8. C300 Redundancy operation 
8.8. C300 Redundancy-related notifications 
Series 8 C300 Controller User's Guide 
Honeywell 
formally tested with redundant controllers prior to
 
distribution, marginal hardware is the most likely culprit.
 
Moreover, the full redundancy communication path has to be
 
considered: 
 
In C300 Controllers: 
Primary C300 -> Primary IOTA -> Private Path Cable ->
 
Secondary IOTA -> Secondary C300. 
 
Sync Checksum Fail is detected by the secondary controller
 
which aborts synchronization and generates this alarm
 
notification.  Detection of Sync Checksum Fail is severe in
 
that the redundant controller pair were allegedly
 
synchronized when redundancy tracked memory was found
 
to be different.  In other words, switchover in the presence of
 
redundancy tracked memory differences may lead to bump
 
in control or loss of control (where the scope of the failure
 
varies on where and how the memory differed).  Therefore,
 
by design, a Sync Checksum Fail occurrence disables auto
 
synchronization. 
 
Hardware replacement is recommended upon Sync
 
Checksum Fail detection. 
 
This notification returns to normal upon issuing the Enable
 
Sync or Alternate Sync commands. 
Sync Hardware Failure is detected locally by the primary or
 
secondary controller which aborts synchronization and
 
generates this alarm notification.  Detection of Sync
 
Hardware Failure is severe in that the redundant controller
 
pair could possibly repetitively synchronize and abort
 
synchronization continuously (unless 3 consecutive initial-
 
sync failures occur).  Therefore, by design, a Sync Hardware
 
Failure occurrence disables auto synchronization. 
 
Hardware replacement is recommended upon Sync
 
Hardware Failure detection. 
 
This notification returns to normal upon issuing the Enable
 
Sync or Alternate Sync commands. 
Read description of Standby state. 
 
Upon entering the Standby state, this diagnostic alarm warns 
users of the potential switchover to the CEE Idle
  
state.  This notification returns to normal upon exiting the
 
Standby state either due to controller redundancy switchover
 
or the Disable Sync command. 
Unexpected Partner
 
on Redundancy 
Only the controller explicitly configured non-redundant
 
generates this alarm notification when a partner is present 
PARTNERVISBL or
 
INCOMPATIBLE