> For the complete documentation index, see [llms.txt](https://docs.cybus.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cybus.io/1-7-3/documentation/industry-protocol-details/opc-ua/opc-ua-object-types.md).

# OPC UA Object Types

OPC UA object types define class like structures in OPC UA namespace that can be instantiated and added to the server address space.

{% hint style="info" %}
For more information on UPC UA Object Types, see the [OPC Foundation Reference](https://reference.opcfoundation.org/v104/Core/docs/Part3/5.5.2/).
{% endhint %}

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

## Example Commissioning File

Download:

{% file src="/files/R9SaHQD7HG6N7kDWOFik" %}

{% code lineNumbers="true" %}

```yaml
---
description: demo for OPC UA objecttype nodes

metadata:
    name: OPC UA Objecttypes demo

resources:
    opcuaServer:
        type: Cybus::Server::Opcua
        properties:
            hostname: 192.168.178.46
            securityModes: ['None', 'SignAndEncrypt']
            nodesetFiles: ['di', 'machinery', 'ia', '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/'
```

{% endcode %}

## Output Format

The server provides the structure of the object types and its values as a JSON structure as the example:

{% code lineNumbers="true" %}

```yaml
{
    'ObjectTypeSample':
        {
            '_children':
                {
                    'OperationMode':
                        {
                            '_children':
                                {
                                    'ChildExample':
                                        {
                                            '_children': {},
                                            '_metadata': { 'nodeClass': 'Variable', 'dataType': 'Int64' },
                                            '_value': '1883344340925958233434349340394',
                                        },
                                },
                        },
                    '_metadata': { 'nodeClass': 'Variable', 'dataType': 'Int32' },
                    '_value': 0,
                },
        },
    '_metadata': { 'nodeClass': 'Object' },
}
```

{% endcode %}

| \_metadata | contains all metadata on a 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    | contains 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:

{% code lineNumbers="true" %}

```yaml
{ 'ObjectTypeSample': { '_children': { 'OperationMode': { '_children': { 'ChildExample': { '_value': '50000000000000' } }, '_value': 10 } } } }
```

{% endcode %}


---

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