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OPC-UA client session is disconnecting, why?

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13 Jun 2016 09:06 #4122 by openventure
Hello, I want inform you that we still have the problem, i.e. in around one time by week we have a stop. the service appear blocked and there is not interaction with opc server.
From the last version installed 5.35 build 1126.1 we have an error on the windows system event, do you know what it's mean?

Internal error (only first occurrence is logged): 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.

p.s. yesterday we have installed a new release, the build 1173 as you have suggested some days ago.

My greetings,

paolo.

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12 May 2016 09:09 #4037 by support
I have investigated this and, somewhat contrary to what the error text says, determined to be harmless (in this particular instance - it depends on the precise error details)- it is basically a "false positive", a log entry that we should not be making in the first place. We will fix that in a future version.

If that is the only problem remaining, you should ignore it, and it will be safe to do so.

Best regards
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12 May 2016 08:39 #4036 by openventure
Do you have some news about the error:

OPCLabs-UAEngine message:INTERNAL ERROR. The OPC-UA engine might be in an unstable state.

That happens from 3 to 8 time by day.

thanks in advance,
p

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06 May 2016 07:30 #4027 by support
Build 5.35.1173.1 resolves an issue which sometimes caused a deadlock inside QuickOPC resulting in (among others) ability to automatically reconnect. It can be part of your problem, I am not sure, but it's not a blind shot, it is certainly worth trying.

I strongly recommend using it, because there is a possible relation to your issue, and it won't make any sense to try analyzing a problem with software that is not up-to-date.

If the server is local, yes we can rule out network comm problems. But a server-side problem can still be present.

Best regards
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05 May 2016 16:40 #4026 by openventure
Hello Dear supporter,

I don't mind you forgot me, but I hope you don't leave me alone again:)

I would tend to exclude communication problem because server (kepware) and client are on the same machine.

Excuse me, I don't understand which is the problem that the new version, should solve?

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05 May 2016 14:31 #4025 by support
Dear Sir,

first of all, I apologize for not replying to your post from April 24. We reply to all posts, but somehow this one got lost.

There are two issues in here: First is, why the problem does appear. This may, or may not be a correct behavior on the client side - it can (and likely, is) a genuine communication problem (or server-side problem( that the client cannot influence. And the second issue is, why the client doe not recover by itself.

As to the second problem, we have just recently fixed a bug that could be causing it - it was very similar. It is unlikely that you are using the build with the fix: It is 5.35.1173.1 (or higher), and it has been released around April 21. I strongly suggest that you download the latest build, rebuild your project with it, and retest.

As to why the communication problem appears in the first place: It is about a keep-alive mechanism, which requires the server to respond periodically, even if there is no data. It would be necessary to analyze on the protocol level (using e.g. Wireshark) to figure out precisely whether the server indeed has stopped publishing, or whether it is the client misunderstanding something.

The "Internal error": We will have a look at it, it should not be showing up. but as you said, it appears to be benign and is probably just a "false positive" kind of message.

Best regards

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04 May 2016 16:55 - 04 May 2016 17:07 #4024 by openventure
IT's passed a week and we have again the problem.
These are, the lines of messages, after these, nothing works anymore, we must kill the service (because it doesn't stop normally in this case) and start it.

OPCLabs-UAEngine message:The OPC-UA client session with connect sequence number 1 is disconnecting from endpoint URL "opc.tcp://10.74.137.71:49320".

OPCLabs-UAEngine message:The OPC-UA client session with connect sequence number 1 has disconnected from endpoint URL "opc.tcp://10.74.137.71:49320".

OPCLabs-UAEngine message:The OPC-UA client session on endpoint URL "opc.tcp://10.74.137.71:49320" failed at tick 794052483 and will retry in 10000 milliseconds.


The good news is that, during the day, we have some errors from OPC engine, even if they not cause stop of functionalities.

OPCLabs-UAEngine message: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.


What these errors mean for you?
Attachments:
Last edit: 04 May 2016 17:07 by openventure.

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24 Apr 2016 11:24 - 26 Apr 2016 14:51 #4015 by openventure
Thank a lot,
We choose to keep library 5.35 in the applicazioni and seems ok.

But after awhile I gave a message: 4/24/2016 1:41:54 PM: OPC Event 0: OPCLabs-UAEngine message:The OPC-UA subscription ID 11 publishing has stopped on the client session with connect sequence number 1 to endpoint URL "opc.tcp://10.74.137.71:49320" for approximate current duration of 10716.0715 milliseconds. The current keep-alive count is 10 and the current publishing interval is 500 milliseconds. Further such errors on this session will not be logged.
4/24/2016 1:49:19 PM: OPC Event 0: OPCLabs-UAEngine message:The publish status changed queue for OPC-UA subscription ID 11 on the client session with connect sequence number 1 to endpoint URL "opc.tcp://10.74.137.71:49320" has overflown its limit of 100 entries. Further such warning on this session will not be logged.

The code that cause the message is:
myLogger.Log(string.Format("OPC Event {0}: {1} message:{2}",eArgs.Category, eArgs.Source, eArgs.Message));

After that message the service lost every subscriprions and I have to restart it, to restore functionality. :(

What can I do to have more info on error?

By the way, when the message above happened, only the lifebit function is in run and neither other request are made on the opc server. Pratically nobody works on the plant.
Thank in advances,
My greetings,
P
Last edit: 26 Apr 2016 14:51 by openventure.

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24 Apr 2016 07:00 #4014 by support
Regarding Windows Server 2008, our official requirements for QuickOPC version 5.35 (the crrent version) are Microsoft Windows Server 2008 R2 (x64) with Service Pack 1, and .NET Framework 4.5, 4.5.1, 4.5.2, or 4.6.

The edition of the server (Standard, ...) does not matter. You should be able to use QuickOPC version 5.35 as long as you have the "R2" operating system with SP1.

If you do not have that or cannot have that, it might still be possible to use QuickOPC 5.35, although it is not officially supported. The setup program will most likely refuse to install on such a system, but if you build your project elsewhere, the compiled application is likely to run well.

The last QuickOPC version to officially support Windows Server 2008 without R2+SP1 was 5.31. That is not going to get you far. I will send you a download link to it by email.

Best regards
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23 Apr 2016 23:26 #4013 by openventure
Thanks for your suggesting, but on my server I have windows server 2008 standard edition, can I have a version compatible with it?

Please, help me, I don't have the chance to change the operative system, and I can't find this anywhere on your website.


thanks in advance,

Best greetings,

p

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