Parameters
- serverDescriptor
- The OPC server involved in the operation.
- parentNodeDescriptor
- Descriptor for the parent branch to be browsed (can be the root).
- browseParameters
- Contains filtering conditions.
OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.DataAccess.ComTypes Namespace > _EasyDAClient Interface : BrowseNodes Method |
[ElementsNotNull()] [NotNull()] DANodeElementCollection BrowseNodes( object serverDescriptor, object parentNodeDescriptor, object browseParameters )
[ElementsNotNull()] [NotNull()] DANodeElementCollection^ BrowseNodes( Object^ serverDescriptor, Object^ parentNodeDescriptor, Object^ browseParameters )
'Declaration
<ElementsNotNullAttribute()> <NotNullAttribute()> Function BrowseNodes( _ ByVal serverDescriptor As Object, _ ByVal parentNodeDescriptor As Object, _ ByVal browseParameters As Object _ ) As DANodeElementCollection
'Usage
Dim instance As _EasyDAClient Dim serverDescriptor As Object Dim parentNodeDescriptor As Object Dim browseParameters As Object Dim value As DANodeElementCollection value = instance.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters)
Exception | Description |
---|---|
System.ArgumentNullException |
A This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception. |
OpcLabs.EasyOpc.OperationModel.OpcException | The OPC "Classic" (or OPC XML-DA) operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause. This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately. |
// This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays // whether the node is a branch or a leaf. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class BrowseNodes { public static void Main1() { // Instantiate the client object. var client = new EasyDAClient(); DANodeElementCollection nodeElements; try { nodeElements = client.BrowseNodes("", "OPCLabs.KitServer.2", "Greenhouse", DABrowseParameters.Default); } catch (OpcException opcException) { Console.WriteLine($"*** Failure: {opcException.GetBaseException().Message}"); return; } foreach (DANodeElement nodeElement in nodeElements) { Console.WriteLine($"NodeElements(\"{nodeElement.Name}\"):"); Console.WriteLine($" .IsBranch: {nodeElement.IsBranch}"); Console.WriteLine($" .IsLeaf: {nodeElement.IsLeaf}"); } } } }
# This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays # whether the node is a branch or a leaf. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . #requires -Version 5.1 using namespace OpcLabs.EasyOpc.OperationModel using namespace OpcLabs.EasyOpc.DataAccess # The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows . Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcClassicCore.dll" Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcClassic.dll" Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcClassicComponents.dll" # Instantiate the client object. $client = New-Object EasyDAClient try { $nodeElements = [IEasyDAClientExtension]::BrowseNodes($client, "", "OPCLabs.KitServer.2", "Greenhouse", [DABrowseParameters]::Default) } catch [OpcException] { Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)" return } Foreach ($nodeElement in $nodeElements) { Write-Host "NodeElements(`"$($nodeElement.Name)`"):" Write-Host " .IsBranch: $($nodeElement.IsBranch)" Write-Host " .IsLeaf: $($nodeElement.IsLeaf)" }
# This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays # whether the node is a branch or a leaf. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc # Import .NET namespaces. from OpcLabs.EasyOpc.DataAccess import * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object client = EasyDAClient() # Perform the operation try: nodeElements = IEasyDAClientExtension.BrowseNodes(client, '', 'OPCLabs.KitServer.2', 'Greenhouse', DABrowseParameters.Default) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message) exit() # Display results for nodeElement in nodeElements: print('NodeElements("' + nodeElement.Name + '"):') print(' .IsBranch:', nodeElement.IsBranch) print(' .IsLeaf:', nodeElement.IsLeaf) # Example output: # #NodeElements("Register_ArrayOfI1"): # .IsBranch: False # .IsLeaf: True #NodeElements("Register_ArrayOfI2"): # .IsBranch: False # .IsLeaf: True #NodeElements("Register_ArrayOfI4"): # .IsBranch: False # .IsLeaf: True #NodeElements("Staircase 0:2 (10 s)"): # .IsBranch: False # .IsLeaf: True #NodeElements("Constant_VARIANT"): # .IsBranch: False # .IsLeaf: True #...
' This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays ' whether the node is a branch or a leaf. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class BrowseNodes Shared Sub Main1() Dim client = New EasyDAClient() Dim nodeElements As DANodeElementCollection Try nodeElements = client.BrowseNodes("", "OPCLabs.KitServer.2", "Greenhouse", DABrowseParameters.Default) Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try For Each nodeElement In nodeElements Console.WriteLine($"NodeElements(""{nodeElement.Name}""):") Console.WriteLine($" .IsBranch: {nodeElement.IsBranch}") Console.WriteLine($" .IsLeaf: {nodeElement.IsLeaf}") Next nodeElement End Sub End Class End Namespace
// This example shows how to obtain data types of leaves in the OPC-DA address // space by browsing and filtering, i.e. without the use of OPC properties. // This technique allows determining the data types with servers that only // support OPC-DA 1.0. It can also be more effective than the use of // GetMultiplePropertyValues, if there is large number of leaves, and // relatively small number of data types to be checked. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using System.Collections.Generic; using OpcLabs.BaseLib.ComInterop; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class BrowseNodes { public static void DataTypes() { // Instantiate the client object. var client = new EasyDAClient(); // Define the list of data types we will be checking for. // Change as needed for your application. // This technique is only usable if there is a known list of // data types you are interested in. If you are interested in // all leaves, even those that are of data types not explicitly // listed, always include VarTypes.Empty as the first data type. // The leaves of "unlisted" data types will have VarTypes.Empty // associated with them. var dataTypes = new VarType[] { VarTypes.Empty, VarTypes.I2, VarTypes.R4 }; // For each leaf found, this dictionary wil hold its associated data type. var dataTypeDictionary = new Dictionary<DANodeElement, VarType>(); // For each data type, browse for leaves of this data type. foreach (VarType dataType in dataTypes) { var browseParameters = new DABrowseParameters(DABrowseFilter.Leaves, "", "", dataType); DANodeElementCollection nodeElements; try { nodeElements = client.BrowseNodes("", "OPCLabs.KitServer.2", "Greenhouse", browseParameters); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } // Store the leaf information into the dictionary, and // associate the current data type with it. foreach (var nodeElement in nodeElements) dataTypeDictionary[nodeElement] = dataType; } // Display each leaf found, and its associated data type. foreach (KeyValuePair<DANodeElement, VarType> pair in dataTypeDictionary) { DANodeElement nodeElement = pair.Key; VarType dataType = pair.Value; Console.WriteLine("{0}: {1}", nodeElement, dataType); } } } }
# This example shows how to obtain data types of leaves in the OPC-DA address # space by browsing and filtering, i.e. without the use of OPC properties. # This technique allows determining the data types with servers that only # support OPC-DA 1.0. It can also be more effective than the use of # GetMultiplePropertyValues, if there is large number of leaves, and # relatively small number of data types to be checked. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc # Import .NET namespaces. from OpcLabs.BaseLib.ComInterop import * from OpcLabs.EasyOpc.DataAccess import * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object. client = EasyDAClient() # Define the list of data types we will be checking for. # Change as needed for your application. # This technique is only usable if there is a known list of # data types you are interested in. If you are interested in # all leaves, even those that are of data types not explicitly # listed, always include VarTypes.Empty as the first data type. # The leaves of "unlisted" data types will have VarTypes.Empty # associated with them. dataTypes = [VarType(VarTypes.Empty), VarType(VarTypes.I2), VarType(VarTypes.R4)] # For each leaf found, this dictionary wil hold its associated data type. dataTypeDictionary = {} # For each data type, browse for leaves of this data type. for dataType in dataTypes: browseParameters = DABrowseParameters(DABrowseFilter.Leaves, '', '', dataType) try: nodeElements = IEasyDAClientExtension.BrowseNodes(client, '', 'OPCLabs.KitServer.2', 'Greenhouse', browseParameters) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message) exit() # Store the leaf information into the dictionary, and # associate the current data type with it. for nodeElement in nodeElements: dataTypeDictionary[nodeElement] = dataType # Display each leaf found, and its associated data type. for nodeElement, dataType in dataTypeDictionary.items(): print(nodeElement, ': ', dataType, sep='')
' This example shows how to obtain data types of leaves in the OPC-DA address ' space by browsing and filtering, i.e. without the use of OPC properties. ' This technique allows determining the data types with servers that only ' support OPC-DA 1.0. It can also be more effective than the use of ' GetMultiplePropertyValues, if there is large number of leaves, and ' relatively small number of data types to be checked. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports OpcLabs.BaseLib.ComInterop Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class BrowseNodes Shared Sub DataTypes() Dim client = New EasyDAClient() ' Define the list of data types we will be checking for. ' Change as needed for your application. ' This technique is only usable if there is a known list of ' data types you are interested in. If you are interested in ' all leaves, even those that are of data types not explicitly ' listed, always include VarTypes.Empty as the first data type. ' The leaves of "unlisted" data types will have VarTypes.Empty ' associated with them. Dim dataTypes() = New VarType() {VarTypes.Empty, VarTypes.I2, VarTypes.R4} ' For each leaf found, this dictionary wil hold its associated data type. Dim dataTypeDictionary = New Dictionary(Of DANodeElement, VarType)() ' For each data type, browse for leaves of this data type. For Each dataType As VarType In dataTypes Dim browseParameters = New DABrowseParameters(DABrowseFilter.Leaves, "", "", dataType) Dim nodeElements As DANodeElementCollection Try nodeElements = client.BrowseNodes("", "OPCLabs.KitServer.2", "Greenhouse", browseParameters) Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try ' Store the leaf information into the dictionary, and ' associate the current data type with it. For Each nodeElement In nodeElements dataTypeDictionary(nodeElement) = dataType Next nodeElement Next dataType For Each pair In dataTypeDictionary Dim nodeElement As DANodeElement = pair.Key Dim dataType As VarType = pair.Value Console.WriteLine("{0}: {1}", nodeElement, dataType) Next pair End Sub End Class End Namespace
// This example shows how to recursively browse the nodes in the OPC address space. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using System.Diagnostics; using OpcLabs.EasyOpc; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class BrowseNodes { public static void Recursive() { var stopwatch = new Stopwatch(); stopwatch.Start(); // Instantiate the client object. var client = new EasyDAClient(); _branchCount = 0; _leafCount = 0; try { BrowseFromNode(client, "OPCLabs.KitServer.2", ""); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } stopwatch.Stop(); Console.WriteLine("Browsing has taken (milliseconds): {0}", stopwatch.ElapsedMilliseconds); Console.WriteLine("Branch count: {0}", _branchCount); Console.WriteLine("Leaf count: {0}", _leafCount); } private static void BrowseFromNode( EasyDAClient client, ServerDescriptor serverDescriptor, DANodeDescriptor parentNodeDescriptor) { Debug.Assert(client != null); Debug.Assert(serverDescriptor != null); Debug.Assert(parentNodeDescriptor != null); // Obtain all node elements under parentNodeDescriptor var browseParameters = new DABrowseParameters(); // no filtering whatsoever DANodeElementCollection nodeElementCollection = client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters); // Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for // it, here omitted for brevity. foreach (DANodeElement nodeElement in nodeElementCollection) { Debug.Assert(nodeElement != null); Console.WriteLine(nodeElement); // If the node is a branch, browse recursively into it. if (nodeElement.IsBranch) { _branchCount++; BrowseFromNode(client, serverDescriptor, nodeElement); } else { _leafCount++; } } } private static int _branchCount; private static int _leafCount; } }
# This example shows how to recursively browse the nodes in the OPC address space. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc import timeit # Import .NET namespaces. from OpcLabs.EasyOpc import * from OpcLabs.EasyOpc.DataAccess import * from OpcLabs.EasyOpc.OperationModel import * def browseFromNode(client, serverDescriptor, parentNodeDescriptor): global branchCount global leafCount assert client is not None assert serverDescriptor is not None assert parentNodeDescriptor is not None # Obtain all node elements under parentNodeDescriptor. browseParameters = DABrowseParameters() # no filtering whatsoever nodeElementCollection = client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters) # BrowseNodes(...) may also throw OpcException; here it is handled by the caller. for nodeElement in nodeElementCollection: assert nodeElement is not None print(nodeElement) # If the node is a branch, browse recursively into it. if nodeElement.IsBranch: branchCount = branchCount + 1 browseFromNode(client, serverDescriptor, DANodeDescriptor(nodeElement)) else: leafCount = leafCount + 1 beginTime = timeit.default_timer() # Instantiate the client object. client = EasyDAClient() branchCount = 0 leafCount = 0 try: browseFromNode(client, ServerDescriptor('OPCLabs.KitServer.2'), DANodeDescriptor('')) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message) exit() endTime = timeit.default_timer() print() print('Browsing has taken (milliseconds): ',(endTime - beginTime)*1000) print('Branch count: ', branchCount); print('Leaf count: ', leafCount);
' This example shows how to recursively browse the nodes in the OPC address space. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports OpcLabs.EasyOpc Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class BrowseNodes Shared Sub Recursive() Dim stopwatch = New Stopwatch() stopwatch.Start() Dim client = New EasyDAClient() _branchCount = 0 _leafCount = 0 Try BrowseFromNode(client, "OPCLabs.KitServer.2", "") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try stopwatch.Stop() Console.WriteLine("Browsing has taken (milliseconds): {0}", stopwatch.ElapsedMilliseconds) Console.WriteLine("Branch count: {0}", _branchCount) Console.WriteLine("Leaf count: {0}", _leafCount) End Sub Private Shared Sub BrowseFromNode( _ client As EasyDAClient, serverDescriptor As ServerDescriptor, parentNodeDescriptor As DANodeDescriptor) Debug.Assert(client IsNot Nothing) Debug.Assert(serverDescriptor IsNot Nothing) Debug.Assert(parentNodeDescriptor IsNot Nothing) ' Obtain all node elements under parentNodeDescriptor Dim browseParameters = New DABrowseParameters() ' no filtering whatsoever Dim nodeElementCollection As DANodeElementCollection = client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters) ' Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for ' it, here omitted for brevity. For Each nodeElement As DANodeElement In nodeElementCollection Debug.Assert(nodeElement IsNot Nothing) Console.WriteLine(nodeElement) ' If the node is a branch, browse recursively into it. If nodeElement.IsBranch Then _branchCount += 1 BrowseFromNode(client, serverDescriptor, nodeElement) Else _leafCount += 1 End If Next nodeElement End Sub Private Shared _branchCount As Integer Private Shared _leafCount As Integer End Class End Namespace
// Recursively browses and displays the nodes in the OPC address space, and attempts to read and display values of all OPC // items it finds. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using System.Diagnostics; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class BrowseNodes { const string ServerClass = "OPCLabs.KitServer.2"; // Instantiate the client object. static readonly EasyDAClient Client = new EasyDAClient(); static void BrowseAndReadFromNode(string parentItemId) { // Obtain all node elements under parentItemId var browseParameters = new DABrowseParameters(); // no filtering whatsoever DANodeElementCollection nodeElementCollection = Client.BrowseNodes("", ServerClass, parentItemId, browseParameters); // Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for it, here // omitted for brevity. foreach (DANodeElement nodeElement in nodeElementCollection) { Debug.Assert(nodeElement != null); // If the node is a leaf, it might be possible to read from it if (nodeElement.IsLeaf) { // Determine what the display - either the value read, or exception message in case of failure. string display; try { object value = Client.ReadItemValue("", ServerClass, nodeElement); display = $"{value}"; } catch (OpcException exception) { display = $"** {exception.GetBaseException().Message} **"; } Console.WriteLine("{0} -> {1}", nodeElement.ItemId, display); } // If the node is not a leaf, just display its itemId else Console.WriteLine("{0}", nodeElement.ItemId); // If the node is a branch, browse recursively into it. if (nodeElement.IsBranch && (nodeElement.ItemId != "SimulateEvents") /* this branch is too big for the purpose of this example */) BrowseAndReadFromNode(nodeElement); } } public static void RecursiveWithRead() { Console.WriteLine("Browsing and reading values..."); // Set timeout to only wait 1 second - default would be 1 minute to wait for good quality that may never come. Client.InstanceParameters.Timeouts.ReadItem = 1000; // Do the actual browsing and reading, starting from root of OPC address space (denoted by empty string for itemId) try { BrowseAndReadFromNode(""); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); } } } }
# Recursively browses and displays the nodes in the OPC address space, and attempts to read and display values of all # OPC items it finds. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc # Import .NET namespaces. from OpcLabs.EasyOpc import * from OpcLabs.EasyOpc.DataAccess import * from OpcLabs.EasyOpc.OperationModel import * SERVER_CLASS = 'OPCLabs.KitServer.2' def browseAndReadFromNode(parentItemId): global client # # Obtain all node elements under parentItemId. browseParameters = DABrowseParameters() # no filtering whatsoever nodeElementCollection = client.BrowseNodes(ServerDescriptor(SERVER_CLASS), DANodeDescriptor(parentItemId), browseParameters) # BrowseNodes(...) may also throw OpcException; here it is handled by the caller. # for nodeElement in nodeElementCollection: assert nodeElement is not None print(nodeElement) # If the node is a leaf, it might be possible to read from it. if nodeElement.IsLeaf: # Determine what to display - either the value read, or exception message in case of failure. try: value = IEasyDAClientExtension.ReadItemValue(client, '', SERVER_CLASS, nodeElement.ItemId) display = value except OpcException as opcException: display = '** ' + opcException.GetBaseException().Message + ' **' # print(nodeElement.ItemId, ' -> ', display, sep='') # If the node is not a leaf, just display its itemId. else: print(nodeElement.ItemId) # If the node is a branch, browse recursively into it. if nodeElement.IsBranch and nodeElement.ItemId != 'SimulateEvents': # this branch is too big for the purpose of this example browseAndReadFromNode(nodeElement.ItemId) # Instantiate the client object. client = EasyDAClient('Browsing and reading values...') print('Browsing and reading values...') # Do the actual browsing and reading, starting from root of OPC address space (denoted by empty string for itemId). try: browseAndReadFromNode('') except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message) exit() print() print('Finished.')
' Recursively browses and displays the nodes in the OPC address space, and attempts to read and display values of all OPC ' items it finds. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class BrowseNodes Private Const ServerClass As String = "OPCLabs.KitServer.2" Private Shared ReadOnly Client As New EasyDAClient() Private Shared Sub BrowseAndReadFromNode(parentItemId As String) ' Obtain all node elements under parentItemId Dim browseParameters = New DABrowseParameters() ' no filtering whatsoever Dim nodeElementCollection As DANodeElementCollection = Client.BrowseNodes("", ServerClass, parentItemId, browseParameters) ' Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for it, here ' omitted for brevity. For Each nodeElement As DANodeElement In nodeElementCollection Debug.Assert(nodeElement IsNot Nothing) ' If the node is a leaf, it might be possible to read from it If nodeElement.IsLeaf Then ' Determine what the display - either the value read, or exception message in case of failure. Dim display As String Try Dim value As Object = Client.ReadItemValue("", ServerClass, nodeElement.ItemId) display = String.Format("{0}", value) Catch exception As OpcException display = String.Format("** {0} **", exception.GetBaseException().Message) End Try Console.WriteLine("{0} -> {1}", nodeElement.ItemId, display) ' If the node is not a leaf, just display its itemId Else Console.WriteLine("{0}", nodeElement.ItemId) End If ' If the node is a branch, browse recursively into it. If nodeElement.IsBranch AndAlso (nodeElement.ItemId <> "SimulateEvents") Then ' this branch is too big for the purpose of this example BrowseAndReadFromNode(nodeElement.ItemId) End If Next nodeElement End Sub Shared Sub RecursiveWithRead() Console.WriteLine("Browsing and reading values...") ' Set timeout to only wait 1 second - default would be 1 minute to wait for good quality that may never come. Client.InstanceParameters.Timeouts.ReadItem = 1000 ' Do the actual browsing and reading, starting from root of OPC address space (denoted by empty string for itemId) Try BrowseAndReadFromNode("") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try End Sub End Class End Namespace
// This example shows how to recursively browse the nodes in the OPC XML-DA address space. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . using System; using System.Diagnostics; using OpcLabs.EasyOpc; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess.Xml { class BrowseNodes { public static void RecursiveXml() { var stopwatch = new Stopwatch(); stopwatch.Start(); // Instantiate the client object. var client = new EasyDAClient(); _branchCount = 0; _leafCount = 0; try { BrowseFromNode(client, "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", ""); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } stopwatch.Stop(); Console.WriteLine("Browsing has taken (milliseconds): {0}", stopwatch.ElapsedMilliseconds); Console.WriteLine("Branch count: {0}", _branchCount); Console.WriteLine("Leaf count: {0}", _leafCount); } private static void BrowseFromNode( EasyDAClient client, ServerDescriptor serverDescriptor, DANodeDescriptor parentNodeDescriptor) { Debug.Assert(client != null); Debug.Assert(serverDescriptor != null); Debug.Assert(parentNodeDescriptor != null); // Obtain all node elements under parentNodeDescriptor var browseParameters = new DABrowseParameters(); // no filtering whatsoever DANodeElementCollection nodeElementCollection = client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters); // Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for // it, here omitted for brevity. foreach (DANodeElement nodeElement in nodeElementCollection) { Debug.Assert(nodeElement != null); Console.WriteLine(nodeElement); // If the node is a branch, browse recursively into it. if (nodeElement.IsBranch) { _branchCount++; BrowseFromNode(client, serverDescriptor, nodeElement); } else { _leafCount++; } } } private static int _branchCount; private static int _leafCount; } }
# This example shows how to recursively browse the nodes in the OPC XML-DA address space. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python . # The QuickOPC package is needed. Install it using "pip install opclabs_quickopc". import opclabs_quickopc import timeit # Import .NET namespaces. from OpcLabs.EasyOpc import * from OpcLabs.EasyOpc.DataAccess import * from OpcLabs.EasyOpc.OperationModel import * def browseFromNode(client, serverDescriptor, parentNodeDescriptor): global branchCount global leafCount assert client is not None assert serverDescriptor is not None assert parentNodeDescriptor is not None # Obtain all node elements under parentNodeDescriptor. browseParameters = DABrowseParameters() # no filtering whatsoever nodeElementCollection = client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters) # BrowseNodes(...) may also throw OpcException; here it is handled by the caller. for nodeElement in nodeElementCollection: assert nodeElement is not None print(nodeElement) # If the node is a branch, browse recursively into it. if nodeElement.IsBranch: branchCount = branchCount + 1 browseFromNode(client, serverDescriptor, DANodeDescriptor(nodeElement)) else: leafCount = leafCount + 1 beginTime = timeit.default_timer() # Instantiate the client object. client = EasyDAClient() branchCount = 0 leafCount = 0 try: browseFromNode(client, ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'), DANodeDescriptor('')) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message) exit() endTime = timeit.default_timer() print() print('Browsing has taken (milliseconds): ',(endTime - beginTime)*1000) print('Branch count: ', branchCount); print('Leaf count: ', leafCount);
' This example shows how to recursively browse the nodes in the OPC XML-DA address space. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Imports OpcLabs.EasyOpc Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess.Xml Partial Friend Class BrowseNodes Shared Sub RecursiveXml() Dim stopwatch = New Stopwatch() stopwatch.Start() Dim client = New EasyDAClient() _branchCount = 0 _leafCount = 0 Try BrowseFromNode(client, "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try stopwatch.Stop() Console.WriteLine("Browsing has taken (milliseconds): {0}", stopwatch.ElapsedMilliseconds) Console.WriteLine("Branch count: {0}", _branchCount) Console.WriteLine("Leaf count: {0}", _leafCount) End Sub Private Shared Sub BrowseFromNode( _ client As EasyDAClient, serverDescriptor As ServerDescriptor, parentNodeDescriptor As DANodeDescriptor) Debug.Assert(client IsNot Nothing) Debug.Assert(serverDescriptor IsNot Nothing) Debug.Assert(parentNodeDescriptor IsNot Nothing) ' Obtain all node elements under parentNodeDescriptor Dim browseParameters = New DABrowseParameters() ' no filtering whatsoever Dim nodeElementCollection As DANodeElementCollection = client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters) ' Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for ' it, here omitted for brevity. For Each nodeElement As DANodeElement In nodeElementCollection Debug.Assert(nodeElement IsNot Nothing) Console.WriteLine(nodeElement) ' If the node is a branch, browse recursively into it. If nodeElement.IsBranch Then _branchCount += 1 BrowseFromNode(client, serverDescriptor, nodeElement) Else _leafCount += 1 End If Next nodeElement End Sub Private Shared _branchCount As Integer Private Shared _leafCount As Integer End Class End Namespace
// This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays // whether the node is a branch or a leaf. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . class procedure BrowseNodes.Main; var BrowseParameters: _DABrowseParameters; Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; Count: Cardinal; Element: OleVariant; ServerDescriptor: _ServerDescriptor; NodeDescriptor: _DANodeDescriptor; NodeElement: _DANodeElement; NodeElementEnumerator: IEnumVariant; NodeElements: _DANodeElementCollection; begin ServerDescriptor := CoServerDescriptor.Create; ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2'; NodeDescriptor := CoDANodeDescriptor.Create; NodeDescriptor.ItemId := 'Simulation'; BrowseParameters := CoDABrowseParameters.Create; // Instantiate the client object Client := CoEasyDAClient.Create; try NodeElements := Client.BrowseNodes( ServerDescriptor, NodeDescriptor, BrowseParameters); except on E: EOleException do begin WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message])); Exit; end; end; NodeElementEnumerator := NodeElements.GetEnumerator; while (NodeElementEnumerator.Next(1, Element, Count) = S_OK) do begin NodeElement := IUnknown(Element) as _DANodeElement; // WriteLn(NodeElement.Name, ': ', NodeElement.ItemId); WriteLn('BrowseElements("', NodeElement.Name, '"):'); WriteLn(' .IsBranch: ', NodeElement.IsBranch); WriteLn(' .IsLeaf: ', NodeElement.IsLeaf); end; end;
// This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays // whether the node is a branch or a leaf. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . $ServerDescriptor = new COM("OpcLabs.EasyOpc.ServerDescriptor"); $ServerDescriptor->ServerClass = "OPCLabs.KitServer.2"; $NodeDescriptor = new COM("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor"); $NodeDescriptor->ItemID = "Simulation"; $BrowseParameters = new COM("OpcLabs.EasyOpc.DataAccess.DABrowseParameters"); $Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient"); try { $NodeElements = $Client->BrowseNodes($ServerDescriptor, $NodeDescriptor, $BrowseParameters); } catch (com_exception $e) { printf("*** Failure: %s\n", $e->getMessage()); Exit(); } foreach ($NodeElements as $NodeElement) { printf("NodeElements(\"%s\"):\n", $NodeElement->Name); printf(" .IsBranch: %s\n", $NodeElement->IsBranch ? 'true' : 'false'); printf(" .IsLeaf: %s\n", $NodeElement->IsLeaf ? 'true' : 'false'); }
# This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays # whether the node is a branch or a leaf. # # The Python for Windows (pywin32) extensions package is needed. Install it using "pip install pypiwin32". # CAUTION: We now recommend using Python.NET package instead. Full set of examples with Python.NET is available! # # Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . import win32com.client from pywintypes import com_error serverDescriptor = win32com.client.Dispatch('OpcLabs.EasyOpc.ServerDescriptor') serverDescriptor.ServerClass = 'OPCLabs.KitServer.2' nodeDescriptor = win32com.client.Dispatch('OpcLabs.EasyOpc.DataAccess.DANodeDescriptor') nodeDescriptor.ItemID = 'Simulation' browseParameters = win32com.client.Dispatch('OpcLabs.EasyOpc.DataAccess.DABrowseParameters') # Instantiate the client object client = win32com.client.Dispatch('OpcLabs.EasyOpc.DataAccess.EasyDAClient') # Perform the operation try: nodeElements = client.BrowseNodes(serverDescriptor, nodeDescriptor, browseParameters) except com_error as e: print('*** Failure: ' + e.args[2][1] + ': ' + e.args[2][2]) exit() # Display results for nodeElement in nodeElements: print('NodeElements("' + nodeElement.Name + '"):') print(' .IsBranch:', nodeElement.IsBranch) print(' .IsLeaf:', nodeElement.IsLeaf) # Example output: # #NodeElements("Register_ArrayOfI1"): # .IsBranch: False # .IsLeaf: True #NodeElements("Register_ArrayOfI2"): # .IsBranch: False # .IsLeaf: True #NodeElements("Register_ArrayOfI4"): # .IsBranch: False # .IsLeaf: True #NodeElements("Staircase 0:2 (10 s)"): # .IsBranch: False # .IsLeaf: True #NodeElements("Constant_VARIANT"): # .IsBranch: False # .IsLeaf: True #...
// This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays // whether the node is a branch or a leaf. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . mle_outputtext.Text = "" // Instantiate the client object OLEObject client client = CREATE OLEObject client.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") // Prepare the arguments OLEObject serverDescriptor serverDescriptor = CREATE OLEObject serverDescriptor.ConnectToNewObject("OpcLabs.EasyOpc.ServerDescriptor") serverDescriptor.ServerClass = "OPCLabs.KitServer.2" OLEObject nodeDescriptor nodeDescriptor = CREATE OLEObject nodeDescriptor.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor") nodeDescriptor.ItemID = "Simulation" OLEObject browseParameters browseParameters = CREATE OLEObject browseParameters.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.DABrowseParameters") // Perform the operation OLEObject nodeElements TRY nodeElements = client.BrowseNodes(serverDescriptor, nodeDescriptor, browseParameters) CATCH (OLERuntimeError oleRuntimeError) mle_outputtext.Text = mle_outputtext.Text + "*** Failure: " + oleRuntimeError.Description + "~r~n" RETURN END TRY OLEObject nodeElementList nodeElementList = nodeElements.ToList() // Display results Int i FOR i = 0 TO nodeElementList.Count - 1 OLEObject nodeElement nodeElement = nodeElementList.Item[i] mle_outputtext.Text = mle_outputtext.Text + 'NodeElements("' + nodeElement.Name + '"):' + "~r~n" mle_outputtext.Text = mle_outputtext.Text + " nodeElement.IsBranch: " + String(nodeElement.IsBranch) + "~r~n" mle_outputtext.Text = mle_outputtext.Text + " nodeElement.IsLeaf: " + String(nodeElement.IsLeaf) + "~r~n" NEXT mle_outputtext.Text = mle_outputtext.Text + "~r~n" mle_outputtext.Text = mle_outputtext.Text + "Finished." + "~r~n"
REM This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays REM whether the node is a branch or a leaf. REM REM Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Private Sub BrowseNodes_Main_Command_Click() OutputText = "" Dim serverDescriptor As New serverDescriptor serverDescriptor.ServerClass = "OPCLabs.KitServer.2" Dim nodeDescriptor As New DANodeDescriptor nodeDescriptor.itemId = "Simulation" Dim browseParameters As New DABrowseParameters ' Instantiate the client object Dim client As New EasyDAClient On Error Resume Next Dim nodeElements As DANodeElementCollection Set nodeElements = client.BrowseNodes(serverDescriptor, nodeDescriptor, browseParameters) If Err.Number <> 0 Then OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf Exit Sub End If On Error GoTo 0 Dim nodeElement: For Each nodeElement In nodeElements OutputText = OutputText & "BrowseElements(""" & nodeElement.Name & """): " & nodeElement.itemId & vbCrLf OutputText = OutputText & " .IsBranch: " & nodeElement.IsBranch & vbCrLf OutputText = OutputText & " .IsLeaf: " & nodeElement.IsLeaf & vbCrLf Next End Sub
Rem This example shows how to obtain all nodes under the "Simulation" branch of the address space. For each node, it displays Rem whether the node is a branch or a leaf. Rem Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Option Explicit Dim ServerDescriptor: Set ServerDescriptor = CreateObject("OpcLabs.EasyOpc.ServerDescriptor") ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" Dim NodeDescriptor: Set NodeDescriptor = CreateObject("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor") NodeDescriptor.ItemID = "Simulation" Dim BrowseParameters: Set BrowseParameters = CreateObject("OpcLabs.EasyOpc.DataAccess.DABrowseParameters") Dim Client: Set Client= CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") On Error Resume Next Dim NodeElements: Set NodeElements = Client.BrowseNodes(ServerDescriptor, NodeDescriptor, BrowseParameters) If Err.Number <> 0 Then WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description WScript.Quit End If On Error Goto 0 Dim NodeElement: For Each NodeElement In NodeElements WScript.Echo "NodeElements(""" & NodeElement.Name & """):" With NodeElement WScript.Echo Space(4) & ".IsBranch: " & .IsBranch WScript.Echo Space(4) & ".IsLeaf: " & .IsLeaf End With Next
// This example shows how to recursively browse the nodes in the OPC XML-DA address space. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . type TBrowseNodes = class BranchCount: Integer; LeafCount: Integer; procedure BrowseFromNode( Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; ServerDescriptor: _ServerDescriptor; ParentNodeDescriptor: _DANodeDescriptor); end; procedure TBrowseNodes.BrowseFromNode( Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; ServerDescriptor: _ServerDescriptor; ParentNodeDescriptor: _DANodeDescriptor); var BrowseParameters: _DABrowseParameters; Count: Cardinal; Element: OleVariant; NodeElement: _DANodeElement; NodeElementEnumerator: IEnumVariant; NodeElements: _DANodeElementCollection; begin // Obtain all node elements under ParentNodeDescriptor BrowseParameters := CoDABrowseParameters.Create; // no filtering whatsover NodeElements := Client.BrowseNodes( ServerDescriptor, ParentNodeDescriptor, BrowseParameters); // Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for // it, here omitted for brevity. NodeElementEnumerator := NodeElements.GetEnumerator; while (NodeElementEnumerator.Next(1, Element, Count) = S_OK) do begin NodeElement := IUnknown(Element) as _DANodeElement; WriteLn(NodeElement.ToString); // If the node is a branch, browse recursively into it. if NodeElement.IsBranch then begin BranchCount := BranchCount + 1; BrowseFromNode(Client, ServerDescriptor, NodeElement.ToDANodeDescriptor); end else LeafCount := LeafCount + 1; end; end; class procedure BrowseNodes.RecursiveXml; var BeginTime: Cardinal; BrowseNodes: TBrowseNodes; Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; EndTime: Cardinal; ServerDescriptor: _ServerDescriptor; NodeDescriptor: _DANodeDescriptor; begin BrowseNodes := TBrowseNodes.Create; BrowseNodes.BranchCount := 0; BrowseNodes.LeafCount := 0; BeginTime := Ticks; ServerDescriptor := CoServerDescriptor.Create; ServerDescriptor.UrlString := 'http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'; NodeDescriptor := CoDANodeDescriptor.Create; NodeDescriptor.ItemId := ''; // Instantiate the client object Client := CoEasyDAClient.Create; try BrowseNodes.BrowseFromNode( Client, ServerDescriptor, NodeDescriptor); except on E: EOleException do begin WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message])); Exit; end; end; EndTime := Ticks; WriteLn; WriteLn('Browsing has taken (milliseconds): ', (endTime - beginTime) * 1000); WriteLn('Branch count: ', BrowseNodes.BranchCount); WriteLn('Leaf count: ', BrowseNodes.LeafCount); end;
// This example shows how to recursively browse the nodes in the OPC XML-DA address space. // // Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . $beginTime = microtime(true); $branchCount = 0; $leafCount = 0; $ServerDescriptor = new COM("OpcLabs.EasyOpc.ServerDescriptor"); $ServerDescriptor->UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"; $NodeDescriptor = new COM("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor"); $NodeDescriptor->ItemID = ""; // Instantiate the client object. $Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient"); try { BrowseFromNode($Client, $ServerDescriptor, $NodeDescriptor); } catch (com_exception $e) { printf("*** Failure: %s\n", $e->getMessage()); Exit(); } $endTime = microtime(true); printf("\n"); printf("Browsing has taken (milliseconds): : %f\n", ($endTime - $beginTime) * 1000); printf("Branch count: %d\n", $branchCount); printf("Leaf count: %d\n", $leafCount); function BrowseFromNode($Client, $ServerDescriptor, $ParentNodeDescriptor) : void { global $branchCount, $leafCount; // Obtain all node elements under ParentNodeDescriptor $BrowseParameters = new COM("OpcLabs.EasyOpc.DataAccess.DABrowseParameters"); // no filtering whatsoever $NodeElementCollection = $Client->BrowseNodes($ServerDescriptor, $ParentNodeDescriptor,$BrowseParameters); // Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for //it, here omitted for brevity. foreach ($NodeElementCollection as $NodeElement) { printf("%s\n", $NodeElement); // If the node is a branch, browse recursively into it. if ($NodeElement->IsBranch) { $branchCount = $branchCount + 1; BrowseFromNode($Client, $ServerDescriptor, $NodeElement->ToDANodeDescriptor()); } else { $leafCount = $leafCount + 1; } } }
Rem This example shows how to recursively browse the nodes in the OPC XML-DA address space. Rem Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . 'Public branchCount As Integer 'Public leafCount As Integer Private Sub BrowseNodes_RecursiveXml_Command_Click() OutputText = "" branchCount = 0 leafCount = 0 Dim beginTime: beginTime = Timer Dim serverDescriptor As New serverDescriptor serverDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx" Dim NodeDescriptor As New DANodeDescriptor NodeDescriptor.ItemId = "" ' Instantiate the client object Dim client As New EasyDAClient On Error Resume Next BrowseFromNode client, serverDescriptor, NodeDescriptor If Err.Number <> 0 Then OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf Exit Sub End If On Error GoTo 0 Dim endTime: endTime = Timer OutputText = OutputText & vbCrLf OutputText = OutputText & "Browsing has taken (milliseconds): " & (endTime - beginTime) * 1000 & vbCrLf OutputText = OutputText & "Branch count: " & branchCount & vbCrLf OutputText = OutputText & "Leaf count: " & leafCount & vbCrLf End Sub Public Sub BrowseFromNode(client, serverDescriptor, ParentNodeDescriptor) ' Obtain all node elements under ParentNodeDescriptor Dim BrowseParameters As New DABrowseParameters Dim NodeElementCollection As DANodeElementCollection Set NodeElementCollection = client.BrowseNodes(serverDescriptor, ParentNodeDescriptor, BrowseParameters) ' Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for ' it, here omitted for brevity. Dim NodeElement: For Each NodeElement In NodeElementCollection OutputText = OutputText & NodeElement & vbCrLf ' If the node is a branch, browse recursively into it. If NodeElement.IsBranch Then branchCount = branchCount + 1 BrowseFromNode client, serverDescriptor, NodeElement.ToDANodeDescriptor Else leafCount = leafCount + 1 End If Next End Sub
Rem This example shows how to recursively browse the nodes in the OPC XML-DA address space. Rem Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Option Explicit Dim beginTime: beginTime = Timer Dim branchCount: branchCount = 0 Dim leafCount: leafCount = 0 Dim ServerDescriptor: Set ServerDescriptor = CreateObject("OpcLabs.EasyOpc.ServerDescriptor") ServerDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx" Dim NodeDescriptor: Set NodeDescriptor = CreateObject("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor") NodeDescriptor.ItemID = "" Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") On Error Resume Next BrowseFromNode Client, ServerDescriptor, NodeDescriptor If Err.Number <> 0 Then WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description WScript.Quit End If On Error Goto 0 Dim endTime: endTime = Timer WScript.Echo "" WScript.Echo "Browsing has taken (milliseconds): " & (endTime - beginTime) * 1000 WScript.Echo "Branch count: " & branchCount WScript.Echo "Leaf count: " & leafCount Sub BrowseFromNode(Client, ServerDescriptor, ParentNodeDescriptor) ' Obtain all node elements under ParentNodeDescriptor Dim BrowseParameters: Set BrowseParameters = CreateObject("OpcLabs.EasyOpc.DataAccess.DABrowseParameters") Dim NodeElementCollection: Set NodeElementCollection = Client.BrowseNodes(serverDescriptor, parentNodeDescriptor, browseParameters) ' Remark: that BrowseNodes(...) may also throw OpcException; a production code should contain handling for ' it, here omitted for brevity. Dim NodeElement: For Each NodeElement In NodeElementCollection WScript.Echo NodeElement ' If the node is a branch, browse recursively into it. If NodeElement.IsBranch Then branchCount = branchCount + 1 BrowseFromNode Client, ServerDescriptor, NodeElement.ToDANodeDescriptor Else leafCount = leafCount + 1 End If Next End Sub
Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows
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