ProSoft Technology MVI56-104S - Manual (Page 30)

MVI56-104S ♦ ControlLogix Platform Configuring the MVI56-104S Module
IEC 60870-5-104 Server Communication Module User Manual
Page 30 of 188
ProSoft Technology, Inc.
November 18, 2009
2.3 [SNTP CLIENT]
The [SNTP CLIENT] section of the CFG file is used to specify the parameters for
the Simple Network Time Protocol (SNTP) client provided with the protocol
driver. This client is required in order to keep the driver's internal clock set
correctly. This version of the driver supports SNTP Revision 3 and stratum
between 1 and 14.
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 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 by searching the
World Wide Web for "NTP Servers".