WinCC OA-managers - SYS/SEVERE - Send buffer limit exceeded, closing connection to “connection”
Enclosed you'll find the explanation for a log-message which can occur during startup of the project or during runtime. The log-message is written to the PVSS_II.log-file.
PVSS00<manager> (0), 2012.05.31 14:22:11.667, SYS, SEVERE, 39, Connection lost, Send buffer limit exceeded, closing connection to (SYS: 1 Driver -num 1 CONN: 1) @ PVSSRDB1, [PeerItcIOHandler::sendCall]
Log-message with symbolic names:
PVSS00< manager> (0), <TIMESTAMP>, SYS, SEVERE, 39, Connection lost, Send buffer limit exceeded, closing connection to (SYS: <system-number> <manager-name> -num <manager-number> CONN: 1) @ <hostname>, [PeerItcIOHandler::sendCall]
This log-message describes that the event-manager has closed the connection to the given <manager-name> + <manager-number> running at the host <hostname>.
The connection was closed because the limit for the send buffer was reached.
The settings for the send buffer can be modified with the following config-entries:
maxBcmBufferSize
bcmBufferLimitTimeout
For detailed information concerning the config-entries please have a look at the online-help and search for these words.
This functionality is not only used at the event-manager, all WinCC OA-processes use these safety-functionality.
Possible causes for this behaviour are:
-- high amount of data within a short time
-- low speed network-connection
-- high workload at the WinCC OA processes for a long time
-- blocking WinCC OA-processes
If the log-messages occurs several times please have a look at the WinCC OA logfiles at the first step to see which connections are affected if there some sort of “repeated behaviour”, e.g. the problem occurs every day at 02:00 o’clock.
To find the cause for it or additional information you could also use the following functionalities:
-- tools to trace the CPU-/memory-usage for the system, especially the WinCC OA processes (Windows: Performance Monitor, Linux: top)
-- “dispatch”-information for the WinCC OA processes: With the debug-flag “-report dispatch” set for a WinCC OA process you get once the information which connections are established and how many data is processed and pending in the input/output-buffers. If the debug-flag is set several times in a given time-intervall, e.g. every 3 minutes you can detect If the buffersize increases for one or several connections is increasing
-- “-dbg msg_statistic” information: With the debug-flag “-dbg msg_statistic” you get the information which messages are send/received within a given time interval. With this information you can detect if one process might send to much data. To get detailed information please have a look at the online help: System Managerment --> Diagnostics --> WinCC OA diagnostics
If you need further assistance please get in contact with your common WinCC OA support.