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3. Fieldbus Integration With Experion System
3.7. CIOM-A FIM Redundancy Functionality
80 Experion PKS Series A Fieldbus Interface Module User's Guide R400
Honeywell July 2010
considered a dual redundant system, which is characterized by the following two main
redundancy states.
Primary - Refers to the chassis executing the assigned control functions.
Secondary - Refers to the chassis in some state of readiness to assume the
responsibilities of the Primary.
REFERENCE - INTERNAL
Please refer to the Controller Redundancy Functionality section in the Control
Builder Components Theory for more information about C200 Controller
redundancy.
Switchover and Secondary readiness
A switchover describes the process where a Secondary chassis assumes the Primary state,
and the Primary chassis assumes the appropriate Secondary state of readiness, depending
upon what triggered the switchover. A switchover can be triggered immediately upon the
detection of a fault in the Primary or upon the receipt of an operator command.
The ability of a Secondary chassis to take over the assigned control functions of the
Primary depends upon which one of the following readiness states reflects its current
state.
If Secondary Chassis State is . . . Then, the Secondary Chassis . . .
Disqualified Cannot assume the Primary state. This is a
state of non-readiness.
Synchronizing Cannot assume the Primary State. In this state,
the Secondary chassis is copying database
information from the Primary.
Synchronized Can assume the Primary state upon
switchover. In this state, the database in the
Secondary is aligned with the database in the
Primary. The Secondary closely tracks
database changes to maintain its
synchronization with the database of the
Primary. Otherwise, the Secondary will revert
to a Disqualified state.