Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 2.00, 2.01

You should always have enough memory so that Citect will run in true physical memory and not require virtual memory. If there is not enough physical memory, Windows will start to use virtual (disk based) memory. When this starts to happen the performance of Citect will degrade and may cause I/O Servers to crash.

This is especially important for Citect Servers as they require more memory, do a lot of memory processing, and effect the performance of the entire network.

It is OK for Citect to use Virtual memory under infrequent peak loading conditions, so you should enable virtual memory. However to get good real time response you should have enough memory available.

You can tell if Citect is running out of physical memory by looking at the memory free in the Window Program manager About Dialog, and the size of you virtual memory file (in the control panel, 386 Enhances, Virtual Memory). The memory free should be greater than the size of the virtual memory file. If it is less then you should buy memory to fill the gap. For example:

Memory free Virtual file size True free physical memory
10,000 kb 8,196 kb 1,804 kb
7,000 kb 8,196 kb -1,196 ! memory shortage, add 2Mb

If you are using a temporary swap file, the size of the virtual memory file will change with Windows needs. Because of this, the above calculation of free physical memory will be unreliable. Change to a permanent swap file and then check for free physical memory. As a permanent swap file gives better performance, you should always use a permanent swap file. The swap file should not be bigger than 8,196 Kb, because if all this virtual memory was being used, the performance of Citect would be seriously degraded. 

If you are running out of memory, reduce the memory usage, eg reduce the size of SMARTDRIVE cache size or any other program consuming memory. Reduce the size of the Citect database records, eg alarms, trends, reports, Cicode (number of pages does not effect memory usage only the sizes of the pages currently displayed).

The best Solution is to buy more memory, memory is cheap!