OPC UA Connection Test Failure Over 500 Tags - Help

[DanielMurray]

Hi All,

I am currently testing the connection between WinCC OA and TIA Portal via OPC UA and experiencing issues.

WinCC OA: Version 3.15 P007
TIA Portal: Version 14
PLC: 1516-3 Version V2.0

Using a new WinCC OA project I connected equal number bools, ints and reals to tags in a new TIA Portal project. The tags in TIA were set to update every 100ms and the addresses within WinCC OA were set to poll every 1s.

With 500 total tags connected, each tag updates once per second within WinCC OA as expected.

However, with 600+ tags connected, I got the following error messages in the log viewer repeatedly and the tags within WinCC OA updated randomly, approx. once per 5 seconds.

5/opcua, OpcUaCComm in Function read, Can not read from node group @ opc.tcp://172.16.1.22:4840 (Statuscode: BadTooManyOperations)
17/opcua, OpcUaCServerQueue in Function push, Queue overflow @ OPCUA-Queue, 1000 exceeded, values will be discarded

I have tried upping the "maxRequestQueueSize" config to numbers much greater than 1000 but this did not change the result.

Any help on the matter would be greatly appreciated. Thank you.

[Gertjan van Schijndel]

It seems your OPC UA server is not able to handle this many operations. Resulting in invalid values for the whole group, besides the already queued values, causing the overflow.
Are you using polling or subscriptions?
Which OPC UA server are you using? On the S7-1516 self, Simatic NET or WinCC?

You could try to increase the 'maxRequestQueueSize' config entry.
In case you are using subscriptions you could also try to increase the queue size there.