The NodeOPCUA API The NodeOPCUA API

  • API Docs for Version: 0.5.4

    • APIs

    Show:

    UAVariable Class

    Extends BaseNode
    Defined in: packages\node-opcua-address-space\src\ua_variable.js:166
    Module: opcua.address_space

    A OPCUA Variable Node

    Constructor

    UAVariable

    (
    • options
    )

    Defined in packages\node-opcua-address-space\src\ua_variable.js:166

    Parameters:

    • options Object
      • value
      • browseName String
      • dataType NodeId | String
      • valueRank Int32
      • arrayDimensions Null | Array
      • accessLevel AccessLevel
      • userAccessLevel AccessLevel
      • [minimumSamplingInterval= -1] optional
      • [historizing= false] Boolean optional
      • [permissions] optional
      • parentNodeId NodeId

        The AccessLevel Attribute is used to indicate how the Value of a Variable can be accessed (read/write) and if it contains current and/or historic data. The AccessLevel does not take any user access rights into account, i.e. although the Variable is writable this may be restricted to a certain user / user group. The AccessLevel is an 8-bit unsigned integer with the structure defined in the following table:

        Field Bit Description CurrentRead 0 Indicates if the current value is readable (0 means not readable, 1 means readable). CurrentWrite 1 Indicates if the current value is writable (0 means not writable, 1 means writable). HistoryRead 2 Indicates if the history of the value is readable (0 means not readable, 1 means readable). HistoryWrite 3 Indicates if the history of the value is writable (0 means not writable, 1 means writable). SemanticChange 4 Indicates if the Variable used as Property generates SemanticChangeEvents (see 9.31). Reserved 5:7 Reserved for future use. Shall always be zero.

        The first two bits also indicate if a current value of this Variable is available and the second two bits indicates if the history of the Variable is available via the OPC UA server.

    Methods

    _clone

    (
    • Constructor
    • options
    • extraInfo
    • optionalFilter
    )
    private

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1928

    Parameters:

    • Constructor Function
    • options Object
    • extraInfo Object
    • optionalFilter Object

    Returns:

    :

    _clone_children_references

    (
    • newParent
    • [optionalFilter = null]
    • [extraInfo]
    )
    Array private

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1909

    clone properties and methods

    Parameters:

    • newParent Object

      the new parent object to which references of type HasChild will be attached

    • [optionalFilter = null] Function optional

      a filter

    • [extraInfo] Object optional

    Returns:

    Array:

    addReference

    (
    • reference
    )

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1076

    Parameters:

    • reference Object
      • referenceType String
      • [isForward= true] Boolean optional
      • nodeId Node | NodeId | String

    Example:

    view.addReference({ referenceType: "Organizes", nodeId: myDevice });

    or

    myDevice1.addReference({ referenceType: "OrganizedBy", nodeId: view });

    bindExtensionObject

    (
    • [optionalExtensionObject=null]
    )
    ExtensionObject

    Defined in packages\node-opcua-address-space\src\ua_variable.js:1528

    Parameters:

    • [optionalExtensionObject=null] ExtensionObject optional

    Returns:

    ExtensionObject:

    bindVariable

    (
    • options
    • [overwrite = false]
    )

    Defined in packages\node-opcua-address-space\src\ua_variable.js:1211

    bind a variable with a get and set functions.

    Parameters:

    • options Object
      • [dataType=null] DataType optional

        the nodeId of the dataType

      • [accessLevel] Number optional

        AccessLevelFlagItem

      • [userAccessLevel] Number optional

        AccessLevelFlagItem

      • [set] Function optional

        the variable setter function

      • [get] Function optional

        the variable getter function. the function must return a Variant or a status code

      • [timestamped_get] Function optional

        the getter function. this function must return a object with the following

      • [historyRead] Function optional

        properties:

        • value: a Variant or a status code
        • sourceTimestamp
        • sourcePicoseconds
      • [timestamped_set] Function optional
      • [refreshFunc] Function optional

        the variable asynchronous getter function.

    • [overwrite = false] Boolean optional

      set overwrite to true to overwrite existing binding

    Returns:

    void

    Providing read access to the underlying value

    Variation 1

    In this variation, the user provides a function that returns a Variant with the current value.

    The sourceTimestamp will be set automatically.

    The get function is called synchronously.

    Example:

        ...
                        var options =  {
                          get : function() {
                             return new Variant({...});
                          },
                          set : function(variant) {
                             // store the variant somewhere
                             return StatusCodes.Good;
                          }
                       };
                       ...
                       engine.bindVariable(nodeId,options):
                       ...

    Variation 2:

    This variation can be used when the user wants to specify a specific '''sourceTimestamp''' associated with the current value of the UAVariable.

    The provided timestamped_get function should return an object with three properties:

    • value: containing the variant value or a error StatusCode,
    • sourceTimestamp
    • sourcePicoseconds
    ...
                    var myDataValue = new DataValue({
                      value: {dataType: DataType.Double , value: 10.0},
                      sourceTimestamp : new Date(),
                      sourcePicoseconds: 0
                    });
                    ...
                    var options =  {
                      timestamped_get : function() { return myDataValue;  }
                    };
                    ...
                    engine.bindVariable(nodeId,options):
                    ...
                    // record a new value
                    myDataValue.value.value = 5.0;
                    myDataValue.sourceTimestamp = new Date();
                    ...

    Variation 3:

    This variation can be used when the value associated with the variables requires a asynchronous function call to be extracted. In this case, the user should provide an async method refreshFunc.

    The refreshFunc shall do whatever is necessary to fetch the most up to date version of the variable value, and call the callback function when the data is ready.

    The callback function follow the standard callback function signature:

    • the first argument shall be null or Error, depending of the outcome of the fetch operation,
    • the second argument shall be a DataValue with the new UAVariable Value, a StatusCode, and time stamps.

    Optionally, it is possible to pass a sourceTimestamp and a sourcePicoseconds value as a third and fourth arguments of the callback. When sourceTimestamp and sourcePicoseconds are missing, the system will set their default value to the current time..

    ...
                    var options =  {
                       refreshFunc : function(callback) {
                         ... do_some_async_stuff_to_get_the_new_variable_value
                         var dataValue = new DataValue({
                             value: new Variant({...}),
                             statusCode: StatusCodes.Good,
                             sourceTimestamp: new Date()
                         });
                         callback(null,dataValue);
                       }
                    };
                    ...
                    variable.bindVariable(nodeId,options):
                    ...

    Providing write access to the underlying value

    Variation1 - provide a simple synchronous set function

    Notes

    to do : explain return StatusCodes.GoodCompletesAsynchronously;

    browseNode

    (
    • browseDescription
    • session
    )
    ReferenceDescription[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1700

    browse the node to extract information requested in browseDescription

    Parameters:

    Returns:

    ReferenceDescription[]:

    browseNodeByTargetName

    (
    • relativePathElement
    )
    NodeId[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1326

    Parameters:

    Returns:

    NodeId[]:

    dispose

    ()

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:2137

    the dispose method should be called when the node is no longer used, to release back pointer to the address space and clear caches.

    findReference

    (
    • strReference
    • [isForward]
    • [optionalSymbolicName]
    )
    Reference

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:425

    Parameters:

    • strReference String

      the referenceType as a string.

    • [isForward] Boolean | Null optional
    • [optionalSymbolicName] String optional

    Returns:

    Reference:

    findReferences

    (
    • referenceType
    • [isForward=true]
    )
    Array

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:377

    Parameters:

    • referenceType String | NodeId | ReferenceType

      the referenceType as a string.

    • [isForward=true] Boolean optional

    Returns:

    Array:

    full_name

    () String

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1294

    Returns:

    String:

    the full path name of the node

    getAggregates

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:576

    Returns:

    BaseNode[]:

    return an array with the Aggregates of this object.

    getComponentByName

    (
    • browseName
    • [namespaceIndex=null]
    )
    BaseNode | Null

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:656

    retrieve a component by name

    Parameters:

    • browseName Object
    • [namespaceIndex=null] Object optional

    Returns:

    BaseNode | Null:

    getComponents

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:589

    Returns:

    BaseNode[]:

    return an array with the components of this object.

    getEventSourceOfs

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:642

    Returns:

    BaseNode[]:

    return a array of the objects for which this node is an EventSource

    getEventSources

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:629

    Returns:

    BaseNode[]:

    return a array with the event source of this object.

    getFalseSubStates

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:2216

    Returns:

    BaseNode[]:

    return an array with the SubStates of this object.

    getFolderElements

    () Array

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:699

    returns the list of nodes that this folder object organizes

    Returns:

    Array:

    getMethodById

    (
    • nodeId
    )
    UAMethod | Null

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:739

    Parameters:

    • nodeId Object

    Returns:

    UAMethod | Null:

    getMethodByName

    (
    • browseName
    • [namespaceIndex=null]
    )
    UAMethod | Null

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:767

    Parameters:

    • browseName Object
    • [namespaceIndex=null] Object optional

    Returns:

    UAMethod | Null:

    getMethods

    () Array

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:709

    returns the list of methods that this object provides

    Returns:

    Array:

    returns an array wit"h Method objects.

    Note: internally, methods are special types of components

    getNotifiers

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:616

    Returns:

    BaseNode[]:

    return a array with the notifiers of this object.

    getProperties

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:603

    Returns:

    BaseNode[]:

    return a array with the properties of this object.

    getPropertyByName

    (
    • browseName
    • [namespaceIndex=null]
    )
    BaseNode | Null

    Inherited from BaseNode but overwritten in packages\node-opcua-address-space\src\base_node.js:670

    retrieve a property by name

    Parameters:

    • browseName Object
    • [namespaceIndex=null] Object optional

    Returns:

    BaseNode | Null:

    getTrueSubStates

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:2224

    Returns:

    BaseNode[]:

    return an array with the SubStates of this object.

    isArgumentValid

    (
    • addressSpace
    • argDefinition
    • arg
    )
    Boolean private

    Inherited from BaseNode: packages\node-opcua-address-space\src\argument_list.js:149

    Parameters:

    Returns:

    Boolean:

    isReadable

    (
    • context
    )
    Boolean

    Defined in packages\node-opcua-address-space\src\ua_variable.js:322

    Parameters:

    • context SesionContext

    Returns:

    Boolean:

    isUserReadable

    (
    • context
    )
    Boolean

    Defined in packages\node-opcua-address-space\src\ua_variable.js:333

    Parameters:

    • context SesionContext

    Returns:

    Boolean:

    isUserWritable

    (
    • context
    )
    Boolean

    Defined in packages\node-opcua-address-space\src\ua_variable.js:360

    Parameters:

    Returns:

    Boolean:

    isValueInRange note: this method is overridden in address-space-data-access

    () StatusCode

    Defined in packages\node-opcua-address-space\src\ua_variable.js:712

    Returns:

    StatusCode:

    isWritable

    (
    • context
    )
    Boolean

    Defined in packages\node-opcua-address-space\src\ua_variable.js:349

    Parameters:

    Returns:

    Boolean:

    normalize_referenceTypeId

    (
    • addressSpace
    • referenceTypeId
    )
    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1529

    Parameters:

    • addressSpace AddressSpace
    • referenceTypeId String | NodeId | Null

      : the referenceType either as a string or a nodeId

    Returns:

    NodeId:

    propagate_back_references

    ()

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:984

    this methods propagates the forward references to the pointed node by inserting backward references to the counter part node

    readAttribute

    (
    • context
    • attributeId
    • indexRange
    • dataEncoding
    )
    DataValue

    Inherited from BaseNode but overwritten in packages\node-opcua-address-space\src\ua_variable.js:563

    Parameters:

    Returns:

    DataValue:

    readValue

    (
    • [context]
    • [indexRange]
    • [dataEncoding]
    )
    DataValue

    Defined in packages\node-opcua-address-space\src\ua_variable.js:377

    Parameters:

    • [context] SessionContext optional
    • [indexRange] NumericRange | Null optional
    • [dataEncoding] String optional

    Returns:

    DataValue:

    from OPC.UA.Spec 1.02 part 4 5.10.2.4 StatusCodes Table 51 defines values for the operation level statusCode contained in the DataValue structure of each values element. Common StatusCodes are defined in Table 166. Table 51 Read Operation Level Result Codes Symbolic Id Description BadNodeIdInvalid The syntax of the node id is not valid. BadNodeIdUnknown The node id refers to a node that does not exist in the server address space. BadAttributeIdInvalid Bad_AttributeIdInvalid The attribute is not supported for the specified node. BadIndexRangeInvalid The syntax of the index range parameter is invalid. BadIndexRangeNoData No data exists within the range of indexes specified. BadDataEncodingInvalid The data encoding is invalid. This result is used if no dataEncoding can be applied because an Attribute other than Value was requested or the DataType of the Value Attribute is not a subtype of the Structure DataType. BadDataEncodingUnsupported The server does not support the requested data encoding for the node. This result is used if a dataEncoding can be applied but the passed data encoding is not known to the Server. BadNotReadable The access level does not allow reading or subscribing to the Node. BadUserAccessDenied User does not have permission to perform the requested operation. (table 165)

    readValueAsync

    (
    • context
    • callback
    )
    async

    Defined in packages\node-opcua-address-space\src\ua_variable.js:1378

    Parameters:

    removeReference

    (
    • reference
    )

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1109

    Parameters:

    • reference Object

    Returns:

    void

    resolveNodeId

    (
    • nodeId
    )
    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:851

    Parameters:

    • nodeId Object

    Returns:

    NodeId:

    setValueFromSource

    (
    • variant
    • [statusCode = StatusCodes.Good]
    • [sourceTimestamp= Now]
    )

    Defined in packages\node-opcua-address-space\src\ua_variable.js:655

    setValueFromSource is used to let the device sets the variable values this method also records the current time as sourceTimestamp and serverTimestamp. the method broadcasts an "value_changed" event

    Parameters:

    • variant Variant
    • [statusCode = StatusCodes.Good] StatusCode optional
    • [sourceTimestamp= Now] Object optional

    touchValue touch the source timestamp of a Variable and cascade up the change to the parent variable if any.

    (
    • [optionalNow=null]
    )

    Defined in packages\node-opcua-address-space\src\ua_variable.js:1146

    Parameters:

    • [optionalNow=null] Object optional
      • timestamp Date
      • picoseconds Number

    unpropagate_back_references

    () private

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1155

    Undo the effect of propagate_back_references

    verifyArguments_ArgumentList

    (
    • addressSpace
    • methodInputArguments
    • inputArguments
    )

    Inherited from BaseNode: packages\node-opcua-address-space\src\argument_list.js:202

    Parameters:

    Returns:

    statusCode,inputArgumentResults

    writeAttribute

    (
    • context
    • writeValue
    • callback
    )
    async

    Inherited from BaseNode but overwritten in packages\node-opcua-address-space\src\ua_variable.js:866

    Parameters:

    writeEnumValue

    (
    • value
    )

    Defined in packages\node-opcua-address-space\src\ua_variable.js:468

    Parameters:

    • value String | Number

    writeValue

    (
    • context
    • dataValue
    • [indexRange]
    • callback
    )
    async

    Defined in packages\node-opcua-address-space\src\ua_variable.js:759

    Parameters:

    Properties

    accessLevel

    number The AccessLevel Attribute is used to indicate how the Value of a Variable can be accessed (read/write) and if it contains current and/or historic data. The AccessLevel does not take any user access rights into account, i.e. although the Variable is writable this may be restricted to a certain user / user group. The AccessLevelType is defined in 8.57.

    Defined in packages\node-opcua-address-space\src\ua_variable.js:257

    arrayDimensions

    number UInt32 The Attribute is intended to describe the capability of the Variable, not the current size. The number of elements shall be equal to the value of the ValueRank Attribute. Shall be null if ValueRank ? 0. A value of 0 for an individual dimension indicates that the dimension has a variable length. For example, if a Variable is defined by the following C array: Int32 myArray[346]; then this Variables DataType would point to an Int32, the Variable�s ValueRank has the value 1 and the ArrayDimensions is an array with one entry having the value 346. Note that the maximum length of an array transferred on the wire is 2147483647 (max Int32) and a multidimentional array is encoded as a one dimensional array.

    Defined in packages\node-opcua-address-space\src\ua_variable.js:239

    This Attribute specifies the length of each dimension for an array value. T

    hasMethods

    Boolean

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:730

    returns true if the object has some opcua methods

    historizing

    Boolean This differs from the AccessLevel Attribute which identifies if the Variable has any historical data. A value of TRUE indicates that the Server is actively collecting data. A value of FALSE indicates the Server is not actively collecting data. Default value is FALSE.

    Defined in packages\node-opcua-address-space\src\ua_variable.js:290

    The Historizing Attribute indicates whether the Server is actively collecting data for the history of the Variable.

    minimumSamplingInterval

    number Optional It specifies (in milliseconds) how fast the Server can reasonably sample the value for changes (see Part 4 for a detailed description of sampling interval). A MinimumSamplingInterval of 0 indicates that the Server is to monitor the item continuously. A MinimumSamplingInterval of -1 means indeterminate.

    Defined in packages\node-opcua-address-space\src\ua_variable.js:276

    The MinimumSamplingInterval Attribute indicates how 'current' the Value of the Variable will be kept.

    modellingRule

    String | Undefined

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:2172

    subtypeOf

    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:781

    returns the nodeId of the Type which is the super type of this

    typeDefinition

    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:544

    returns the nodeId of this node's Type Definition

    typeDefinitionObj

    BaseNode

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:560

    returns the nodeId of this node's Type Definition

    userAccessLevel

    number The UserAccessLevel Attribute is used to indicate how the Value of a Variable can be accessed (read/write) and if it contains current or historic data taking user access rights into account. The AccessLevelType is defined in 8.57.

    Defined in packages\node-opcua-address-space\src\ua_variable.js:267

    valueRank

    number UInt32 This Attribute indicates whether the Value Attribute of the Variable is an array and how many dimensions the array has. It may have the following values: n > 1: the Value is an array with the specified number of dimensions. OneDimension (1): The value is an array with one dimension. OneOrMoreDimensions (0): The value is an array with one or more dimensions. Scalar (?1): The value is not an array. Any (?2): The value can be a scalar or an array with any number of dimensions. ScalarOrOneDimension (?3): The value can be a scalar or a one dimensional array. NOTE All DataTypes are considered to be scalar, even if they have array-like semantics like ByteString and String.

    Defined in packages\node-opcua-address-space\src\ua_variable.js:221

    Events

    Description_changed

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:229

    fires when the description attribute is changed.

    Event Payload:

    DisplayName_changed

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:191

    fires when the displayName is changed.

    Event Payload: