Siemens SIMATIC NET TeleControl S7-1200 CP 1243-1 Operating Instructions Manual page 51

Configuration with the CP
Selection of the synchronization method
Depending on the configured communication types and security functions, time-of-day
synchronization is configured differently:
● Telecontrol communication enabled
With telecontrol communication enabled, the time of day of the CP is synchronized
automatically by the TCSB computer.
– Security functions enabled:
● Telecontrol communication not enabled
The time of day of the CP can only be synchronized with NTP mechanisms:
– Security functions enabled:
– Security functions not enabled:
If no time of day synchronization is enabled on the CP, the CP can take the time from the
CPU (see below).
Parameter
● NTP (secure) with security functions enabled
If you use security functions, a valid time of day is extremely important. It is
recommended to use the NTP (secure) method.
The secure method NTP (secure) uses symmetrical keys according to the hash
algorithms MD5 or SHA-1.
In the global security settings of the STEP 7 project, you can create and manage
additional NTP servers also of the type NTP (secure).
● "Accept time from non-synchronized NTP servers" option
If the option is enabled, the CP also accepts the time-of-day from non-synchronized NTP
servers with stratum ≥ 15.
If the option is disabled, the CP does not accept the time-of-day from NTP servers with
stratum ≥ 15.
For more information on configuration, refer to the STEP 7 online help of the "Time
synchronization" parameter group.
CP 1243-1
Operating Instructions, 12/2016, C79000-G8976-C365-02
The time-of-day synchronization is configured in the "Security" parameter group.
The time-of-day synchronization is configured in the "Security" parameter group. NTP
and NTP (secure) are available as the synchronization methods.
The time-of-day synchronization is configured in the "Ethernet interface > Time
synchronization" parameter group. Only NTP is available as the synchronization
method.
Configuration
4.8 Security
51