Allen-Bradley FLEX I/O Dual-port EtherNet/IP communication adapters simplify network design and increase network resiliency.
Rockwell Automation introduced its Allen-Bradley FLEX I/O dual-port EtherNet/IP adapters that support a device-level ring (DLR) topology (connected at the end device versus the switch). The ring adds a measure of redundancy in that a single network failure, such as a cable break, will not lead to the failure of the other devices in the ring. It can also recover in less than 3 milliseconds for a 50-node system. The adapters also support the daisy-chain topology for applications that involve devices located long distances from CPU subsystems.
The adapters (1794-AENTR and 1794-AENTRXT for extreme environments) are compatible with these Rockwell Software products: RSLogix 5000 programming software version 16 and higher and RSLinx version 2.58 and higher. The adapters also can connect up to eight FLEX I/O modules.
http://ab.rockwellautomation.com/IO/1794-FLEX-IO-Communication-Interfaces