Siemens 9810 Series, Руководство пользователя, Страница: 176 / 218

Time and timekeeping
The meter clock is synchronized to an external time sync source. Use this for the
Clock Source if:
• The Time Sync Source setup register is set to a serial communications port to
receive GPS time synchronization signals.
• The Time Sync Source setup register is set to
ETHERNET
-
PTP
and your meter is
installed in a trusted PTP network.
• The Time Sync Source setup register is set to
IRIG
-
B
.
Clock source time quality flag
The meter’s clock source time quality flag is primarily used to report time quality
information for digital input events, such as status alarms, in Sequence-of-Events
Recording (SER) applications.
The meter keeps track of the time difference between the meter’s internal clock
and the time sync source.
When the meter’s Clock module’s Use Clock Source Qual Flag is set to
USE FLAG
,
the Diagnostics module’s Receiver Status output register is set to:
•
LOCKED
if the time difference between the GPS time sync source or PTP
master and meter clock is within ±1 ms of each other
•
UNLOCKED
if the time difference between the GPS time sync source or PTP
master and meter clock is greater than ±1 ms of each other
PTP system setting recommendations
Your meter has been configured by default to be compatible in typical PTP
supported systems.
In a PTP system, the grandmaster clock determines the reference time for the
entire system. To ensure correct implementation and operation of the protocol, it is
recommended to set the following parameters in your system grandmaster clock:
Parameter Setting Description
PTP device type End to End transparent clock A transparent clock that
supports the use of the end-to-
end delay measurement
mechanism between slave
clocks and the master clock.
Peer delay mechanism 2 step A clock that provides time
information using the
combination of an event
message and a subsequent
general message.
Clock domain 0-3 A logical grouping of clocks
that synchronize to each other
using the protocol, but that are
not necessarily synchronized
to clocks in another domain
Ethernet switches PTP compatible All switches and other devices
in the network must support
IEEE 1588 PTP to achieve the
stated time precision and
accuracy
Star network topology
In addition to PTP system related settings, the accuracy of your meter clock also
depends on your physical network configuration. A star network topology is
required to achieve the level of clock precision specified.
176 7EN05-0390-00