Rockwell Automation 284E ArmorStart with EtherNet/IP - User Manual - Manual (Page 63)

Rockwell Automation Publication 280E-UM001B-EN-P - July 2012 63
Introduction to EtherNet/IP and Device Level Ring Technology Chapter 3
Figure 45 - Physical Layer Failure is Detected
When the physical layer fault is corrected the supervisor will “hear” the beacon
frame again on both ports. Once this is detected the ring supervisor re-establishes
and configures the ring topology. All the neighboring nodes detect this and
reconfigure themselves back to ring. A DLR network is a single-fault tolerant
network intended for the interconnection of automation devices.
At least one ring supervisor must be configured before a ring is formed.
The node should be connected to the ring through a switch that supports DLR.
The advantages of the DLR network include:
• simple installation
• resilience to a single point of failure on the network
• fast recovery time when a single fault occurs on the network
The primary disadvantage of the DLR topology is the additional effort required
to set up and use the network as compared to a linear or star network.
IMPORTANT Any nodes that do not support DLR should not be directly connected to the ring.
IMPORTANT Products with EtherNet/IP embedded switch technology have two ports to connect to
a linear or DLR network in a single subnet.
You cannot use these ports as two Network Interface Cards (NICs) connected to two
different subnets.
IMPORTANT ArmorStart EtherNet/IP is cannot be configured as a ring supervisor.