Siemens SIMATIC NET Operating Instructions Manual page 16

Description of the device
3.2 Purpose
TAP function
In bypass mode, a SCALANCE XC100-4OBR with TAP function forwards the received data
not only to the neighboring network components. The TAP function has the effect that the
data is also sent to the end device. The end device receives and sends data as if it were
connected to the network. The data that the end device sends in bypass mode is not
forwarded to the network by the bypass relay.
With a bypass relay with TAP function, the end device can establish a link to the neighboring
network components in bypass mode.
Bypass relay with TAP function
If you use a bypass relay with TAP function in MRP or HRP rings, you can activate and
deactivate the connected end device without the redundancy manager initiating
reconfiguration routines in the ring.
Bypass relay without TAP function
If you use a bypass relay without TAP function in MRP and HRP rings, the redundancy
manager reacts when the connected end device is turned on or off again. The redundancy
manager enables the alternative (redundant) ring section and initiates the reconfiguration of
the logical communications connections.
Note
The insertion loss is lower with a bypass relay without TAP function.
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Operating Instructions, 10/2013, C79000-G8976-C297-02
SCALANCE XC100-4OBR