Applies To:
  • CitectSCADA 4.00 4.10

If you have LAN redundancy installed and you get a network failure Citect will change over to the second LAN, however Citect may GPF a short time later. 

This problem is caused because you have Citect installed on the network file server. If you install Citect on the local hard disk this problem will not occur. This will only occur with version 4.x when running under Windows 95 or Window NT. Version 3.x running under WFW or Windows 95 does not show this problem.

More Information

When you startup any Win32 application under Windows 95 or Windows NT that application is not totally loaded into memory. Windows will load a small part of the program into memory and start executing it. When the application needs to execute code or access data which has not been loaded into memory yet, Windows will load it. This is done to give faster startup times for applications and to reduce memory usage. When memory is become overloaded Windows will also unload sections of the program code or write the program data to the swap file. This is part of the normal windows memory paging system.

So if you are running any application from a network file server and you break the link to the file server, Windows will not be able to load any more of the application. This should cause a fatal system error, however under Windows 95 and Windows NT 3.x it will cause the application to generate a In Page Error. The only solution is to install the application on the local hard disk.

This was not a problem with Citect version 3.x under Windows as Citect would force Windows to load the entire application at startup. CIT has confirmed this to be a problem in Citect for Windows 4.00 and 4.10. We are researching this problem and will post new information here as it becomes available.