Time Synchronization; Function Description - Siemens SICAM 7KG85X Manual

2.4

Time Synchronization

Function Description

2.4.1
General
During operation, the device needs the date and time for all time-relevant processes. The term time is used
throughout this section to refer to both the date and the time.
The time synchronization in the device is necessary to guarantee a common time basis for the communication
with peripheral devices and time stamping of the process data.
The device supports both external and internal time synchronization. The type of time synchronization is
specified during the parameterization. The external time synchronization from an NTP server is preferred.
NOTE
i
i
The time format is described in detail in the RFC 5905 (Request for Comments 5905 for NTP).
Internal Time Keeping
Time Format
The internal time is kept in UTC (Universal Time Coordinated) from 01.01.2000, 00:00 to 31.12.2099, 23:59.
To display the local time, for example on the HTML pages, you can configure a local time correction factor and
the automatic adjustment to daylight saving time during parameterization.
FAIL Status Bit
The FAIL status bit implemented in the the device signals with 0 that the time is valid and with 1 that the time
is invalid.
The status of the FAIL bit corresponds to the Clock error operational indication, see chapter
Indications and Operating
The following table lists the time stamps of events or indications for the displayed operational, error, and audit
logs according to status bit set/not set using the example of date
Table 2-6
FAIL
0
1
DST Status Bit
With 1, the DST status bit implemented in the device signals that the local daylight saving time is active. The
operational indication Daylight saving time is displayed.
External Time Synchronization per NTP
General
To synchronize the time via an external source, the device is equipped with an SNTP Client (SNTP = Simple
Network Time Protocol) that can be connected to 2 NTP servers (NTP = Network Time Protocol), the primary
and the secondary (redundant) NTP server.
NTP is used for external time synchronization via Ethernet. The SNTP client sends a time request to the NTP
server once a minute. The time synchronization error is ±5 ms referred to UTC time of the NTP server.
The time stamp of the NTP server has a 64‑bit format. Counting is accomplished in seconds and fractions of
seconds.
SICAM, SICAM P850/P855 7KG85X, Manual
E50417-H1040-C482-A9, Edition 03.2022
Parameters.
FAIL Status Bit for Time Synchronization via NTP Server
Output
2016-09-26 13:49.35:246
2016-09-26 13?49?35?246
2.4 Time Synchronization
2016-09-26, time 13:49.35246 :
Basic Functions
13 Operational
41