User manual

Publication ENET-UM001I-EN-P - January 2010 53
Configure an EtherNet/IP Module to Operate on the Network Chapter 4
Detection of Duplicate IP Addresses
Devices in conflict over an IP address 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
This EtherNet/IP modules supports IP address swapping in ControlLogix
redundancy systems:
• 1756-ENBT, firmware revision 3.1 and later
• 1756-EN2T, firmware revision 2.003 and later
• 1756-EN2TR, firmware revision 2.x and later
• 1756-EN2TXT, firmware revision 2.1 and later
During a switchover in ControlLogix redundancy systems
,
these module swaps
its IP address with its partner modules in the other redundant chassis.
For more information about IP address swapping, see
the ControlLogix
Redundancy User Manual
, publication 1756-UM523 . When using publication
1756-UM23, be aware that neither the 1756-EN2TR module
nor the
1756-EN2TXT module supports redundancy.
Device Conflict Over Duplicate IP Addresses
If Then
Both modules support duplicate IP address
det
ection
The first started module uses and retains its IP address.
The other module will detect a conflict, give up the IP address and enter conflict mode.
Both modules support duplicate IP address
detection and are started at roughly the same
time
They surrender the IP address
and enter conflict mode
One module supports duplicate IP address
d
etection and a s
econd module does not
The second module generally keeps its IP address, regardless of which module first
obtains the IP address.
The module that supports duplicate IP address detection w
ill detect the conflict and
give up the IP address.