Extended device functions
5.2 Enhanced Write Filter
SIMATIC IPC427D
Operating Instructions, 05/2017, A5E31347215-AB
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Special features for the use of Enhanced Write Filters (EWF)
●
In the event of a power failure, if the EWF is enabled changes made after the boot
sequence on drive C: are lost.
To prevent data loss in the event of a power failure, the use of a UPS is recommended.
●
You can save the data in the EWF RAM overlay to the CFast card or the hard disk before
you shut down the device. To do so, enter the following command in the command
prompt:
ewfmgr c: -commit
Note
When the system is set to automatically adjust the clock for daylight saving time adjustment,
systems without central time management and with activated EWF set the clock forward or
backward by one hour in the daylight saving time or standard time period each time the
system boots.
The reason for this behavior is that Windows Embedded Standard 7 makes a registry entry
that the changeover to daylight saving time has occurred. Since this file is also protected
against modification by the EWF, the marker is lost during the boot sequence and the
adjustment is made again.
We therefore recommend that you deactivate the automatic adjustment and change the
clock manually.
Procedure:
1.
Deactivate automatic adjustment in the Control Panel. In the Time Zone tab opened with
the menu command Start > Control Panel > Date and Time, remove the check mark from
the "Automatically adjust clock for daylight saving changes" check box.
2.
Save the change you have made with
ewfmgr c: -commit
and then reboot the system.
