Log In
Register
Forum
Topic RSS
10:35, EEST
August 20, 2014
Offline
Hi,
is it possible in OPC UA to read an array of size 1? We had the problem that a Siemens PLC was upgraded with the Simatic Server to OPC UA. Inside the PLC programm it is possible (and sometimes necessary) to create arrays of size 1. Those arrays were no longer arrays in OPC UA and the Java SDK didn’t recognize them as arrays, but as primitive variables.
Question: Is it even possible to read an arrays of size 1?
Thanks
Ibrahim
12:45, EEST
April 17, 2013
Offline
Hello,
Yes, it’s possible to have arrays of size 1 in OPC UA.
In OPC UA, array data types are defined by DataType, ValueRank and ArrayDimensions attributes. As a first step, you should see what values these attributes contain.
15:03, EEST
August 20, 2014
Offline
Hi,
thanks for the quick answer.
I checked the mentioned variable again and its attributes. This are the values:
DataType: Int32
ValueRank: 1
ArrayDimensions: UInt32 Array[1] –> [0] 1
But the strange thing is, that if i call “…isArray()” on this NodeId, i get false… What could be the reason for this? I also tried to write a primitive int value into this NodeId and it worked fine.
Thanks
Ibrahim
16:07, EEST
April 17, 2013
Offline
Hello,
Thank you for the reply. The node attributes have sensible values.
It seems like the server responds with scalar values even though array values should be used. This seems like a purely server side issue, the client SDK should not modify the received values in any way. Also, writing scalar value to this node should fail because the supplied value is not of the same type as the attribute’s value. This check should be done in the server application. You should inform the server vendor about these issues.
Please let us know if you have further comments or questions about this.
1 Guest(s)
