question opc ua

2020-02-27T14:40:59.853000Z

Hi,
I need to Read/Write variables from Codesys to runing python script. I tested example OPCUA where is changing iConunter variable in Codesys project and the value of iCounter is printed by means of OPC UA client "simpleclientRaspi.py". It works well. But I don't need print it I need to use this value in my python script. How can I extract value of iCounter variable?

Peter

question opc ua

2020-02-27T14:40:59.325000Z

Hi,

the NodeIDs on OPC UA could have differnet format:

Numeric, String, Guid, Opaque

the NodeID is the following:

typedef struct _OpcUa_NodeId
{
OpcUa_UInt16 IdentifierType;
OpcUa_UInt16 NamespaceIndex;

union
{
    OpcUa_UInt32     Numeric;
    OpcUa_String     String;
    OpcUa_Guid*      Guid;
    OpcUa_ByteString ByteString;
}
Identifier;

}
OpcUa_NodeId;

The ID is assigned by the server. Therefore, different IDs are mixed in the server.

Best Regards
Edwin

question opc ua

2020-02-27T14:40:58.830000Z

hello:

After investigating, testing and spending some neurons.

I have managed to get one of the scadas even if it does not work to discover I can register the points with their full name (thanks a lot for the example edwin helped me a lot).

a question, there are tags that are defined by string and others that are seen by a number, all have that string and that number or depends on how the server is used or one system or the other?

question opc ua

2020-02-27T14:40:57.383000Z

the scadas are a niagara and another b-scada, niagara needs a license but b-scada is free you can download and try without problem.

I'm going to try to see if I guess something with the help of an expert

http://scadauniversity.com/Home/Download

thanks edwin.

question opc ua

2020-02-27T14:40:56.849000Z

Hi,

'two different scadas' - we try ro reproduce it if you send us links or more information to these products.
If you compare the NodeId between, OPCUA Expert and the non working scada, you could maybe get an idea
how to access.... ( I mean with the help of OPCUA expert)
Maybe this trick here helps to get the correct

https://www.codesys-blog.com/kommunikat ... verbinden/

Zitat:
I have to say that it is anything but trivial how the NodeID is composed. But I found a great trick that saves a lot of time. What annoyed me is the fact that I could not copy the NodeID anywhere. In my tests, I had countless script errors that only arose because I had transmission errors copying out the NodeID (for example, NS4 | String || var | CODESYS Control Win V3 x64.Application.GVL.uiCycleCounter

BR
Edwin

question opc ua

2020-02-27T14:40:56.330000Z

hello:

I have tried the opc ua server of codesys with runtime raspberry with uaexpert and it works without problem

But I tested it with two different scadas and both give me an error in the nodeid (CODESYS control for raspberry pi SL) both return BadNodeIdUnknown, there is some configuration to change this nodeID.

It is rare that two client opc ua return the same error.

With a client opc ua test, they work perfectly, and observed that these clients generate an XML schema that codesys does not generate, is there a possibility of this?

thanks

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