Applies To:
  • CitectSCADA 5.xx, 6.00
  • CitectHMI 5.xx, 6.00

My alarm server CPU usage increases significantly when display clients are attached. I have 26 display clients and other Internet Manager Clients. The Alarm server is not used for display and the CPU increases even when the display clients do not display alarm banners and alarm pages. The project has some 60,000 digital alarms and the mimic pages make extensive use of alarm tag properties for object animation.

To investigate the CPU usage and performance, I opened the Citect Kernel. I ran "Page Table Stats" and noticed that the "Get Alarm" task count, max and other values increased when clients were attached. Can you explain?


The "Get Alarm" task checks the dynamic alarm properties. If you have large numbers of active alarm tag properties on your graphics pages then this task will increase and increase CPU usage.

The [Alarm]Active parameter can be used if necessary to alleviate CPU load.

[Alarm]Active defines the period (in milliseconds) at which the display clients are advised of a change in alarms. For example, if [Alarm}Active is set to 1000 (default), the display clients are advised every 1 second (if a change has occurred in the alarms held on the Alarms Server). This can be set up to a maximum of 10000.

Note, if you are using a large number of string tags in alarm description fields it can also increase the CPU load.

See also Q1060.