ProSoft Technology MVI56-104S - Manual (Page 151)

Reference MVI56-104S ♦ ControlLogix Platform
User Manual IEC 60870-5-104 Server Communication Module
ProSoft Technology, Inc.
Page 151 of 188
November 18, 2009
5.3.6 SNTP Support
SNTP is used for time synchronization of produced and consumed commands.
When an exchange occurs the driver compares time stamps from the previous
exchange. When the new exchange time is less than the previous exchange, the
exchange is ignored. This can occur when the Ethernet packets are routed and
delayed. Time synchronization provides for data integrity. The following table lists
the parameters defined in this section:
The SNTP driver will compute a new clock value every 5 minutes using the
average value of 10 samples each collected over an approximate 6-second
period. This new value will be used to adjust the clock maintained by the SNTP
driver and used by the application. If a valid database register is specified, the
driver will place the time value into the module’s database. The first two registers
will contain the number of seconds and the next two registers will contain the
number of microseconds since January 1, 1970.
A list of some of the common NTP servers can be obtained at
http://www.ntp.org/, http://www.eecis.udel.edu/~mills/ntp/servers.html, along with
the appropriate IP address. Other server lists can be found on the Internet by
searching on "NTP Servers" with your browser.