Applies To:
  • CitectSCADA 4.10 4.20

I am running my Citect server on a Windows NT server computer. The computer is operating as a Citect Trend/Report/Alarm and I/O Server as well as being the network file server. When I run the tape backup utility on the File server the performance of Citect is degraded and I occasionally get time out errors to the PLC's. I assume that the tape backup software is using too much CPU, is there a solution to this problem? 

The Citect server and client run at NORMAL_PRIORITY_CLASS which is the default priority for processes under Windows NT and Windows 95. From your description of the problem it appears that the tape backup utility is also running at this or higher priority class and starving Citect of the CPU it needs. You can increase the priority class of a Citect Server to HIGH_PRIORITY_CLASS by setting the following parameter in the CITECT.INI file:


If the computer is only running as a Citect client then this parameter is ignored and Citect will run at NORMAL_PRIORITY_CLASS.

WARNING: You must be careful when setting this parameter as Citect will run at such a high priority that Citect may starve other processes in the same computer. Before setting this parameter you should check how much CPU Citect is using, typical projects should be between 0 to 40%. If the CPU loading is very high or 100% then it could be caused by incorrect configuration, see Q1805 for details of CPU overloading. If Citect CPU usage is typically below 40% then there should be no problem with setting this parameter.