Sel SEL-787 - Table 7.4 Settings Associated with SNTP

7.13
Date Code 20150130 Instruction Manual SEL-787 Relay
Communications
Communications Protocols
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
SNTPRATE. If the NTP server does not respond with the period defined by
setting SNTPTO, then the relay tries the other SNTP server. When the relay
successfully synchronizes to the primary NTP time server, Relay Word bit
TSNTPP asserts. When the relay successfully synchronizes to the backup
NTP time server, Relay Word bit TSNTPB asserts.
ESNTP = MANYCAST
In the MANYCAST mode of operation, the relay initially sends an NTP
request to the broadcast address contained in setting SNTPPSIP. The relay
continues to broadcast requests at a rate defined by setting SNTPRATE. When
a server replies, the relay considers that server to be the primary NTP server,
and switches to UNICAST mode, asserts Relay Word bit TSNTPP, and
thereafter requests updates from the primary server. If the NTP server stops
responding for time SNTPTO, the relay deasserts TSNTPP and begins to
broadcast requests again until the original or another server responds.
ESNTP = BROADCAST
If setting SNTPPSIP = 0.0.0.0 while setting ESNTP = BROADCAST,
the relay will listen for and synchronize to any broadcasting NTP server.
If setting SNTPPSIP is set to a specific IP address while setting ESNTP =
Table 7.4 Sett i n g s A ssociate d With SNTP
Setting Range Description
ESNTP UNICAST,
MANYCAST,
BROADCAST
Selects the mode of operation of SNTP. See
descriptions in SNTP Operation Modes on page 7.13.
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 required.
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.