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Connections lost with Subscriptions

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15 Feb 2018 17:41 #6052 by support
Hello,

thank you for the new information.

To be fully clear, I believe that the problem firmware 2.5 was supposed to address was not the fact of loss of connection during program update *as such*. The problem was that the communication did not recover afterwards. It is not clear from what you wrote whether it recovers or not.

Status code GoodOverload means (according to OPC UA spec) "Sampling has slowed down due to resource limitations.". We (on the client side) have little to do with it - we are just passing this status code from the server to you. It is possible, for example, that the server cannot sample so many values that fast as you have specified, so the resolution might be to slow down the sampling rate. But, for the precise information, it should be the OPC server vendor who clarifies the GoodOverload status.

Best regards

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15 Feb 2018 15:56 #6051 by Wagner
An update regarding this issue.

Since the PLC was updated to firmware 2.5 the spontaneous connection losses are obviously gone. But if the PLC program is updated we still observe a loss of the connection. This issue seems not to be resolved with firmware 2.5.

Something has changed regarding subscriptions with firmware 2.5.

We have a subscription of ~280 values. The subscriptions are implemented with a SubscribeMultipleMonitoredItems call.

With firmware 2.1 we got as the result one initial value for each subscribed value. With FW 2.5 we get also this initial values but they are repeated two or three times. The first time we receive them with the quality indicator 'Good', the next time they have a quality indicator 'GoodOverload'.

Do you have any clue about this change? Do we have to worry about the indicator 'GoodOverload'?


Kind regards,

Robert

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06 Feb 2018 07:15 - 15 Feb 2018 16:32 #5965 by support
I need the Wireshark log together with other information (time-stamped logs from QuickOPC). I refer you again to this article: kb.opclabs.com/Collecting_information_for_troubleshooting .


Regarding the Siemens OPC UA, we have roughly following information from our partner:
- Firmware 2.1 will lose OPC UA communication after program download and will not go back until the PLC is restarted. Not sure if other operations to the PLC can cause the same.
- The above issue should be resolved in firmware 2.5. But there is a strong evidence suggesting that 2.5 has a memory leak and starts having problems after running for long time.

Best regards
Last edit: 15 Feb 2018 16:32 by support.

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05 Feb 2018 12:17 #5949 by Wagner
Hello,

I know / learned that the connection to the OPC UA server is broken when the PLC program is being updated. This was not the case.

The connection loss we observe normally is spontaneous without any action on our side.

Recently we could reproduce the connection loss while reading data from the S7 OPC UA server with another program on the same machine while our main program was running.

Both programs were using QuickOPC 2017.2.

I wonder if the connection is lost if the OPC UA server or the S7 PLC is very busy. But this is only an assumption.



Best regards

Robert

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05 Feb 2018 11:42 #5948 by support
Thank you.

Additional questions: Haven't you/somebody been uploading programs to the PLC or doing similar PLC configuration changes while this occurred?

Best regards

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05 Feb 2018 11:18 #5947 by Wagner
Hello,

I 7-zipped the WireShark log and attached it to this message.

The model No. of the S7 is 1516 F-3 and the firmware version is 2.1.


Kind regards

Robert

File Attachment:

File Name: WiresharkO...02-05.7z
File Size:326 KB
Attachments:

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05 Feb 2018 11:18 #5946 by Wagner
Hello,

I 7-zipped the WireShark log and attached it to this message.

The model No. of the S7 is 1516 F-3 and the firmware version is 2.1.


Kind regards

Robert

File Attachment:

File Name: WiresharkOPCUA.7z
File Size:326 KB
Attachments:

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05 Feb 2018 10:55 #5945 by support
Hello,

unfortunately there is no file attached to the forum post. This can be by mistake, or because the file had an extension not enabled for upload, or because it was too big. I have now enabled all usual WireShark extension for upload.

Can you please upload again (zip it if it's big). If that fails, I will then provide an alternative means of delivering the file.

In addition, I know you have S7 PLC, but please specify the full model, and also the firmware version. We have indications from our partner of confirmed OPC UA communication issues in several of the Siemens PLC models.

Best regards

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04 Feb 2018 18:20 #5944 by Wagner
Dear Support,

in the meantime I was able to record a WireShark log. Our application should be listed as OPCUAWHM in the logs.

Can you explain why the application looses the connection to the OPC UA server when you look at the WireShark capture?

Please let me know, if you need any further information.


Kind regards,

Robert

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16 Jan 2018 07:08 #5872 by support
Dear Sir,

unfortunately, form the logs you have sent, on our side it looks like that it was either the server or the network that caused the issue.

In order to be able to tell more, would you be willing to make a Wireshark capture of the network traffic between the client and the server? More information: kb.opclabs.com/Collecting_information_for_troubleshooting .

Best regards

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