Rockwell Automation 1734-AENTR EtherNet/IP Network Configuration User Manual - Manual (Page 30)

30 Rockwell Automation Publication ENET-UM001L-EN-P - March 2014
Chapter 3 Configure an EtherNet/IP Communication Module to Operate on the Network
Duplicate IP Address Resolution
When two EtherNet/IP communication modules on a network have conflicting
IP addresses, the resolution depends on the conditions in which the duplication is
detected. This table describes how duplicate IP addresses are resolved.
Devices experiencing duplicate IP address conditions behave differently
depending on whether connections have been established to either of the
modules and whether both modules support duplicate IP address detection.
IP Address Swapping Some EtherNet/IP communication modules support IP address swapping. This
functionality is used in ControlLogix enhanced redundancy systems. During a
system switchover, partnered EtherNet/IP communication modules swap IP
addresses.
For more information about IP address swapping, see the ControlLogix
Enhanced Redundancy System User Manual, publication
1756-UM535 .
Duplicate IP Address Detection Conditions Resolution Process
• Both modules support duplicate IP address detection
• Second module is added to the network after the first
module is operating on the network
1. The module that began operation first uses the IP address and continues to operate without interruption.
2. The module that begins operation second detects the duplication and enters Conflict mode.
To assign a new IP address to the module and leave Conflict mode, see Set the Network IP Address on a Module
on page 18 .
• Both modules support duplicate IP address detection
• Both modules were powered up at approximately the same
time
Both EtherNet/IP devices enter Conflict mode.
To resolve this conflict, follow these steps:
a. Assign a new IP address to one of the modules by using the methods described in Set the Network IP
Address on a Module on page 18 .
b. Cycle power to the other module.
One module supports duplicate IP address detection and a
second module does not 1. Regardless of which module obtained the IP address first, the second module, that is, the module that does not
support IP address detection, uses the IP address and continues to operate without interruption.
2. The module that supports duplicate IP address detection detects the duplication and enters Conflict mode.
To assign a new IP address to the module and leave Conflict mode, see Set the Network IP Address on a Module
on page 18 .