Media Redundancy; Time-Of-Day Synchronization - Siemens CM 1542-1 Operating Instructions Manual

4.4

Media redundancy

You can use the CM in a ring topology with media redundancy.
For more detailed information on configuration, refer to the STEP 7 online help of the "Media
redundancy" parameter group.
4.5

Time-of-day synchronization

Note
Recommendation for setting the time
Synchronization with a external clock at intervals of approximately 10 seconds is
recommended. This achieves as small a deviation as possible between the internal time and
the absolute time.
Procedure
The CM supports the following mode for time-of-day synchronization:
● NTP (NTP: Network Time Protocol)
Configuration
For information on configuration, refer to the STEP 7 online help of the "Time-of-day
synchronization" parameter group.
● Accept time of day from non-synchronized NTP servers
The paramter has the following effect:
– If the option is enabled, the CP also accepts the time-of-day from non-synchronized
– If the option is disabled, the response is as follows: If the CP receives a time of day
CM 1542-1
Operating Instructions, 07/2019, C79000-G8976-C355-04
NTP servers with stratum 16.
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".
Configuration, programming
4.4 Media redundancy
33