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  9. Read array of byte return null

Read array of byte return null

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13 Jun 2018 11:54 #6442 by mpp
Replied by mpp on topic Read array of byte return null
We're using a Schneider Electric PLC and it has OPC-UA capabilities.
We are definitely not configuring it correctly.

Many thanks for your help

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13 Jun 2018 10:16 #6439 by support
Replied by support on topic Read array of byte return null
This has to be resolved on the server side. You cannot "convert" the folder to a byte array. Either the server actually provides a different variable somewhere else where the array is actually readable, or the server needs to be configured differently, or perhaps it does not have that capability through OPC UA at all - all of this can only be answered by the server vendor.

Best regards

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13 Jun 2018 07:56 - 13 Jun 2018 07:56 #6438 by mpp
Replied by mpp on topic Read array of byte return null
Hi,

I downloaded UAExpert and the result is the same.

If I read the full array it shows Null in the DataType column and an empty cell in the Value one.
If I read a single value of the array it shows Byte in the DataType column and its current value.

I can also see that the array has properties:
  • NodeClass = Object
  • HasTypeDefinition = FolderType
Is it correct?

How can I convert "Folders" in byte arrays?
Is it something I can do from c# or it is something that I have to fix on the UA Server?

Thanks again,
Last edit: 13 Jun 2018 07:56 by mpp.

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12 Jun 2018 15:24 #6434 by support
Replied by support on topic Read array of byte return null
Hello,

this looks more like a server issue. Have you tried reading the array with some other OPC *UA* client, and what were the results?

Thank you

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12 Jun 2018 15:01 - 12 Jun 2018 15:11 #6433 by mpp
Read array of byte return null was created by mpp
Hi,

I am using the OPC UA lib (5.35).
I'm new to OPC UA, maybe I missed something in the documentation.

I want to read a byte array but the return value is null (also the return type):
var a = easyUAClient.Read(serverDescriptor, "nsu=OpcUaServer;ns=2;s=Application.array_bytes");
//returns {(null) {} @6/12/2018 5:02:27 PM @@6/12/2018 5:02:27 PM; Good}

I am able to access the single array values:
var b = easyUAClient.Read(serverDescriptor, "nsu=OpcUaServer;ns=2;s=Application.array_bytes[1]");
//returns {234 {System.Byte} @6/12/2018 5:01:22 PM @@6/12/2018 5:01:22 PM; Good}

And if I try to get the
UAAttributeId.ArrayDimensions
value I get 10 which is correct.

If I read the full array with OPC Classic I do not have any problem.

Am I doing something wrong?


Thanks
Last edit: 12 Jun 2018 15:11 by mpp.

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