Setting functions
8.9 Safe Torque Off (STO) safety function
Converter with control units CU250D-2
244 Operating Instructions, 04/2014, FW V4.7, A5E34261542B AA
Figure 8-49 Tolerance regarding discrepancy
Filter to suppress short signals
The inverter normally responds immediately to signal changes at its safety-related inputs.
This is not required in the following cases:
● When you interconnect a safety-related input of the inverter with an electromechanical
sensor, contact bounce may result in signal changes occurring, to which the inverter
responds.
● Several control modules test their safety-related outputs using bit pattern tests
(light/darkness tests) to identify faults due to either short-circuiting or cross circuiting.
When you interconnect a safety-related input of the inverter with a safety-related output of
a control module, the inverter responds to these test signals.
A signal change during a bit pattern test usually lasts:
– On test: 1 ms
– Off test: 4 ms
If the safety-related input signals too many signal changes within a certain time, then the
inverter responds with a fault.
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