Applies To:
  • CitectSCADA 5.xx

Citect may run out of kernel queues and shutdown under the following conditions: Several IDC clients try to connect to a Proxi server, which already has connections defined to around 30 IOServers. The problem results from Citect running out of network session structures. Why is this?

CIT has confirmed this to be a problem in Citect for Windows versions 5.xx.  This problem has been fixed in Citect version 5.21 Service Pack E.  The maximum number of network session structures has been increased from 255 to 4000.  However it will be impossible to use more than 255 sessions unless Citect is configured to use pure TCPIP sockets connections, rather than Netbios based connections.  The default number of kernel queues has also been increased from 512 to 1000. This is the


parameter in the Citect.ini file.  Please check Citect Help for the version of Citect you are running to see if [Kernel]Queue is increased to another value.