GE C30 Instruction Manual page 178

5.2 PRODUCT SETUP
PORT 1 ... 3 FUNCTION
• While this port setting is selected to disabled, PTP is disabled on this port. The relay does not generate or listen to
PTP messages on this port.
PORT 1 ... 3 PATH DELAY ADDER
• The time delivered by PTP is advanced by the time value in this setting prior to the time being used to synchronize the
relay's real time clock. This is to compensate to the extent practical for time delivery delays not compensated for in the
network. In a fully compliant PP network, the peer delay and the processing delay mechanisms compensate for all the
delays between the grandmaster and the relay. In such networks, this setting should be zero.
• In networks containing one or more switches and/or clocks that do not implement both of these mechanisms, not all
delays are compensated, so the time of message arrival at the relay will be later than the time indicated in the mes-
sage. This setting can be used to approximately compensate for this delay. However, as the relay is not aware of net-
work switching that dynamically changes the amount of uncompensated delay, there is no setting that will always
completely correct for uncompensated delay. A setting can be chosen that will reduce worst-case error to half of the
range between minimum and maximum uncompensated delay, if these values are known.
PORT 1 ... 3 PATH DELAY ASYMMETRY
• This setting corresponds to "delayAsymmetry" in PTP, which is used by the peer delay mechanism to compensate for
any difference in the propagation delay between the two directions of a link. Except in unusual cases, the two fibers are
of essentially identical length and composition, so this setting should be set to zero.
• In unusual cases where the length of the link is different in different directions, this setting should be set to the number
of nanoseconds the Ethernet propagation delay to the relay is longer than the mean of path propagation delays to and
from the relay. For instance, if it is known say from the physical length of the fibers and the propagation speed in the
fibers that the delay from the relay to the Ethernet switch it is connected to is 9 000 ns and the that the delay from the
5
switch to the relay is 11 000 ns, then the mean delay is 10 000 ns, and the path delay asymmetry is 11000 - 10000 =
+1000 ns.
c) SNTP PROTOCOL

PATH: SETTINGS PRODUCT SETUP
 SNTP PROTOCOL

The C30 supports the Simple Network Time Protocol specified in RFC-2030. With SNTP, the C30 can obtain clock time
over an Ethernet network. The C30 acts as an SNTP client to receive time values from an SNTP/NTP server, usually a ded-
icated product using a GPS receiver to provide an accurate time. UR series relays support unicast, broadcast, multicast,
and anycast SNTP functionality.
The setting enables or disabled the SNTP feature on the C30.
SNTP FUNCTION
To use SNTP in unicast mode,
set and
SNTP FUNCTION
values are obtained and averaged, it generally takes three to four minutes until the C30 clock is closely synchronized with
the SNTP/NTP server. It takes up to two minutes for the C30 to signal an SNTP self-test error if the server is offline.
To use SNTP in broadcast mode, set the
C30 then listens to SNTP messages sent to the "all ones" broadcast address for the subnet. The C30 waits up to 18 min-
utes (>1024 seconds) without receiving an SNTP broadcast message before signaling an SNTP self-test error.
The
SNTP UDP PORT NUMBER
When the
SNTP UDP PORT NUMBER
NOTE
5-58

REAL TIME CLOCK
SNTP FUNCTION:
Disabled
SNTP SERVER IP ADDR:
MESSAGE
0.0.0.0
SNTP UDP PORT
MESSAGE
NUMBER: 123
SNTP SERVER IP ADDR
is "Enabled," the C30 attempts to obtain time values from the SNTP/NTP server. Since many time
SNTP SERVER IP ADDR
is 123 for normal SNTP operation. If SNTP is not required, close the port by setting it to 0.
is set to 0, the change takes effect when the C30 is restarted.
C30 Controller System

SNTP PROTOCOL
Range: Enabled, Disabled
Range: Standard IP address format
Range: 0 to 65535 in steps of 1
must be set to the SNTP/NTP server IP address. Once this address is
setting to "0.0.0.0" and
5 SETTINGS
to "Enabled." The
SNTP FUNCTION
GE Multilin