7.13
C300 operating behaviors
This section describes some of the C300 Controller's features and operating behaviors
related to event and alarm reporting.
Time management in the C300 Controller
The C300 Controller requires a reliable and high quality time source to correlate events
from other devices in the system. Simple Network Time Protocol (SNTP), from a
dedicated Network Time Protocol (NTP) Server is the preferred time source for the
controller, although the controller can operate using other time sources, such as SNTP or
CDA from Experion LX Server.
The C300 synchronizes its local clock through NTP at startup and every minute. In the
absence of SNTP, the local clock is synchronized with CDA on first connection and
every minute.
Refer to the Setting up time synchronization in the Supplementary Installation Tasks
Guide for information on setting up a system time server.
Adjustments to time occur in the controller to maintain synchronization with the time
source. If the difference between the system time source and the controller's wall clock
time (WCT) is less than 5 minutes, then time is adjusted in increments. If the controller's
WCT differs by more than 5 minutes with the time source, controller time is set to match
the time source with an immediate correction. An information notification is generated
by the controller and sent to the events server.
Note that the controller’s WCT is lost during loss of power and cannot be restored in
RAM retention start scenario. Therefore, the controller will not have any information
regarding the WCT during the absence of Server. This affects the system planning and
controller usefulness. The time in the controller cannot be used reliably for control
applications.
Time synchronization between a primary and secondary C300 Controller is maintained
by the redundancy sub-system. The primary controller passes its WCT to the secondary
controller. Time adjustments are made to achieve time synchronization between the
redundant controller pair.
The C300 also maintains a Sequence Of Events (SOE) clock to synchronize to the system
time source (whenever one is available). Time adjustment occurs in a similar manner,
except that the SOE clock will be set to match the time source whenever a difference
between the source and the SOE clock exceeds 5 seconds.
Note that in the absence of an NTP time source, SOE event correlation is degraded across
a controller switchover. Events occurring before switchover are consistent, and events
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