8.15.2.4
Signal filter for STO selection
Overview
Two filters are available for a failsafe digital input:
• When the discrepancy time is active, the converter tolerates input signals that briefly differ.
• When the debounce time is active, the converter suppresses brief signal changes.
Function description
Discrepancy time
The converter checks that the two input signals of the failsafe digital input always have the same
signal state (high or low).
With electromechanical sensors (e.g. emergency stop buttons or door switches), the two sensor
contacts switch, but never at exactly the same time, and are therefore temporarily inconsistent
(discrepancy).
Only a permanent discrepancy signifies a fault in the failsafe digital input circuit, e.g. wire
breakage.
You must set the discrepancy time to ignore signals that are briefly inconsistent.
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Figure 8-33
Discrepancy time
The discrepancy time does not extend the converter response time. The converter activates the
safety functions as soon as one of the two F-DI signals changes its state from high to low.
Advanced commissioning
8.15 Safe Torque Off (STO) safety function
Distributed converter for SIMOGEAR geared motors
Operating Instructions, 10/2020, FW V4.7 SP13, A5E31298649B AL
249