Concepts > OPC Data Client Concepts > OPC Data Client Development Models > Imperative Programming Model > Imperative Programming Model for OPC Data (Classic and UA) > Browsing for Information (OPC Data) > Browsing for OPC Classic Properties |
Each OPC item has typically associated a set of OPC properties with it. OPC properties contain additional information related to the item. The OPC specifications define a set of common properties; however, each OPC server is free to implement some more, vendor-specific properties as well.
If you want to retrieve a list of all properties available on a given OPC item, call the BrowseProperties method, passing it the ItemID you are interested in. You will receive back a DAPropertyElementCollection object. Each DAPropertyElement contains information about one OPC property, such as its (numeric) PropertyId, data type, or a readable description. The PropertyId can be later used as an argument in calling methods such as GetPropertyValue.
You can use DAPropertyId.GetName and GetPropertyType methods to obtain the string identifier of the property, or its type. With OPC XML, properties are identified by a XML qualified name, and you will find it in the DAPropertyElement.QualifiedName property.
Constants for specific (well-known) OPC properties are contained in the DAPropertyIds enumeration.
// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . // OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp . // Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own // a commercial license in order to use Online Forums, and we reply to every post. using System; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { class BrowseProperties { public static void Main1() { // Instantiate the client object. var client = new EasyDAClient(); DAPropertyElementCollection propertyElements; try { propertyElements = client.BrowseProperties("OPCLabs.KitServer.2", "Simulation.Random"); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } foreach (DAPropertyElement propertyElement in propertyElements) Console.WriteLine($"PropertyElements(\"{propertyElement.PropertyId.NumericalValue}\").Description: {propertyElement.Description}"); } // Example output: // //PropertyElements("15008").Description: Visible //PropertyElements("5").Description: Item Access Rights //PropertyElements("2").Description: Item Value //PropertyElements("7").Description: Item EU Type //PropertyElements("15001").Description: Item Name //PropertyElements("4").Description: Item Timestamp //PropertyElements("1").Description: Item Canonical Data Type //PropertyElements("103").Description: Low EU //PropertyElements("15009").Description: Addable //PropertyElements("6").Description: Server Scan Rate //PropertyElements("15000").Description: Item ID //PropertyElements("3").Description: Item Quality } }
# This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. # # Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . # OPC client and subscriber examples in PowerShell on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PowerShell . # Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own # a commercial license in order to use Online Forums, and we reply to every post. #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 { $propertyElements = $client.BrowseProperties("OPCLabs.KitServer.2", "Simulation.Random") } catch [OpcException] { Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)" return } Foreach ($propertyElement in $propertyElements) { Write-Host "PropertyElements(`"$($propertyElement.PropertyId.NumericalValue)`").Description: $($propertyElement.Description)" } # Example output: # #PropertyElements("15008").Description: Visible #PropertyElements("5").Description: Item Access Rights #PropertyElements("2").Description: Item Value #PropertyElements("7").Description: Item EU Type #PropertyElements("15001").Description: Item Name #PropertyElements("4").Description: Item Timestamp #PropertyElements("1").Description: Item Canonical Data Type #PropertyElements("103").Description: Low EU #PropertyElements("15009").Description: Addable #PropertyElements("6").Description: Server Scan Rate #PropertyElements("15000").Description: Item ID #PropertyElements("3").Description: Item Quality
' This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . ' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET . ' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own ' a commercial license in order to use Online Forums, and we reply to every post. Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class BrowseProperties Shared Sub Main1() Dim client = New EasyDAClient() Dim propertyElements As DAPropertyElementCollection Try propertyElements = client.BrowseProperties("OPCLabs.KitServer.2", "Simulation.Random") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try For Each propertyElement In propertyElements Console.WriteLine($"PropertyElements(""{propertyElement.PropertyId.NumericalValue}"").Description: {propertyElement.Description}") Next propertyElement End Sub ' Example output ' 'PropertyElements("15008").Description: Visible 'PropertyElements("5").Description: Item Access Rights 'PropertyElements("2").Description: Item Value 'PropertyElements("7").Description: Item EU Type 'PropertyElements("15001").Description: Item Name 'PropertyElements("4").Description: Item Timestamp 'PropertyElements("1").Description: Item Canonical Data Type 'PropertyElements("103").Description: Low EU 'PropertyElements("15009").Description: Addable 'PropertyElements("6").Description: Server Scan Rate 'PropertyElements("15000").Description: Item ID 'PropertyElements("3").Description: Item Quality End Class End Namespace
// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . // OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP . // Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own // a commercial license in order to use Online Forums, and we reply to every post. class procedure BrowseProperties.Main; var Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; Count: Cardinal; Element: OleVariant; ServerDescriptor: _ServerDescriptor; NodeDescriptor: _DANodeDescriptor; PropertyElement: _DAPropertyElement; PropertyElementEnumerator: IEnumVariant; PropertyElements: _DAPropertyElementCollection; begin ServerDescriptor := CoServerDescriptor.Create; ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2'; NodeDescriptor := CoDANodeDescriptor.Create; NodeDescriptor.ItemId := 'Simulation.Random'; // Instantiate the client object Client := CoEasyDAClient.Create; try PropertyElements := Client.BrowseProperties( ServerDescriptor, NodeDescriptor); except on E: EOleException do begin WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message])); Exit; end; end; PropertyElementEnumerator := PropertyElements.GetEnumerator; while (PropertyElementEnumerator.Next(1, Element, Count) = S_OK) do begin PropertyElement := IUnknown(Element) as _DAPropertyElement; WriteLn('PropertyElements("', PropertyElement.PropertyId.NumericalValue, '").Description: ', PropertyElement.Description); end; end;
// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . // OPC client and subscriber examples in PHP on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PHP . // Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own // a commercial license in order to use Online Forums, and we reply to every post. $ServerDescriptor = new COM("OpcLabs.EasyOpc.ServerDescriptor"); $ServerDescriptor->ServerClass = "OPCLabs.KitServer.2"; $NodeDescriptor = new COM("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor"); $NodeDescriptor->ItemID = "Simulation.Random"; $Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient"); try { $PropertyElements = $Client->BrowseProperties($ServerDescriptor, $NodeDescriptor); } catch (com_exception $e) { printf("*** Failure: %s\n", $e->getMessage()); Exit(); } foreach ($PropertyElements as $PropertyElement) { printf("PropertyElements(\"s\").Descriptions\n", $PropertyElement->PropertyID->NumericalValue, $PropertyElement->Description); }
REM This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. REM REM Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . REM OPC client and subscriber examples in Visual Basic on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VB . REM Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own REM a commercial license in order to use Online Forums, and we reply to every post. Private Sub BrowseProperties_Main_Command_Click() OutputText = "" Dim serverDescriptor As New serverDescriptor serverDescriptor.ServerClass = "OPCLabs.KitServer.2" Dim nodeDescriptor As New DANodeDescriptor nodeDescriptor.itemId = "Simulation.Random" ' Instantiate the client object Dim client As New EasyDAClient On Error Resume Next Dim propertyElements As DAPropertyElementCollection Set propertyElements = client.BrowseProperties(serverDescriptor, nodeDescriptor) If Err.Number <> 0 Then OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf Exit Sub End If On Error GoTo 0 Dim propertyElement: For Each propertyElement In propertyElements OutputText = OutputText & "propertyElements(""" & propertyElement.propertyId.NumericalValue & """).Description: " & propertyElement.Description & vbCrLf Next End Sub
Rem This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description. Rem Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript . Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own Rem a commercial license in order to use Online Forums, and we reply to every post. 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.Random" Dim EasyDAClient: Set EasyDAClient = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") On Error Resume Next Dim PropertyElements: Set PropertyElements = EasyDAClient.BrowseProperties(ServerDescriptor, NodeDescriptor) If Err.Number <> 0 Then WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description WScript.Quit End If On Error Goto 0 Dim PropertyElement: For Each PropertyElement In PropertyElements WScript.Echo "PropertyElements(""" & PropertyElement.PropertyID.NumericalValue & """).Description: " & PropertyElement.Description Next
# This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and # description. # # 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 . # Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own # a commercial license in order to use Online Forums, and we reply to every post. # 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: propertyElements = IEasyDAClientExtension.BrowseProperties(client, '', 'OPCLabs.KitServer.2', 'Simulation.Random') except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message) exit() # Display results. for propertyElement in propertyElements: print('PropertyElements[', propertyElement.PropertyId.NumericalValue, '].Description: ', propertyElement.Description, sep='')
// This example shows how to enumerate all properties of an OPC XML-DA item. For each property, it displays its Id and description. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . // OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp . // Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own // a commercial license in order to use Online Forums, and we reply to every post. using System; using OpcLabs.EasyOpc.DataAccess; using OpcLabs.EasyOpc.DataAccess.AddressSpace; using OpcLabs.EasyOpc.OperationModel; namespace DocExamples.DataAccess.Xml { class BrowseProperties { public static void Main1Xml() { // Instantiate the client object. var client = new EasyDAClient(); DAPropertyElementCollection propertyElements; try { propertyElements = client.BrowseProperties("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Int"); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } foreach (DAPropertyElement propertyElement in propertyElements) Console.WriteLine($"PropertyElements(\"{propertyElement.PropertyId.NumericalValue}\").Description: {propertyElement.Description}"); } // Example output: // //PropertyElements("1").Description: Item Canonical DataType //PropertyElements("2").Description: Item Value //PropertyElements("3").Description: Item Quality //PropertyElements("4").Description: Item Timestamp //PropertyElements("5").Description: Item Access Rights //PropertyElements("6").Description: Server Scan Rate //PropertyElements("7").Description: Item EU Type //PropertyElements("8").Description: Item EU Info //PropertyElements("102").Description: High EU //PropertyElements("103").Description: Low EU } }
' This example shows how to enumerate all properties of an OPC XML-DA item. For each property, it displays its Id and description. ' ' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . ' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET . ' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own ' a commercial license in order to use Online Forums, and we reply to every post. Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.AddressSpace Imports OpcLabs.EasyOpc.OperationModel Namespace DataAccess.Xml Partial Friend Class BrowseProperties Shared Sub Main1Xml() Dim client = New EasyDAClient() Dim propertyElements As DAPropertyElementCollection Try propertyElements = client.BrowseProperties("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Int") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try For Each propertyElement In propertyElements Console.WriteLine($"PropertyElements(""{propertyElement.PropertyId.NumericalValue}"").Description: {propertyElement.Description}") Next propertyElement End Sub ' Example output ' 'PropertyElements("1").Description: Item Canonical DataType 'PropertyElements("2").Description: Item Value 'PropertyElements("3").Description: Item Quality 'PropertyElements("4").Description: Item Timestamp 'PropertyElements("5").Description: Item Access Rights 'PropertyElements("6").Description: Server Scan Rate 'PropertyElements("7").Description: Item EU Type 'PropertyElements("8").Description: Item EU Info 'PropertyElements("102").Description: High EU 'PropertyElements("103").Description: Low EU End Class End Namespace
# This example shows how to enumerate all properties of an OPC XML-DA item. For each property, it displays its Id and description. # # 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 . # Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own # a commercial license in order to use Online Forums, and we reply to every post. # 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 * # Instantiate the client object. client = EasyDAClient() try: propertyElements = client.BrowseProperties(ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'), DANodeDescriptor('Dynamic/Analog Types/Int')) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() for propertyElement in propertyElements: print('PropertyElements("', propertyElement.PropertyId.NumericalValue, '").Description: ', propertyElement.Description, sep='') # Example output: # #PropertyElements("1").Description: Item Canonical DataType #PropertyElements("2").Description: Item Value #PropertyElements("3").Description: Item Quality #PropertyElements("4").Description: Item Timestamp #PropertyElements("5").Description: Item Access Rights #PropertyElements("6").Description: Server Scan Rate #PropertyElements("7").Description: Item EU Type #PropertyElements("8").Description: Item EU Info #PropertyElements("102").Description: High EU #PropertyElements("103").Description: Low EU
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