Rockwell Automation 1756-RMxx ControlLogix Enhanced Redundancy System User Manual - Manual (Page 220)

220 Rockwell Automation Publication 1756-UM535D-EN-P - November 2012
Chapter 9 Troubleshoot a Redundant System
Partner Network Connection
Lost
If a partner network connection between a redundant chassis pair is lost, a state
change or switchover may occur. These state changes may result:
• Primary with qualified secondary changes to primary with disqualified
secondary
• Qualified secondary with primary to disqualified secondary with primary
To use the Event Log to determine if a lost partner network connection caused a
state change, complete these steps.
1. Open RSLinx Classic software and access the RMCT of the primary
redundancy module.
This is the chassis that was previously the secondary but is now the
primary.
2. Locate the last event that indicates successful qualification and status.
3. Open the Event Log for the secondary chassis because the cause of the
switchover is not apparent.
IMPORTANT This example shows a connection lost over a ControlNet network. You same
steps apply if the connection is lost over an EtherNet/IP network.
Primary Chassis
Secondary Chassis
Primary Chassis
Event Log
Event indicates chassis
state is as a qualified
secondary.
A switchover is
initiated.
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