Schweitzer Engineering Laboratories SEL-421-4 - Page 1284

15.14
SEL-400 Series Relays Instruction Manual Date Code 20171006
Communications Interfaces
Ethernet Communications
an NTP server is available. If the IRIG-B source is disconnected (TIRIG deas-
sert) then the relay synchronizes the internal time-of-day clock to the NTP server
if available. In this way an NTP server acts as either the primary time source, or
as a backup time source to the more accurate IRIG-B time source. The above is
also true if the relay is connected to an accurate PTP time source, but TPTP (not
TIRIG) will deassert when the PTP time source is disconnected.
Three SEL application notes available from the SEL web site 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
➤ AN2009-38: Using SEL Satellite-Synchronized Clocks With the
SEL-3332 or SEL-3354 to Output NTP
➤ AN2010-03: 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 5 setting ESNTP = UNICAST, MANY-
CAST, or BROADCAST. Table 1 5.9 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).
Table 15.9 Settings Associated With SNTP
Setting Prompt Range Default Description
ESNTP SNTP Enable (OFF, UNICAST,
MANYCAST, BROADCAST)
UNICAST,
MANYCAST,
BROADCAST
OFF Selects the mode of operation of SNTP. See
descriptions in SNTP Operation Modes on
page 15.14.
SNTPRAT
a
SNTP Request Update Rate
(15–3600 s)
15–3600 s 60 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 SNTP Timeout (5–20 s) 5–20 s 5 Determines the time the relay will wait for the NTP
master to respond when ENSTP = UNICAST or
MANYCAST.
SNTPPIP SNTP Primary Server IP
Address (w.x.y.z)
b
Valid IP Address 192.168.1.110 Selects primary NTP server when
ENSTP = UNICAST, or broadcast address when
ESNTP = MANYCAST or BROADCAST.
SNTPBIP SNTP Backup Server IP
Address (w.x.y.z)
c
Valid IP Address 192.168.1.111 Selects backup NTP server when
ESNTP = UNICAST.
SNTPPOR
d
SNTP IP Local Port Number
(1–65534)
1–65534 123 Ethernet port used by SNTP. Leave at default value
unless otherwise required.
a
This setting is hidden if ESNTP = OFF and hidden and forced to 5 if ESNTP = BROADCAST.
b
Where w: 0–126, 128–239, x: 0–255, y: 0–255, z: 0–255.
c
Where w: 0–126, 128–223, x: 0–255, y: 0–255, z: 0–255.
d
This setting is hidden if ESNTP  UNICAST.