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If Network Activity Is . . .
Link Active Scheduler (LAS)
Alert Queued, User Triggered,
Unidirectional Multicast (QUU)
VCR
Subscriber Buffered, Network
scheduled, Unidirectional
broadcast (BNU) VCR
Publisher Buffered, Network
scheduled, Unidirectional
broadcast (BNU) VCR
Client Queued, User triggered,
Bi-directional peer-to-peer
(QUB) VCR
R400
Experion PKS Series A Fieldbus Interface Module User's Guide
July 2010
3. Fieldbus Integration With Experion System
3.7. CIOM-A FIM Redundancy Functionality
Then, Behavior During Switchover Is . . .
The Primary LAS runs the link schedule by telling
devices to publish their data at specific times. The
Secondary FIM link is a backup LAS with a valid
copy of the link schedule. During switchover, it
skips the remainder of the current macrocycle and
starts running its schedule from time zero of next
macrocycle. Unlike backup LAS devices, the
Secondary FIM has full LAS schedule with FIM
publications.
Both Primary and Secondary FIM links subscribe to
alerts from devices and receive them in parallel.
Only the Primary FIM link reports received alerts
through the CDA server to the operator interface.
After switchover, the new Primary FIM starts and
the old Primary FIM stops submitting alerts to the
CDA server. The new primary FIM regenerates its
alarms. This action covers whatever alarms might
have been acknowledged just prior to switchover
but did not get submitted to Server as a result of
event throttling.
Both Primary and Secondary links subscribe to the
same data published by a given device. Secondary
has its VCR open and receives publications in
parallel with the Primary. No specific action needs
to be taken during switchover or swap.
Only acting Primary FIM link can publish data to
fieldbus devices. Both Primary and Secondary can
be configured with the same publication endpoint
connection, but only the Primary link has this
connection open and active at a time. During
switchover, the old Primary closes its connection
and consequently stops publishing. The old
Secondary, that is becoming new Primary, opens
its connection and consequently starts publishing.
All client-server connections are broken and re-
established. This way new Primary builds fresh
connection context.
QUB connections are point-to-point and therefore
can only be opened from the primary.
FIM maintains one Management Information Base
Honeywell
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