Rockwell Automation Publication 1756-UM004C-EN-P - June 2021 41
Chapter 3 Connect Redundant EtherNet/IP Adapters
Redundant Architecture
Network Considerations
In a star topology with a single switch, if a link is broken between the switch
and the primary redundant adapter, a switchover will occur. With multiple
switches, for example as shown in Figure 11
, if a link is broken between two
switches, a switchover will not occur because the link to the redundant adapter
is still in place.
Figure 11 - Invalid Topology: Network Break does not Cause Switchover
The Primary Adapter does not detect data connection loss on non-directly
connected links. For example in Figure 12
, the secondary adapter disqualifies
because it cannot detect the primary adapter.
This action occurs even though the secondary adapter still has a healthy path to
the primary controller.
Similarly, the secondary controller in the redundant controller pair
disqualifies because it cannot detect the primary.
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Redundancy Module
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