User Manual
Chapter 4
GFK-2849A
Oct 2019
System Operation
98
4.7.2
SNTP Operation
An SNTP network server sends out a periodic timing message to all SNTP-capable Ethernet
interfaces on the network. The presence of an SNTP server on the network this allows the
ECM850 synchronize its internal clock with this SNTP timing message. The default mode of
SNTP operation is Broadcast and Multicast.
Note
:
The use of SNTP Servers dated before January 1, 1989 is not supported.
4.7.3
Multiple SNTP Servers in a Network
To guard against loss of SNTP timing messages, multiple SNTP servers can be tracked on a
network. The ECM850 maintains timing information from up to four SNTP servers. Each
server assigns a stratum number that determines its priority. ECM850 uses the message
from the server with the lowest stratum number until communication with that server is
lost. (A server is considered lost if more than 150 seconds elapse between its timing
messages.) If communication with a server is lost, the ECM850 synchronizes with the server
with the next lowest stratum number as soon as two of its timing messages are received
within a 150-second period.
4.7.4
Loss or absence of SNTP Timing Signals
If the ECM80 is configured for SNTP, but fails to receive timing messages from an SNTP
network time server within a 150 second period, the ECM850 does the following:
1.
A fault is logged in the RX3i Controller Fault Table.
2.
A fault is logged in the Local Log of the ECM850.
3.
The ECM850 continues to use the time synchronized at power-up/restart with the
controller's local clock, or
4.
it continues to use the most recently synchronized time from SNTP Server before
that signal was lost.
For more information on SNTP events, refer to SNTP Events in section 5.6.2 .
For more information on the SNTP CLI command, refer to section A-3 ECM850 Commands,
Show Sntpstat.
4.8
Hot Standby (HSB) Operation for ECM850
The ECM850 can be used with PACSystems RX3i Hot standby system with RX3i CRU320.
This section describes how the ECM850 can be used in such system. Refer to the
PACSystems Hot Standby CPU Redundancy User's Manual, GFK-2308 for details of Hot
standby operation.
4.8.1
Basic HSB System Overview
The basic system architecture for an HSB system with an ECM850 and IEC 61850 network is
shown in the diagram.
