7.13
Date Code 20170814
Instruction Manual
SEL-700G Relay
Communications
Communications Protocols
SNTP as Primary or Backup Time Source
If an IRIG-B time source is connected and either Relay Word bit TSOK or
Relay Word bit IRIGOK asserts, then the relay synchronizes the internal time-
of-day clock to the incoming IRIB-G time code signal, even if SNTP is
configured in the relay and an NTP server is available. If the IRIG-B source is
disconnected (if both TSOK and IRIGOK deassert) then the relay
synchronizes the internal time-of-day clock to the NTP server, if available. In
this way, an NTP server acts either as the primary time source or as a backup
time source to the more accurate IRIG-B time source.
Creating an NTP Server
Three SEL application notes, available from the SEL website, describe how to
create an NTP server.
➤
AN2009-10: Using an SEL-2401, SEL-2404, or SEL-2407 to
Serve NTP Via the SEL-3530 RTAC
➤
AN2009-32: Using SEL Satellite-Synchronized Clocks With the
SEL-3332 or SEL-3351 to Output NTP
➤
Using an SEL-2401, SEL-2404, or SEL-2407 to Create a
Stratum 1 Linux NTP Server
Configuring SNTP Client in the Relay
To enable SNTP in the relay, make Port 1 setting ESNTP = UNICAST,
MANYCAST, or BROADCAST. Table 7.4 shows each setting associated with
SNTP.
SNTP Operation Modes
The following sections explain the setting associated with each SNTP
operation mode (UNICAST, MANYCAST, and BROADCAST).
ESNTP = UNICAST
In unicast mode of operation, the SNTP client in the relay requests time
updates from the primary (IP address setting SNTPPSIP) or backup (IP
address setting SNTPBSIP) NTP server at a rate defined by setting
Table 7.4
Settings Associated With SNTP
Setting
Range
Description
ESNTP
UNICAST,
MANYCAST,
BROADCAST
Selects the mode of operation of SNTP. See
descriptions in SNTP Operation Modes.
SNTPPSIP
Valid IP Address
Selects primary NTP server when ENSTP = UNICAST,
or broadcast address when ESNTP = MANYCAST or
BROADCAST.
SNTPPSIB
Valid IP Address
Selects backup NTP server when ESNTP = UNICAST.
SNTPPORT
1–65534
Ethernet port used by SNTP. Leave at default value
unless otherwise necessary.
SNTPRATE
15–3600 seconds
Determines the rate at which the relay asks for updated
time from the NTP server when ESNTP = UNICAST
or MANYCAST. Determines the time the relay will
wait for an NTP broadcast when
ENSTP = BROADCAST.
SNTPTO
5–20 seconds
Determines the time the relay will wait for the NTP
master to respond when ENSTP = UNICAST or
MANYCAST.
Содержание SEL-700G Series
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