How read and write array of struture?

[sergeishugaev]

Hello!
I need an OPC UI client to read and write arrays of structures, there can also be arrays of variables inside structures. An example of the structure from Codesys 3.5 is shown in the figure.

Structure:

Substructure:

Array of structure:

I can see this array through UA expert, but I don't understand how I can get this data using your library. Individually, I can read or write any variable in the array, but this is inconvenient, since there is quite a lot of data.

Tell me how to work with such arrays, how to read and write variables located in arrays of structures?

[kevinherron]

Can you also provide some screenshots of what these nodes look like in UaExpert? Have you written any code yet?

[sergeishugaev]

Codesys not supported the OPC UA 1.03 datatype dictionary mechanism.
And I couldn't read the structure to ExtensionObject. I got an exception.

[kevinherron]

Codesys not supported the OPC UA 1.03 datatype dictionary mechanism.

Hmm, I wonder if that has changed. I am pretty sure they supported it at one point. Support for the OPC UA 1.04+ DataTypeDefinition attribute has already been implemented in the dev/1.0 branch but that isn't much help right now.

If you can somehow make this server publicly accessible I can poke around at it.

[sergeishugaev]

My plc is the opc ui server. I programmed the plc via the codesys ide. The plc program runs on codesys runtime management. I asked question about "supported 1.03 datatypes" the support of the plc manufacturer . They told me that it was not supported. To be honest, I don't know the opc ui standard very well. Therefore, I have difficulties in implementation. I can provide you with an extended access to the plc via the opc ui, but I will be able to do this only next week.

[sergeishugaev]

I have given public access to my test PLC (Codesys 3.5).
Could you try to connect to PLC via OPC US and try to read/write the array of structures (|var|SPK107 (M01).Application.GVL.astShipmentAuto)?

opc.tcp://85.26.128.105:4840

[sergeishugaev]

[kevinherron]

I'm able to read the array by modifying UnifiedAutomationReadWriteCustomExample.java as I suggested earlier:

        client.addSessionInitializer(new BinaryDataTypeDictionarySessionInitializer(StructCodec::new));

        client.connect();

        var nodeId = NodeId.parse("ns=4;s=|var|SPK107 (M01).Application.GVL.astShipmentAuto");
        DataValue value = client.readValues(0.0, TimestampsToReturn.Both, List.of(nodeId)).get(0);

        ExtensionObject[] xos = (ExtensionObject[]) value.getValue().getValue();

        logger.info("astShipmentAuto:");
        for (int i = 0; i < xos.length; i++) {
            ExtensionObject xo = xos[i];
            Object obj = xo.decode(client.getDynamicEncodingContext());
            logger.info("  astShipmentAuto[{}]: {}", i, obj);
        }

Result:

07:17:44.574 [main] INFO  o.e.m.e.c.UnifiedAutomationReadCustomDataTypeExample - astShipmentAuto:
07:17:44.622 [main] INFO  o.e.m.e.c.UnifiedAutomationReadCustomDataTypeExample -   astShipmentAuto[0]: Struct{name=Application.SHIPMENT_AUTO, members={diSiloStartWeight=Member{name=diSiloStartWeight, value=0}, dwComponentID=Member{name=dwComponentID, value=0}, wsComponentName=Member{name=wsComponentName, value=}, xInProgress=Member{name=xInProgress, value=false}, xWriteFile=Member{name=xWriteFile, value=false}, wsPreparationName=Member{name=wsPreparationName, value=}, bySiloNum=Member{name=bySiloNum, value=0}, byShipmentError=Member{name=byShipmentError, value=0}, wsShipmentStartTime=Member{name=wsShipmentStartTime, value=}, dwShipmentTag=Member{name=dwShipmentTag, value=0}, dwPreparationID=Member{name=dwPreparationID, value=0}, wsShipmentStopTime=Member{name=wsShipmentStopTime, value=}, wsShipmentName1=Member{name=wsShipmentName1, value=}, wsShipmentName2=Member{name=wsShipmentName2, value=}, wsComponentPrice=Member{name=wsComponentPrice, value=}, wsComponentDryRatio=Member{name=wsComponentDryRatio, value=}, dwShipmentID=Member{name=dwShipmentID, value=0}, byOutputNum=Member{name=byOutputNum, value=0}, diComponentWeight=Member{name=diComponentWeight, value=0}, astSilo=Member{name=astSilo, value=[Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}]}, diSiloStopWeight=Member{name=diSiloStopWeight, value=0}}}
07:17:44.627 [main] INFO  o.e.m.e.c.UnifiedAutomationReadCustomDataTypeExample -   astShipmentAuto[1]: Struct{name=Application.SHIPMENT_AUTO, members={diSiloStartWeight=Member{name=diSiloStartWeight, value=0}, dwComponentID=Member{name=dwComponentID, value=0}, wsComponentName=Member{name=wsComponentName, value=}, xInProgress=Member{name=xInProgress, value=false}, xWriteFile=Member{name=xWriteFile, value=false}, wsPreparationName=Member{name=wsPreparationName, value=}, bySiloNum=Member{name=bySiloNum, value=0}, byShipmentError=Member{name=byShipmentError, value=0}, wsShipmentStartTime=Member{name=wsShipmentStartTime, value=}, dwShipmentTag=Member{name=dwShipmentTag, value=0}, dwPreparationID=Member{name=dwPreparationID, value=0}, wsShipmentStopTime=Member{name=wsShipmentStopTime, value=}, wsShipmentName1=Member{name=wsShipmentName1, value=}, wsShipmentName2=Member{name=wsShipmentName2, value=}, wsComponentPrice=Member{name=wsComponentPrice, value=}, wsComponentDryRatio=Member{name=wsComponentDryRatio, value=}, dwShipmentID=Member{name=dwShipmentID, value=0}, byOutputNum=Member{name=byOutputNum, value=0}, diComponentWeight=Member{name=diComponentWeight, value=0}, astSilo=Member{name=astSilo, value=[Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}]}, diSiloStopWeight=Member{name=diSiloStopWeight, value=0}}}
07:17:44.629 [main] INFO  o.e.m.e.c.UnifiedAutomationReadCustomDataTypeExample -   astShipmentAuto[2]: Struct{name=Application.SHIPMENT_AUTO, members={diSiloStartWeight=Member{name=diSiloStartWeight, value=0}, dwComponentID=Member{name=dwComponentID, value=0}, wsComponentName=Member{name=wsComponentName, value=}, xInProgress=Member{name=xInProgress, value=false}, xWriteFile=Member{name=xWriteFile, value=false}, wsPreparationName=Member{name=wsPreparationName, value=}, bySiloNum=Member{name=bySiloNum, value=0}, byShipmentError=Member{name=byShipmentError, value=0}, wsShipmentStartTime=Member{name=wsShipmentStartTime, value=}, dwShipmentTag=Member{name=dwShipmentTag, value=0}, dwPreparationID=Member{name=dwPreparationID, value=0}, wsShipmentStopTime=Member{name=wsShipmentStopTime, value=}, wsShipmentName1=Member{name=wsShipmentName1, value=}, wsShipmentName2=Member{name=wsShipmentName2, value=}, wsComponentPrice=Member{name=wsComponentPrice, value=}, wsComponentDryRatio=Member{name=wsComponentDryRatio, value=}, dwShipmentID=Member{name=dwShipmentID, value=0}, byOutputNum=Member{name=byOutputNum, value=0}, diComponentWeight=Member{name=diComponentWeight, value=0}, astSilo=Member{name=astSilo, value=[Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}, Struct{name=Application.SILO, members={axOutput=Member{name=axOutput, value=[false, false]}, xEnabled=Member{name=xEnabled, value=false}}}]}, diSiloStopWeight=Member{name=diSiloStopWeight, value=0}}}

... snipped ...

It seems this server does indeed support the legacy DataType dictionary mechanism.

[kevinherron]

Oops, that was written against the dev/1.0 branch.

Here it is for 0.6.x:

        client.addSessionInitializer(new DataTypeDictionarySessionInitializer(new GenericBsdParser()));

        client.connect().get();

        NodeId nodeId = NodeId.parse("ns=4;s=|var|SPK107 (M01).Application.GVL.astShipmentAuto");
        DataValue value = client.readValue(0.0, TimestampsToReturn.Both, nodeId).get();

        ExtensionObject[] xos = (ExtensionObject[]) value.getValue().getValue();

        logger.info("astShipmentAuto:");
        for (int i = 0; i < xos.length; i++) {
            ExtensionObject xo = xos[i];
            Object obj = xo.decode(client.getDynamicSerializationContext());
            logger.info("  astShipmentAuto[{}]: {}", i, obj);
        }

[sergeishugaev]

Thanks a lot!

[akeklak]

Hi all, I am curious about writing updated values back to such a node. I have been working off of the UnifiedAutomationReadCustomDataTypeExample, and am able to successfully read and decode into Structs (Object). Similarly, I can wrap that same Struct back into a Variant/DataValue and write it back to the node using the encoding ID from the original xo (at least, I don't get an error), but I'm not able to figure out how to modify the Struct (as is done in the other ReadWrite example, where the CustomDataType java class is pre-defined).

Using jackson, I am able to turn the decoded Struct into a json string, which I can then modify trivially. I feel it should be possible to reconstitute the struct from the modified json, and then write it back to the server, without having to manually specify any encoding/decoding. But so far I haven't had any luck with that. Appreciate any help!

[kevinherron]

The Struct class returned by the default codecs is... not very useful, especially if you need to write. It's fully immutable so you have to construct new instances of it that contain the changes you want.

I don't use this implementation in practice. When constructing the DataTypeDictionarySessionInitializer I pass an instance of JsonBsdParser instead, which will produce a GSON JsonObject instead. Easier to work with....

This situation is greatly improved for 1.0. There's a new DynamicStruct that should actually be a usable to JSON. See https://github.com/eclipse/milo/blob/dev/1.0/milo-examples/client-examples/src/main/java/org/eclipse/milo/examples/client/UnifiedAutomationReadCustomDataTypeExample2.java for a preview.

[akeklak]

@kevinherron Awesome - Using the JsonBsdParser gets me exactly what I need - can modify the json and then write it back to the server. (all still in 0.6.12) Thank you for your help and look forward to the DynamicStructs!