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Initializers

The initializers section sets initial values for variable nodes. These values are embedded in the generated NodeSet2.xml and loaded by the OPC UA server on startup.

Initializers can be placed either inside an instance (scoped to that instance) or at the top level of the model (using full paths).

Setting initial values​

Setting initial values
instances:
  - browseName: Sensor1
    typeDefinition: SensorType
    organizedBy: /ua:Objects
    initializers:
      - variable: Temperature
        value: 22.5
      - variable: Pressure
        value: 1013.25

Accessing properties of an AnalogItemType variable​

Use . to reach the properties (e.g. EURange, EngineeringUnits) of a variable node:

AnalogItemType property path
instances:
  - browseName: Sensor2
    typeDefinition: SensorType
    organizedBy: /ua:Objects
    initializers:
      - variable: Level
        value: 75.0
      - variable: Level.ua:EngineeringUnits
        value: "%"

Engineering units shorthand​

For AnalogItemType-based variables, engineeringUnits accepts a plain unit string — no need to write out the full UNECE record:

Engineering units shorthand
instances:
  - browseName: Sensor3
    typeDefinition: SensorType
    organizedBy: /ua:Objects
    initializers:
      - variable: Level
        value: 42.0
        engineeringUnits: "%"
      - variable: Temperature
        value: 23.5
        engineeringUnits: "°C"

Top-level initializers (full path syntax)​

Top-level initializers: uses the full InstanceName/VariableName path. Useful for keeping instance declarations and initial values in clearly separate sections:

Top-level initializers
initializers:
  - variable: Sensor1/Temperature
    value: 18.0
  - variable: Sensor1/Pressure
    value: 1005.0

Duplicate path detection​

The LSP server detects duplicate variable: paths within the same initializers: block and reports a DSL-E error. Each variable path must appear at most once.

📄 Full working example — initializers.model.yaml
# yaml-language-server: $schema=../../../../schemas/nodeset2.schema.json
#
# Living documentation example for: s66_initializers.md
# Validate: opcua-modeler generate --input initializers.model.yaml
#
namespaceUri: http://example.com/doc-examples/initializers/
namespaces:
  - di
version: 1.0.0

objectTypes:
  - browseName: SensorType
    components:
      - browseName: Temperature
        dataType: ua:Double
      - browseName: Pressure
        dataType: ua:Double
      - browseName: Level
        dataType: ua:Double
        typeDefinition: ua:AnalogUnitRangeType

instances:
  - browseName: Sensor1
    typeDefinition: SensorType
    organizedBy: /ua:Objects
    initializers:
      - variable: Temperature
        value: 22.5
      - variable: Pressure
        value: 1013.25

  - browseName: Sensor2
    typeDefinition: SensorType
    organizedBy: /ua:Objects
    initializers:
      - variable: Level
        value: 75.0
      - variable: Level.ua:EngineeringUnits
        value: "%"

  - browseName: Sensor3
    typeDefinition: SensorType
    organizedBy: /ua:Objects
    initializers:
      - variable: Level
        value: 42.0
        engineeringUnits: "%"
      - variable: Temperature
        value: 23.5
        engineeringUnits: "°C"

initializers:
  - variable: Sensor1/Temperature
    value: 18.0
  - variable: Sensor1/Pressure
    value: 1005.0
📄 Generated NodeSet2.xml — initializers.model.Nodeset2.xml
initializers.model.Nodeset2.xml
<?xml version="1.0"?>
<UANodeSet xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:uax="http://opcfoundation.org/UA/2008/02/Types.xsd" xmlns="http://opcfoundation.org/UA/2011/03/UANodeSet.xsd" xmlns:ns1="http://example.com/doc-examples/initializers/Type.xsd">
    <NamespaceUris>
        <Uri>http://example.com/doc-examples/initializers/</Uri>
    </NamespaceUris>
    <Models>
        <Model ModelUri="http://example.com/doc-examples/initializers/" Version="1.0.0" PublicationDate="2026-05-26T09:24:00.000Z">
            <RequiredModel ModelUri="http://opcfoundation.org/UA/" Version="1.05.06" PublicationDate="2025-11-08T00:00:00.000Z"/>
        </Model>
    </Models>
    <Aliases>
        <Alias Alias="Double">i=11</Alias>
        <Alias Alias="HasComponent">i=47</Alias>
        <Alias Alias="HasModellingRule">i=37</Alias>
        <Alias Alias="HasProperty">i=46</Alias>
        <Alias Alias="HasSubtype">i=45</Alias>
        <Alias Alias="HasTypeDefinition">i=40</Alias>
        <Alias Alias="Organizes">i=35</Alias>
        <Alias Alias="Range">i=884</Alias>
    </Aliases>
<!--ReferenceTypes-->
<!--ObjectTypes-->
<!--ObjectType - 1:SensorType {{{{ -->
    <UAObjectType NodeId="ns=1;i=1000" BrowseName="1:SensorType">
        <DisplayName>SensorType</DisplayName>
        <References>
            <Reference ReferenceType="HasSubtype" IsForward="false">i=58</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1001</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1002</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1003</Reference>
        </References>
    </UAObjectType>
    <UAVariable NodeId="ns=1;i=1001" BrowseName="1:Temperature" ParentNodeId="ns=1;i=1000" AccessLevel="3" DataType="Double">
        <DisplayName>Temperature</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
            <Reference ReferenceType="HasModellingRule">i=78</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1002" BrowseName="1:Pressure" ParentNodeId="ns=1;i=1000" AccessLevel="3" DataType="Double">
        <DisplayName>Pressure</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
            <Reference ReferenceType="HasModellingRule">i=78</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1003" BrowseName="1:Level" ParentNodeId="ns=1;i=1000" AccessLevel="3" DataType="Double">
        <DisplayName>Level</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=2368</Reference>
            <Reference ReferenceType="HasModellingRule">i=78</Reference>
            <Reference ReferenceType="HasProperty">ns=1;i=1004</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1004" BrowseName="EURange" ParentNodeId="ns=1;i=1003" AccessLevel="3" DataType="Range">
        <DisplayName>EURange</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
            <Reference ReferenceType="HasModellingRule">i=78</Reference>
        </References>
        <Value>
            <ExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
                <TypeId>
                    <Identifier>i=885</Identifier>
                </TypeId>
                <Body>
                    <Range>
                        <Low>-1</Low>
                        <High>1</High>
                    </Range>
                </Body>
            </ExtensionObject>
        </Value>
    </UAVariable>
<!--ObjectType - 1:SensorType }}}}-->
<!--VariableTypes-->
<!--Other Nodes-->
<!--Object - 1:Sensor1 {{{{ -->
    <UAObject NodeId="ns=1;i=1005" BrowseName="1:Sensor1">
        <DisplayName>Sensor1</DisplayName>
        <References>
            <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
            <Reference ReferenceType="HasTypeDefinition">ns=1;i=1000</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1006</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1007</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1008</Reference>
        </References>
    </UAObject>
    <UAVariable NodeId="ns=1;i=1006" BrowseName="1:Temperature" ParentNodeId="ns=1;i=1005" AccessLevel="3" DataType="Double">
        <DisplayName>Temperature</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
        </References>
        <Value>
            <uax:Double>18</uax:Double>
        </Value>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1007" BrowseName="1:Pressure" ParentNodeId="ns=1;i=1005" AccessLevel="3" DataType="Double">
        <DisplayName>Pressure</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
        </References>
        <Value>
            <uax:Double>1005</uax:Double>
        </Value>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1008" BrowseName="1:Level" ParentNodeId="ns=1;i=1005" AccessLevel="3" DataType="Double">
        <DisplayName>Level</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=2368</Reference>
            <Reference ReferenceType="HasProperty">ns=1;i=1009</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1009" BrowseName="EURange" ParentNodeId="ns=1;i=1008" AccessLevel="3" DataType="Range">
        <DisplayName>EURange</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
        </References>
        <Value>
            <ExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
                <TypeId>
                    <Identifier>i=885</Identifier>
                </TypeId>
                <Body>
                    <Range>
                        <Low>-1</Low>
                        <High>1</High>
                    </Range>
                </Body>
            </ExtensionObject>
        </Value>
    </UAVariable>
<!--Object - 1:Sensor1 }}}} -->
<!--Object - 1:Sensor2 {{{{ -->
    <UAObject NodeId="ns=1;i=1010" BrowseName="1:Sensor2">
        <DisplayName>Sensor2</DisplayName>
        <References>
            <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
            <Reference ReferenceType="HasTypeDefinition">ns=1;i=1000</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1011</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1012</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1013</Reference>
        </References>
    </UAObject>
    <UAVariable NodeId="ns=1;i=1011" BrowseName="1:Temperature" ParentNodeId="ns=1;i=1010" AccessLevel="3" DataType="Double">
        <DisplayName>Temperature</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1012" BrowseName="1:Pressure" ParentNodeId="ns=1;i=1010" AccessLevel="3" DataType="Double">
        <DisplayName>Pressure</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1013" BrowseName="1:Level" ParentNodeId="ns=1;i=1010" AccessLevel="3" DataType="Double">
        <DisplayName>Level</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=2368</Reference>
            <Reference ReferenceType="HasProperty">ns=1;i=1014</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1014" BrowseName="EURange" ParentNodeId="ns=1;i=1013" AccessLevel="3" DataType="Range">
        <DisplayName>EURange</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
        </References>
        <Value>
            <ExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
                <TypeId>
                    <Identifier>i=885</Identifier>
                </TypeId>
                <Body>
                    <Range>
                        <Low>-1</Low>
                        <High>1</High>
                    </Range>
                </Body>
            </ExtensionObject>
        </Value>
    </UAVariable>
<!--Object - 1:Sensor2 }}}} -->
<!--Object - 1:Sensor3 {{{{ -->
    <UAObject NodeId="ns=1;i=1015" BrowseName="1:Sensor3">
        <DisplayName>Sensor3</DisplayName>
        <References>
            <Reference ReferenceType="Organizes" IsForward="false">i=85</Reference>
            <Reference ReferenceType="HasTypeDefinition">ns=1;i=1000</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1016</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1017</Reference>
            <Reference ReferenceType="HasComponent">ns=1;i=1018</Reference>
        </References>
    </UAObject>
    <UAVariable NodeId="ns=1;i=1016" BrowseName="1:Temperature" ParentNodeId="ns=1;i=1015" AccessLevel="3" DataType="Double">
        <DisplayName>Temperature</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1017" BrowseName="1:Pressure" ParentNodeId="ns=1;i=1015" AccessLevel="3" DataType="Double">
        <DisplayName>Pressure</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=63</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1018" BrowseName="1:Level" ParentNodeId="ns=1;i=1015" AccessLevel="3" DataType="Double">
        <DisplayName>Level</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=2368</Reference>
            <Reference ReferenceType="HasProperty">ns=1;i=1019</Reference>
        </References>
    </UAVariable>
    <UAVariable NodeId="ns=1;i=1019" BrowseName="EURange" ParentNodeId="ns=1;i=1018" AccessLevel="3" DataType="Range">
        <DisplayName>EURange</DisplayName>
        <References>
            <Reference ReferenceType="HasTypeDefinition">i=68</Reference>
        </References>
        <Value>
            <ExtensionObject xmlns="http://opcfoundation.org/UA/2008/02/Types.xsd">
                <TypeId>
                    <Identifier>i=885</Identifier>
                </TypeId>
                <Body>
                    <Range>
                        <Low>-1</Low>
                        <High>1</High>
                    </Range>
                </Body>
            </ExtensionObject>
        </Value>
    </UAVariable>
<!--Object - 1:Sensor3 }}}} -->
</UANodeSet>