Siemens SIMATIC NET Operating Instructions Manual page 15

Bypass mode
If the voltage of the end device drops, for example due to a fault or during maintenance, the
voltage of the SCALANCE XC100-4OBR also drops. The monitoring voltage is no longer in
the set range.
The bypass relay then interconnects its two network interfaces within 10 ms. As result, the
connection to the end device that has been turned off is inactive and the bypass relay forms
the connection to the neighboring network components or bypass relays
When you turn on the voltage of the end device and therefore of the SCALANCE XC100-
4OBR again, the two network interfaces remain connected until the end device is
operational. It is only after this startup time that the bypass relay connects the network
interfaces to the end device interfaces again.
SCALANCE XC100-4OBR
Operating Instructions, 10/2013, C79000-G8976-C297-02
Description of the device
3.2 Purpose
②
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