The Series 90 TCP/IP Redundancy Communications enabler can be configured to failover to a secondary cable when communicating to a pair of redundant PLCs. You can implement cabling redundancy with:
One Ethernet LAN and two connections from each PLC to the Ethernet network.
A redundant Ethernet LAN and one connection from each PLC to each cable in the Ethernet LAN.
When you use multiple Ethernet cards in the host computer, the Host IP Address and PLC IP Address in combination with the Subnet Mask of the Ethernet card determines which card/cable combination will be used.