Siemens S7-1200 Operating Instructions Manual page 65

Configuration
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:
For more information on configuration, refer to the STEP 7 online help of the "Time
synchronization" parameter group.
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 authentication with symmetrical keys according to
the hash algorithms MD5 or SHA-1.
You can create and manage additional NTP servers also of the type NTP (secure) in the
global Security settings of the STEP 7 project.
"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 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 "reachable".
Time-of-day synchronization of the CPU
In the parameter group "Communication with the CPU", you can set whether or not the
current time of day of the CP will be made available to the CPU via a PLC tag.
CP 1243-7 LTE
Operating Instructions, 01/2015, C79000-G8976-C381-01
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 and operation
4.14 Time-of-day synchronization
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