Rockwell Automation Allen-Bradley 1794-IB16D - Duplicate Detection Scenarios

Rockwell Automation Publication 1794-UM061B-EN-P - March 2020 103
Configure your Digital Module on an EtherNet/IP Network Chapter 7
•OK indicator blinks red.
• network (NET) indicator is solid red.
• front display indicates the conflict (1756-ENBT only).
The display scrolls: ”OK <IP_address_of_this_module> Duplicate IP
<Mac_address_of_duplicate_node_detected>”
For example: OK 10.88.60.196 Duplicate IP - 00:00:BC:02:34:B4
To correct this conflict, use the instructions in this chapter to change the IP
address of the module. Then cycle power to the module or reset the module (such
as disconnecting the EtherNet/IP cable and reconnecting the cable).
There is also the possibility that two modules can detect a conflict
simultaneously. If this occurs, remove the module that has the incorrect IP
address or correct its conflict. To get the second module out of conflict mode,
cycle power to the module or disconnect its EtherNet/IP cable and reconnect the
cable.
Duplicate detection scenarios
• The behavior of devices that are in conflict over an IP address varies
depending on whether connections have been established to either of the
modules and whether both modules support duplicate IP address
detection:
• If both modules support duplicate IP address detection, the module that
powers up first and uses the IP address, keeps the IP address. The other
module will detect a conflict, give up the IP address, and enter conflict
mode.
• If both modules support duplicate IP address detection and both modules
power up at roughly the same time, both modules give up the IP address
and enter conflict mode.
• If one module supports duplicate IP address detection and a second
module does not, the second module generally keeps it IP address,
regardless of which module obtains the IP address first. The module that
supports duplicate IP address detection will detect the conflict and give up
the IP address.