contact has a single channel and may be used for diagnostic
purposes, but not in the safety circuit.
describes the electrical data,
the time response
of the feedback contact. When the 24 V supply to the basic device is turned on and
off, the switching status of the relay may
– due to the internal supply voltages
powering up at a different speed
– deviate briefly (approx. 100ms) from the state of
the control ports STO-A and STO-B.
