# OpcInstanceNode Class

<span class="api-meta">abstract</span>

<dl class="api-definition">
<dt>Namespace</dt>
<dd><a href="../namespaces/opc.uafx">Opc.UaFx</a></dd>
<dt>Assembly</dt>
<dd>Opc.UaFx.Advanced.dll</dd>
<dt>Package</dt>
<dd>Opc.UaFx.Advanced v2.59.0</dd>
<dt>Members</dt>
<dd><a href="./members">OpcInstanceNode Members</a></dd>
</dl>

Defines the abstract base class of all instance nodes.

## Syntax

<div class="api-signature" data-lang="csharp">

```csharp
public abstract class OpcInstanceNode : OpcNode
```

</div>

<div class="api-signature" data-lang="vbnet">

```vbnet
Public MustInherit Class OpcInstanceNode
    Inherits OpcNode
```

</div>

## Inheritance

[Object](https://learn.microsoft.com/dotnet/api/system.object) → [OpcNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnode/) → **OpcInstanceNode**

## Implements

<ul class="api-implements">
<li><a href="../opc.uafx.iopcnode/">IOpcNode</a></li>
<li><a href="../opc.uafx.iopcnodeinfo/">IOpcNodeInfo</a></li>
</ul>

## Derived types

- [OpcMethodNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmethodnode/)
- [OpcObjectNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcobjectnode/)
- [OpcVariableNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcvariablenode/)

## Remarks

An instance node is a specialization of the [OpcNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnode/) that references a modelling rule (see [ModellingRuleId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#modellingruleid)) with the [HasModellingRule](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcreferencetype/#hasmodellingrule) reference while it is the target node of a hierarchical reference from a type definition node or another OpcInstanceNode.

## Properties

| Name | Description |
|---|---|
| [DefaultReferenceTypeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#defaultreferencetypeid)<span class="api-meta">protected · virtual</span> | Gets the default identifier which identifies the type that defines the underlying node reference within this OpcInstanceNode is referenced by its parent node. |
| [DefaultTypeDefinitionId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#defaulttypedefinitionid)<span class="api-meta">protected · virtual</span> | Gets the default identifier which identifies the node that defines the underlying node type from that this OpcInstanceNode has been created. |
| [InheritReferenceTypeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#inheritreferencetypeid)<span class="api-meta">protected · virtual · since v2.54</span> | Gets a value indicating whether the [DefaultReferenceTypeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#defaultreferencetypeid) of the current node is to be used for its children nodes initial [ReferenceTypeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#referencetypeid). |
| [ModellingRuleId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#modellingruleid) | Gets or sets the identifier which defines how the OpcInstanceNode is used for instantiation. |
| [Parent](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#parent)<span class="api-meta">override</span> | Gets the parent node of the node. |
| [ReferenceType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#referencetype) | Gets a value which defines a pre-defined used [ReferenceTypeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#referencetypeid) as one of the members defined by the [OpcReferenceType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcreferencetype/) enumeration to simplify querying standard reference types. |
| [ReferenceTypeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#referencetypeid) | Gets or sets the identifier which identifies the node that defines the semantic of the reference between a source and a target node and generally reflects an operation between the two, such as "A contains B". |
| [TypeDefinitionId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#typedefinitionid) | Gets or sets the identifier which identifies the node that defines the underlying node type from that this OpcInstanceNode has been created. |

## Methods

| Name | Description |
|---|---|
| [AddChild](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#addchild) | Adds the `node` specified as a child node of this node. |
| [GetNodeValue](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#getnodevalue)<span class="api-meta">2 overloads · since v2.20</span> | Retrieves the value of the child variable node with the `name` specified in the [Namespace](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnode/members#namespace) of this node. |
| [InitializeDefaults](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#initializedefaults)<span class="api-meta">protected · override</span> | Initializes the default values used by the OpcInstanceNode. |
| [RemoveChild](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#removechild) | Removes the `node` specified from the child nodes of this node. |
| [RemoveNotifier](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#removenotifier)<span class="api-meta">override</span> | Removes the `node` from the collection of notifiers (= event sources) of this node. |
| [SetNodeValue](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcinstancenode/members#setnodevalue)<span class="api-meta">2 overloads · since v2.20</span> | Changes the value of the child variable node with the `name` specified in the [Namespace](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnode/members#namespace) of this node and applies the change. |

Inherits members from [OpcNode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnode/members).

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.5–v2.59 |