User manual

Using the NTPTime Service
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33002479 06 07/2008
Introducing the NTP Time Synchronization Service
General The NTP time service synchronizes computer clocks over the Internet. For example,
the time of one client is synchronized either with another server or to a referenced
time source like a radio or satellite receiver.
Typical time service configurations utilize redundant servers and diverse network
paths to achieve high accuracy and reliability. Time service accuracy can be within
a millisecond on LANs and up to a few tenths of milliseconds on WANs.
Use the time service for:
z event recording (sequence events)
z event synchronization (trigger simultaneous events)
z alarm and I/O synchronization (time stamp alarms)
Features of the
NTP Time
Service
Some features of the NTP time synchronization service are:
z periodic time correction obtained from the reference-standard time server
z automatic switch over to a backup time server if a problem occurs with the normal
time server system
z controller projects use a function block to read the accurate clock, a feature that
allows project events or variables to be time stamped
z estimated time stamping accuracy of:
z 5 mSec for 140 CPU 651 x0’s and higher
z 10 mSec for other CPUs
z local time zone is configurable and customizable including daylight savings time
z Web page diagnostics for the time synchronization service