Dear Sir,

this particular log entry is caused by an internal error in QuickOPC. We already know about it and have investigated it. You can call it a bug, but we have looked at it very closely and determined that it is harmless. It will be fixed in the upcoming QuickOPC version, but you can really safely ignore it.

Best regards

Dear sir,

Last week we ran another OPC test and send the results to Bosch Rexroth. Our current OPCLabs version: 5.35.442.1

While analyzing, we at DG press and Bosch Rexroth were wondering what the following log entry in our logging means:

2016-06-01 16:01:00,849 [18] ERROR EasyUAClient: OPCLabs-UAEngine, INTERNAL ERROR. The OPC-UA engine might be in an unstable state.
An exception of type 'System.NullReferenceException' from source 'OpcLabs.EasyOpcUAInternal' has occurred in OPC-UA SDK callback 'Subscription.PublishStatusChanged'. The exception descend follows.(1) {System.NullReferenceException} OpcLabs.EasyOpcUAInternal(ConsumeSdkPublishStatusChangedQueue) -> Object reference not set to an instance of an object.

The first part: “2016-06-01 16:01:00,849 [18] ERROR EasyUAClient:” is from our logging. The rest is the OpcLabs.BaseLib.Diagnostics.LogEntryEventArgs.Message and OpcLabs.BaseLib.Diagnostics.LogEntryEventArgs.Source from the OpcLabs.EasyOpc.UA.EasyUAClient.LogEntry event.

We noticed that we get this error whenever we lose connection. Is this correct?

Are there other cases this error can appear?

Does this only appear from a lost hardware connection or can it also be from a software problem?

We look forward to your response.

Dear Sir,

this is most likely a server problem, i.e. the server not responding fast enough. The client detects the situation, and consequently deletes the subscription (and then attempts to re-create it later).

The newer QuickOPC versions (currently 5.35.442.1, from www.opclabs.com/products/quickopc/downloads ) include better diagnostics for this case. Specifically, the error/log messages contain additional information which allows to easier pinpoint the problem.

Please re-build your project with version 5.35 and run the tests again. The error messages should then contain more information. Only then it would make sense to look at the Wireshark (if at all).

Best regards

We have the same problem again an OPC-UA subscription publishing has stopped. Can you give me a tips or solation for this problem? In the attachment, I have put three log files (WireShark, HMI.txt and HMI-OPCTrace.log) with a logging of the subscription publishing has stopped. In the Wireshark logging, we find-out that the HMI with source IP 172.17.61.41 sent to destination IP 172.17.1.3 or IP 172.17.1.3 DeleteSubscriptionReqeust in the next line you can see that the server sent a DeleteSubscriptionResponse. Via the HMI (EasyUAClient) we don’t unsubscribe or delete the relation why a DeleteSubscriptionReqeust?

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WireShark log file:
In line 5758, the EasyUAClient has sent DeleteSubscriptionRequest why this request ?

No exceptions in log file HMI.txt:
Normally we get an exception from EasyUAClient, but there was no exception sent? In the Wireshark log file at line 5758, EasyUAClient has sent DeleteSubscriptionRequest, why this request? The UA server from Bosch Rexroth sent correct the response DeleteSubscribeResponse.
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WireShark log file:
In line 213999, the EasyUAClient has sent DeleteSubscriptionRequest why this question? In the log file, HMI.txt the exception is received (look at line 1229).

Exceptions in log file HMI.txt file:
We get an exception from EasyUAClient at line 1230 until 1272.
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WireShark log file:
In lien 387977, the EasyUAClient has sent DeleteSubscriptionRequest why this request? In the log file, HMI.txt the exception is received (look at line 5730).

Exceptions in log file HMI.txt file:
We get an exception from EasyUAClient at line 5729 until 5887.
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Please let us know your feedback in any case, on this problem or on how you can help use to solve this problem.

We had attachment problems standard files are to big (look Snapshot Wireshark)