OPC UA (Object Types)

OPC UA object types define class like structures in OPC UA namespace that can be instanciated and added to the server address space. For more details on OPC UA Object Types please refer to: <https://reference.opcfoundation.org/v104/Core/docs/Part3/5.5.2/>

It is possible to create a instance of an objecttype by using the resource type Cybus::Node::OpcuaObject

Example Commissioning File

Download: opcua-objecttype-example.yml

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---
  description: demo for OPC UA objecttype nodes
  
  metadata:
    name: OPC UA Objecttypes demo

  resources:
    opcuaServer:
      type: Cybus::Server::Opcua
      properties:
        alternateHostname: 192.168.178.46
        securityModes: ['None', 'SignAndEncrypt']
        nodesetFiles: ['di', 'machinery', 'machineTool']
        securityPolicies: ['None', 'Basic256Sha256']
        allowAnonymous: true
        port: 4841

    parentNodeRoot:
      type: Cybus::Node::Opcua
      properties:
        parent: !ref opcuaServer
        browseName: cybus
        nodeId: ns=1;s=cybus
        nodeType: Object

    #######################################################
    #
    # Sample of an insance of an 
    # machine tool type. The type "MachineToolType" is 
    # defined in the MachineTool Umati namespace
    #
    #######################################################
    testMachineToolType:
      type: Cybus::Node::OpcuaObject
      properties:
        parent: !ref parentNodeRoot
        browseName: MyMachineToolTypeTest
        objectTypeName: MachineToolType
        sourceNamespaceUrl: 'http://opcfoundation.org/UA/MachineTool/'

Output Format

The server provides the structure of the objecttyes and it’s values as a json structure as the example:

{
  "ObjectTypeSample": {
    "_children": {
      "OperationMode": {
        "_children": {
          "ChildExample": {
            "_children": {},
            "_metadata": {
              "nodeClass": "Variable",
              "dataType": "Int64"
            },
            "_value": "1883344340925958233434349340394"
          }
        }
      },
      "_metadata": {
        "nodeClass": "Variable",
        "dataType": "Int32"
      },
      "_value": 0
    }
  },
  "_metadata": {
    "nodeClass": "Object"
  }
}
Details

_metadata

contains all metadata on an node. The nodeclass corresponds to the node-opcua Nodeclass enum documented here: <http://node-opcua.github.io/api_doc/2.0.0/enums/nodeclass.html> On nodes of type “Variable” the dataType entry indicates the OPC UA native data type documented here: <http://node-opcua.github.io/api_doc/2.0.0/enums/datatype.html>

_children

contains child objects in the OPC UA object tree

_value

cotains the plain serialized value as JSON

Writing Updates

Writing updates to the opc ua object type can be achieved by publishing to the <ObjectNodeName>/write topic. The same json structure can be used with updated data in the _value items. For data updates on U/INT64 please review the section on BigInt datatypes in OPC UA Server documentation. It is not necessary to update the complete structure. You can also only write a json structure that contains the direct value update. To update all values for the example structure above, only the following structure would be required:

{
  "ObjectTypeSample": {
    "_children": {
      "OperationMode": {
        "_children": {
          "ChildExample": {
            "_value": "50000000000000"
          }
        },
        "_value": 10
      }
    }
  }
}