ProSoft Technology 5201-DFNT-104S - Manual (Page 123)

Reference 104S v2 ♦ ProLinx Gateway
Protocol Manual (Firmware v2.xx)
ProSoft Technology, Inc.
Page 123 of 157
March 19, 2010
5.3 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 gateway’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.
5.3.1 SNTP Status Data
The status data for the SNTP driver is located at the virtual database addresses
shown in the following table. The data area is initialized with zeros whenever the
gateway is initialized. This occurs during a cold-start (power-on), reset (reset
push-button pressed) or warm-boot operation (commanded or loading of new
configuration).
SNTP Client Status
4030 Time is valid
4031 Request count
4032 Response count
4033 Computation count
4034 Clock set count
4035 Timeout error count
The gateway’s data mapping feature can be utilized to move this data into the
gateway’s database area. This way the data can be made available to all drivers
on the gateway for use on any of the connected networks. If it is not mapped into
the gateway’s database, the data will only be available through the
Configuration/Debug Port.
The Time is Valid status register will be set to 1 if the SNTP time is valid. If the
time is not valid, the register will be set to 0. All the other registers are counters
used to determine the functionality of the driver.
This version of the driver supports SNTP Revision 3 and stratum between 1 and
14.