For more than 8 month I've had an issue with a specific SCADA system acting as OPC UA client to various codesys runtime targets (Raspberry, PFC200, WinV3) and versions (3.5.13.x - 220.127.116.11) Every time the SCADA system lack on performance when the amount of requested points become more than approx. 50. SCADA UPC UA Client reports that OPC UA server returns "BadTooManyOperations". Quality is "Good" but point is "not readable" and "not writable".
So far I have blaimed the SCADA system for this because when i use UA expert as OPC UA client there is no problem in reading 300+ simultainious values from the runtime OPC UA server. Not a single warning or error in the UA Expert log!!
Also if I split the points (60) over more SCADA pictures (2) there is no problem reading the 30+30 = 60 points simultainiously from the target OPC UA server. But if all 60 point go on the same SCADA picture the problem is there.
The support team of the SCADA system has unfortunately been very slow in investigating this problem. And now 8 months later they have come back saying this is "bad performance of the Codesys OPC UA server" and not their SCADA system that is the problem. They have the following statements that I would like someone to either confirm or reject:
1. Codesys OPC UA server has a limit of 100 operations for each service(session?)
2. Codesys OPC UA server is not certified (by OPC foundation?)
I am quite eager to find out who is not performing here !!
it is correct that our OPC UA server has an operation limit of 100 operations per service. This limit does not affect the number of monitored items available as you have also seen with UaExpert.
It is also correct that our OPC UA server is not certified by the OPC Foundation.
But we do checks against the OPC Foundation specification using the official UA Compliance Test Tool.
Additionally we visit the OPC UA interoperability workshops to ensure that our OPC UA Server is compatible to different clients.
The last years we didn’t see any major problems with different clients.
To investigate this problem we need at least a wireshark trace that shows the complete problem. Additional some details of the used client would be helpful.
Please send this together with an bug report on CODESYS Store-> my question "bug support"
Thank you for your reply to this topic.
I will forward the information to the SCADA vendor and hopefully they are willing to set up test system and do wireshark investigations.
The SCADA system used as client is Iconics Genesis64. Have you got any experience using this system as OPC UA client to runtime OPC UA Server?
Could you in more details describe what the UaExpert does to read more that 100 items. It must do something different from what the SCADA system does?
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