WCCILevent - SYS/SEVERE - MsgQueueContainer, appendMsg, MSG Limit exceeded - Over the limit 100000 for connection

Enclosed you'll find the explanation for a combination of log-messages which can occur during runtime. The log-message is written to the PVSS_II.log-file.

WCCILevent (0), 2021.11.21 11:43:55.042, SYS, SEVERE, 54, Unexpected state, MsgQueueContainer, appendMsg, MSG Limit exceeded - Over the limit 100000 for connection (SYS: 1 Ctrl -num 2 CONN: 1)!Current queuesize: 113679

WCCILevent (0), 2021.11.21 11:44:02.513, SYS, INFO, 54, Unexpected state, MsgQueueContainer, appendMsg, MSG Limit exceeded - Going below message limit 100000 for connection (SYS: 1 Ctrl -num 2 CONN: 1)

Log-message with symbolic names:

WCCILevent (0), <TIMESTAMP>, SYS, SEVERE, 54, Unexpected state, MsgQueueContainer, appendMsg, MSG Limit exceeded - Over the limit <current limit> for connection (SYS: <systemnumber> <manager-ID> -num <manager-number> CONN: <connection>)!Current queuesize: <queuesize>

WCCILevent (0), <TIMESTAMP>, SYS, INFO, 54, Unexpected state, MsgQueueContainer, appendMsg, MSG Limit exceeded - Going below message limit <current limit> for connection (SYS: <systemnumber> <manager-ID> -num <manager-number> CONN: <connection>)

This log-message describes that the current limit for the message-queue in receive direction was exceeded. The current value for the queuesize is written at the keyword <queuesize>. For which connection the limit was exceeded can be seen at the keywords <manager-ID> and <manager-number>.
If the queuesize is going below the given limit within a defined timespan you’ll see the second log-message, otherwise the connection to the specific manager will be closed.
The queuesize and the timeout can be defined with the config-entries maxInputMsgCount and msgQueueLimitTimeout for the Event Manager.

For further details please have a look at the WinCC OA Documentation and search for the keywords “Error tolerance” and “stability”.