Rockwell Automation 1756-HIST2G Historian ME 2.1 - Manual (Page 136)

F ACTORY T ALK H ISTORIAN ME M ODULE U SER ’ S G UIDE
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Time Synchronization Settings
The FactoryTalk Historian ME can periodically check external time sources to
synchronize its time settings. Synchronization is based on a single selected time
source that coordinates time accuracy among different devices in your FactoryTalk
environment. The module’s Universal Coordinated Time (UTC) may be
synchronized to a Logix5000 Controller, a network NTP time server, or a FactoryTalk
Historian SE configured as an NTP time server.
For NTP Server or FactoryTalk Historian SE time synchronization options, the
module obtains the current time for its real-time clock once per minute. The module
uses its real-time clock and periodically corrects the clock drift using its NTP Server
or Controller Time.
To synchronize time in the FactoryTalk Historian ME, select one of four options:

Controller Time
Select the Controller Time radio button, and then select a controller from the
drop-down menu.
Take appropriate precautions when changing the module time to a past time
compared to the current module time. If you perform this operation, the following
message displays, “The time you have entered is in the past, This may put the module
in safe mode, which would require you to delete all data archives past this time. Are
you sure you want to continue?”
If you click [Yes] the module will enter safe mode if the time change results in 1)
archive file timestamps are newer than the module’s current time or 2) archive files
with overlapping time ranges. If the module enters safe mode, go to the Web
Diagnostics interface to repair the archive files and exit safe mode.
Select one of four
Time Synchronization
options