PC-based Automation
WinXP embedded, flash disks, EWF and datalogging.
Thread Starter: Jesper Pedersen Started: 2/26/2009 4:11 PM Replies: 5
2/26/2009, 4:11 PM
|
Joined 7/28/2006
Last visit: 3/21/2011
Posts: 279
Rating:
![Rated: Outstanding [3.57 out of 5 / rated 30 time(s)].](/forum/Skins/images/Star4.user.gif) (30)
|
![Rated: no ratings [0 out of 5 / rated 0 time(s)].](/forum/Skins/images/Star0.post.gif) (0)
|
Hi there.
I am investigating the possibilities of using an IPC in connection with WinAC RTX and/or WinCC Flexible RT.
The IPC could be a Microbox 427B or a panel PC 477B, both have WinXP embedded and no normal harddrive, only flash drives (*).
As far as I understand, the Enhanced Write Filter (EWF) is critical when flash drives are used in stead of normal harddrives.
The question is then what this will mean for the eventual datalogging that we have with WinCC Flex RT.
Is it required that Windows is shutdown before turning off the IPC, otherwise data will be lost ?
Will it be necessary to install a UPS ?
Is it possible to detect a power-off and automatically initiate a shutdown of Windows ?
Or are there other methods to avoid losing data due to EWF ?
Thanks for any insight into the matter.
*: Even if a normal harddrive would be possible, one reason for switching to one of these IPCs is exactly to avoid the normal harddrive.
|
|
|
|
2/26/2009, 6:36 PM
|
Joined 5/19/2006
Last visit: 5/20/2013
Posts: 524
Rating:
![Rated: Excellent [4.29 out of 5 / rated 77 time(s)].](/forum/Skins/images/Star4Half.user.gif) (77)
|
|
(0)
|
Hi,
I am not sure if I understood your concerns about EWF.
With XPE, EWF is designed to protect CF partitions from writing so all write access are done over an overlay RAM. When you reboot those changes are lost.
The advantage here is to save the flash live time over a regular HD where number of write access is not a n issue.
You can configure what partitions you want to protect with EWF.
With WinCCFlex data logging why can't you configure the path on a network share so you don't lose your data if you lose the power and in the same time have your IPC flash protected?
Dec
|
|
|
|
2/27/2009, 8:21 AM
|
Joined 7/28/2006
Last visit: 3/21/2011
Posts: 279
Rating:
(30)
|
|
(0)
|
Hi dec.
I am aware of the reason for EWF.
What I am concerned of is what happens when a machine is shutdown,
You cannot expect operators to first shutdown windows, wait some time and then shut off power. It is not realistic.
Surely I cannot be the first with these thoughts.
Logging to a network drive could be a solution. But it is not possible in most of my installations.
What about this:
Will it be necessary to install a UPS ?
Is it possible to detect a power-off and automatically initiate a shutdown of Windows ?
Or are there other methods to avoid losing data due to EWF ?
|
|
|
|
2/27/2009, 9:17 AM
|
Joined 7/28/2006
Last visit: 3/21/2011
Posts: 279
Rating:
(30)
|
|
(0)
|
Another thought just struck me.
Since a machine can run 24/7 for a very long time without shutdown, and since EWF redirects disk writes to RAM, RAM memory will slowly be used up. So it cannot go on forever.
Somehow it must be possible to write the data to disk cyclically.
I know there is something called "live commit" with EWF. Is it possible to automatically commit the data to flash disk, say every hour or so ?
So many questions. But they have to be answered, or I will become unpopular by certain people if there are unpleasant surprises from taking this jump.
|
|
|
|
3/2/2009, 12:12 PM
|
Joined 11/15/2006
Last visit: 5/14/2013
Posts: 941
Rating:
(106)
|
|
(0)
|
Will it be necessary to install a UPS ?
Is it possible to detect a power-off and automatically initiate a shutdown of Windows ?
If you use an UPS the UPS detect the power loss and can send a signal to windows. If you have a better one, those can run a batch file or an application, the mustn't shut down the PC immediately. There you can run a batch-file which shuts down the PC after doing some other action, for example shuting down other services.
Have Fun!
TomDeWou
|
|
|
|
4/5/2009, 4:25 PM
|
Joined 4/3/2008
Last visit: 9/5/2012
Posts: 62
Rating:
![Rated: no ratings [0 out of 5 / rated 0 time(s)].](/forum/Skins/images/Star0.user.gif) (0)
|
|
(0)
|
I just want to add my experiences with EWF:
I have installed some machines with PC477 embedded and C drive filtered where Wincc flex 2005 keep on writing down recipes and archive. D drive (just 128Kb) has been released to get free of filter for temporary files as shared document.
Those machines has been installed in a Country where any time there is a cloud around 50 Km there is a power brake down and the machine has no UPS.
So the worst condition: a 24/7 working machine with a lot of power brakedown and no IT manager around the factory but just simple maintenance electricians.
The result is that I never face any problem.
Thank you WinXP embedded and thank you EWF.
pigroplc
|
|
|
|
Actions
Print