The NodeOPCUA API The NodeOPCUA API

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    UATwoStateVariable Class

    Extends UAVariable
    Defined in: packages\node-opcua-address-space\src\ua_two_state_variable.js:134
    Module: opcua.address_space

    Constructor

    Methods

    _clone

    (
    • Constructor
    • options
    • extraInfo
    )
    private

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1694

    Parameters:

    • Constructor Function
    • options Object
    • extraInfo Object

    Returns:

    :

    _clone_children_references

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

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1675

    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:946

    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 });

    addTwoStateVariable

    (
    • options
    )
    UATwoStateVariable

    Defined in packages\node-opcua-address-space\src\ua_two_state_variable.js:305

    Parameters:

    • options Object
      • browseName String
      • [description] String optional
      • [modellingRule] String optional
      • [minimumSamplingInterval=0] Number optional
      • componentOf Node | NodeId
      • propertyOf Node | NodeId
      • trueState String
      • falseState String
      • [isTrueSubStateOf] NodeId optional
      • [isFalseSubStateOf] NodeId optional
      • [modellingRule] optional

    Returns:

    UATwoStateVariable:

    Optionals can be EffectiveDisplayName, TransitionTime, EffectiveTransitionTime

    bindVariable

    (
    • options
    • [overwrite = false]
    )

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:1147

    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:1505

    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:1137

    Parameters:

    Returns:

    NodeId[]:

    dispose

    ()

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1884

    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:371

    Parameters:

    • strReference String

      the referenceType as a string.

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

    Returns:

    Reference:

    findReferences

    (
    • strReference
    • [isForward=true]
    )
    Array

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:325

    Parameters:

    • strReference String

      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:1116

    Returns:

    String:

    the full path name of the node

    getAggregates

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:508

    Returns:

    BaseNode[]:

    return an array with the Aggregates of this object.

    getComponentByName

    (
    • browseName
    )
    BaseNode | Null

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:574

    retrieve a component by name

    Parameters:

    • browseName Object

    Returns:

    BaseNode | Null:

    getComponents

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:519

    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:564

    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:553

    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:1959

    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:615

    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:654

    Parameters:

    • nodeId Object

    Returns:

    UAMethod | Null:

    getMethodByName

    (
    • browseName
    )
    UAMethod | Null

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:668

    Parameters:

    • browseName Object

    Returns:

    UAMethod | Null:

    getMethods

    () Array

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:625

    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:542

    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:531

    Returns:

    BaseNode[]:

    return a array with the properties of this object.

    getPropertyByName

    (
    • browseName
    )
    BaseNode | Null

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

    retrieve a property by name

    Parameters:

    • browseName Object

    Returns:

    BaseNode | Null:

    getTrueSubStates

    () BaseNode[]

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1967

    Returns:

    BaseNode[]:

    return an array with the SubStates of this object.

    getValue

    () Boolean

    Defined in packages\node-opcua-address-space\src\ua_two_state_variable.js:274

    Returns:

    Boolean:

    getValueAsString

    () String

    Defined in packages\node-opcua-address-space\src\ua_two_state_variable.js:286

    Returns:

    String:

    initialize

    (
    • options
    )
    private

    Defined in packages\node-opcua-address-space\src\ua_two_state_variable.js:144

    Parameters:

    • options Object

    normalize_referenceTypeId

    (
    • addressSpace
    • referenceTypeId
    )
    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:1334

    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:862

    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:556

    Parameters:

    • context SessionContext
    • attributeId AttributeIds
      the attributeId to read
    • indexRange NumericRange | | null
    • dataEncoding String

    Returns:

    DataValue:

    readValue

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

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:370

    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

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:1314

    Parameters:

    • context SessionContext
    • callback Function
      • err Null | Error
      • dataValue DataValue | Null

        the value read

    resolveNodeId

    (
    • nodeId
    )
    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:744

    Parameters:

    • nodeId Object

    Returns:

    NodeId:

    setValue

    (
    • boolValue
    )

    Defined in packages\node-opcua-address-space\src\ua_two_state_variable.js:255

    Parameters:

    • boolValue Boolean

    setValueFromSource

    (
    • variant
    • [statusCode ]
    • [sourceTimestamp= Now]
    )

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:648

    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 ] StatusCode optional
    • [sourceTimestamp= Now] Object optional

    unpropagate_back_references

    () private

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:979

    Undo the effect of propagate_back_references

    writeAttribute

    (
    • context
    • writeValue
    • callback
    )
    async

    Inherited from BaseNode but overwritten in packages\node-opcua-address-space\src\ua_variable.js:819

    Parameters:

    • context SessionContext
    • writeValue WriteValue
      • nodeId NodeId
      • attributeId AttributeId
      • value DataValue
      • indexRange NumericRange
    • callback Function

    writeEnumValue

    (
    • value
    )

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:461

    Parameters:

    • value String | Number

    writeValue

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

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:715

    Parameters:

    • context SessionContext
    • dataValue DataValue
    • [indexRange] NumericRange optional
    • callback Function

    Properties

    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.

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:238

    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:645

    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.

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:283

    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.

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:269

    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:1915

    subtypeOf

    NodeId

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:681

    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:480

    returns the nodeId of this node's Type Definition

    typeDefinitionObj

    BaseNode

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:494

    returns the nodeId of this node's Type Definition

    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.

    Inherited from UAVariable: packages\node-opcua-address-space\src\ua_variable.js:220

    Events

    Description_changed

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:215

    fires when the description attribute is changed.

    Event Payload:

    DisplayName_changed

    Inherited from BaseNode: packages\node-opcua-address-space\src\base_node.js:182

    fires when the displayName is changed.

    Event Payload: