What if the network fails?


#1

Say I have a controller connected via a V-LAN to a computer. It is a SNAP-PAC controller. It could be a PAC-R1, S1, or S2. Opto Display is set up to log a certain measurement into a file that is sent to a network drive. The computer where OptoDisplay resides is connected to the plant network that has access to network drives. The controller does not. I have observed that when the network fails, OptoDisplay logs data in the project folder. Is there a way to automatically send the locally logged data to the desired network location when the network comes back? Even if the controller has to be connected to the plant network, I’ve been thinking about “pinging” the network drive from the controller by creating a dummy file there, but as to determine what should be sent to the network drive when the network gets fixed, I’m at a loss.


#2

Hi Freddie,

A little outside the scope of Opto gear, but interesting none the less…

PAC Display, like all Windows programs, simply makes calls to the OS to do any reads and writes to any drives.
Its the OS that we need to take a look at.
You dont mention what version of Windows you are using, not sure how much that matters, but I did a bit of Google Foo on the topic and it seems that Win 7 has a timeout value that you can tweak for networked drives. This timer sets how long unused shared drives will hang in there before they are disconnected.
I also read that Win 7 will automatically try and reconnect them as soon as the drive is used again.
Sounds like in your case, the network goes down for more than a few minutes and it will not reconnect.

How do you get the drives to reconnect once the network comes up?
Do you reboot the PC, or run a batch job?
If a batch job will reconnect, then you could look at some batch job glue to test the network drive via ping, if its down, keep pinging, once its back up, reconnect the drive and then grab the date time stamp of the files on the local drive and the remote drive and send up the files that are missing.
Yes, it will be a pretty solid batch file, but I don’t think its outside the realm of doable.

Do your IT guys have any thoughts on the matter?
They often have cool little utility programs for just this sort of thing in their back pocket (in the form of a USB drive).

I see why you are thinking of off loading it to the controller, but given you have a PC in the mix, I would focus my energy there and put it to work since it has the file and the network drive connectivity (When the network is up).

Ben.


#3

I’m using Windows 7. My concern is not reconnecting to the network drive, Windows does that on its own. When the network fails though, PAC Display will log the data in the local project folder. What I would like to do is if the network comes back, take the data that was logged locally and push it out to the network drive. Is this possible? Is it better if I just log everything using the controller itself?