Siemens SIMATIC TIM 3V-IE DNP3 System Manual page 27

Time-of-day synchronization using DNP3 mechanisms
The system time of the station TIM can be set by a PC of the connected DNP3 master
station.
If the TIM module has established a connection to the DNP3 master station, the TIM module
requests time-of-day synchronization by the master station in the accompanying internal
indication bit "IIN1.4 [NEED_TIME]".
If the master station supports this function, it sends time-of-day messages with the time of
day to the TIM module. The TIM system time is set whenever a time-of-day message is
received.
Remember that the time of day of DNP3 master stations in UTC format generally does not
take into account daylight saving time or time zones.
To request a renewed time-of-day synchronization, the TIM sets the corresponding IIN1.4 bit
after a configurable time has elapsed since the last time-of-day synchronization. The
synchronization cycles are specified in the configuration.
Time-of-day synchronization with NTP
The time of day synchronization using NTP is only supported by the TIM 4R IE DNP3. It is
intended for the TIM as DNP3 master station.
The following use of the two Ethernet interfaces of the TIM 4R IE DNP3 is a practical
solution:
● One Ethernet interface for connecting the DNP3 network
● One Ethernet interface for connecting to one or two NTP servers
As a result, the two networks are separated from each other.
The TIM supports the following variants of NTP:
● NTP
time-of-day synchronization method without authentication
● NTP (secure)
The secure method NTP (secure) uses authentication with symmetrical keys according to
the hash algorithms MD5 or SHA-1.
Configuration
You configure time-of-day synchronization in STEP 7, refer to the section Configuring time-
of-day synchronization (Page 134).
TIM DNP3
System Manual, 12/2015, C79000-G8976-C253-04
Uses and properties of the TIM
1.9 Time synchronization
27