Allen-Bradley 1756-CNB/E, User Manual

Page: 155 / 186

Publication 1756-UM523F-EN-P - December 2006
Set Up EtherNet/IP Communication Across Subnets 155
To keep a Message (MSG) instruction going to the new primary
chassis after a switchover:
•
create a periodic trigger for the messages.
•
obtain the redundancy state of chassis A.
•
obtain the redundancy state of chassis B.
•
determine which chassis is primary.
•
send the message to the appropriate controller.
Create a Periodic Trigger for the Messages
E
N
B L
x
E
N
B L
5
5
Chassis B
MSG
Type - CIP Generic
MSG
Type - CIP Generic
E
N
B
T L
5
5
M
Chassis A
Free-running timer that triggers the execution of MSG instructions. The timer runs for 2 seconds (2000 ms) and then resets
and starts timing again. Every 2 seconds, Timer_RedundancyMSGs.DN = 1 for a single scan. The MSG instructions use this
bit as one of their conditions for execution.
Tag Name Description Alias For Data Type
Timer_RedundancyMSGs Periodic trigger for the
execution of MSG
instructions. Triggers MSGs
every 2 s. TIMER