Configuration and operation
5.9 Time-of-day synchronization
Procedure for time-of-day synchronization
The CP supports the three methods of time-of-day synchronization:
● Time from partner
In this case, the time of day is synchronized by the operation center. This method is
enabled automatically if the Plant Cloud Communication and Security functions are
enabled in "Communication types" in STEP 7.
To be able to receive the time of day from the operation center, "Operation center" and
"Operation centers" need to be fully configured.
● NTP or NTP (secure)
If Plant Cloud Communication is disabled, the time of day can only be synchronized using
NTP or NTP (secure). Here, configure the synchronization mode, the local time zone of
the station, the synchronization interval and the addresses of the NTP servers.
Special feature of time-of-day synchronization using NTP
If the "Accept time from non-synchronized NTP servers" option is enabled, the CP also
accepts the time from NTP servers that are not directly synchronized with stratum 16.
If the option is disabled, the response is as follows:
If the CP receives a time of day frame from an unsynchronized NTP server with stratum
16, the time of day is not set according to the frame. In this case, none of the NTP
servers is displayed as "NTP master" in the diagnostics; but rather only as being
NTP (secure) with security functions enabled
In the extended NTP configuration, you can create and manage additional NTP servers
including those of the type NTP (secure).
The secure method NTP (secure) uses authentication with symmetrical keys according to
the hash algorithms MD5 or SHA-1.
Ensuring a valid time of day
If you use security functions, a valid time of day is extremely important. It is recommended to
use the NTP (secure) method.
For information on configuration, refer to the STEP 7 online help of the "Time-of-day
synchronization" parameter group.
Operating Instructions, 02/2015, C79000-G8976-C384-01
CP 1243-1 PCC