Reference
Configuration of the time-of-day synchronization method of the module in the parameter group "Time-of-day synchronization" under the PROFINET interface or in the Security settings.
For time-of-day synchronization of the S7-1200, see section Time-of-day synchronization with S7-1200.
For configuration of the time-of-day synchronization of the IE/PB Link PN IO (V3) see section Time-of-day synchronization - IE/PB LINK PN IO (V3).
How the time synchronization modes work
-
SIMATIC mode
If the SIMATIC mode is enabled, the module sets its time-of-day according to MMS time-of-day messages (MMS ‑ Manufacturing Message Specifaction).
The MMS time-of-day messages originate from a SIMATIC time transmitter or a CPU configured as time master. The time-of-day messages can be received by the module (e.g. CP) either from the local CPU or via a LAN. It is possible to set whether the module will forward the received time of day.
The advantage of the SIMATIC mode is that it is generally more accurate than the NTP mode.
See also SIMATIC mode - configuration
-
NTP method
(NTP ‑ Network Time Protocol)
With the NTP method, the module sends time-of-day queries to one or more NTP servers in the subnet (LAN). Based on the replies from the server, the most reliable and most accurate time is determined and the time of day on the querying module is synchronized. In this case, any MMS time messages that are received will be ignored.
In NTP mode, it is generally UTC (Universal Time Coordinated) that is transferred. This corresponds to GMT (Greenwich Mean Time).
The advantage of NTP mode is that it allows the time to be synchronized across subnets.
See also NTP method - configuration