Siemens CP 1243-1 Operating Instructions Manual page 43

The CP supports the following methods of time-of-day synchronization:
● Time from partner
The CP adopts the time-of-day from the communications partner in the master station.
Only when telecontrol communication is enabled.
● NTP
The time of day is synchronized by an NTP server in the connected network.
The method can also be used when the telecontrol communication is enabled.
With CPs as of firmware version V3, the address of the NTP server can also be entered
as a URL, e.g. <ntp.server.com>. For this a DNS server is required.
● NTP (secure)
The secure method NTP (secure) uses symmetrical keys according to the hash
algorithms MD5 or SHA-1.
On the CP you specify the servers used.
You configure NTP servers of the type NTP (secure) in the global security settings of
STEP 7.
● Time from the CPU
As of V4.2, the CPU synchronizes all CMs/CPs of the station with a synchronization cycle
of 10 seconds.
Parameters of the CPU:
If for the CPU the option "CPU synchronizes the modules of the device" is enabled, all
smart modules of the station (CPs with of firmware ≥ V2.1.77) are synchronized with the
CPU time in a synchronization cycle of 10 seconds.
Parameter groups for time-of-day synchronization
You can configure time-of-day synchronization in the following parameter groups:
● Ethernet interface
Here you create the configuration under the following conditions:
– Telecontrol communication is disabled.
– The security functions are disabled.
● Security
Here you create the configuration under the following condition:
– The security functions are enabled.
CP 1243-1
Operating Instructions, 04/2017, C79000-G8976-C365-03
Configuration
4.4 Time-of-day synchronization
43