Rockwell Automation 1756-OF8H ControlLogix HART Analog I/O Modules - Manual (Page 50)

50 Rockwell Automation Publication 1756-UM533C-EN-P - February 2011
Chapter 3 ControlLogix Module Operation
When multiple controllers are configured to own the same input module, the
following events occur:
• When the controllers begin downloading configuration data, both try to
establish a connection with the input module.
• Whichever controller’s data arrives first establishes a connection.
• When the second controller’s data arrives, the module compares it to its
current configuration data (the data received and accepted from the first
controller).
– If the configuration data sent by the second controller matches the
configuration data sent by the first controller the connection is also
accepted.
– If any parameter of the second configuration data is different from the
first, the module rejects the connection; RSLogix 5000 software alerts
you to the rejected connection through an error message.
The advantage of multiple owners over a Listen-only connection is that now
either of the controllers can lose the connection to the module and the module
continues to operate and multicast data to the system because of the connection
maintained by the other owner-controller.