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3. Fieldbus Integration With Experion System
3.7. CIOM-A FIM Redundancy Functionality
For this Switchover Consideration . . .
Online Address Swap
Switchover versus fieldbus network activities
The following table summarizes how given fieldbus network activities behave during a
switchover.
ATTENTION
Depending upon the link communication load, number of devices, and type of
parameter, fresh viewed data from field devices may be delayed for up to 20
seconds during a CIOM-A FIM chassis switchover. This does not apply to
control data.
If Network Activity Is . . .
Link Maintenance
System Management
Operations
84
Experion PKS Series A Fieldbus Interface Module User's Guide
FIM Redundancy Operation . . .
Swaps network addresses between
Primary and Secondary FIM links. The
link addresses are 16 for the Primary FIM
and 17 for the Secondary FIM. During
switchover or swap, the Secondary FIM
becomes the Primary FIM and assumes
address 16, while the Primary FIM
becomes the Secondary FIM and
assumes address 17 or is Disqualified.
The Primary FIM continues Link Master
operations.
Then, Behavior During Switchover Is . . .
Since Secondary FIM link is a backup Link Active
Scheduler (LAS), it resumes network management
activities as soon as it detects that the old Primary
FIM is no longer there.
Both Primary and Secondary FIM links have the
same knowledge of current time. When new
Primary takes over as acting Link Master, it also
becomes acting time publisher.
Any System Management operation that is in
progress is interrupted. For example, the new
Primary does not know anything about pending
change tag or address operation. As a result,
device whose address or tag is being changed will
timeout and abort the operation.
Honeywell
R400
July 2010
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