Concepts > QuickOPC Concepts > QuickOPC Development Models > Imperative Programming Model > Imperative Programming Model for OPC Data (Classic and UA) > Obtaining Information (OPC Data) > Reading from OPC Classic Items > Reading just the value (OPC Classic) |
Some applications need the actual data value for further processing (e.g. for computations that need be performed on the values); in case the value does not have the Good quality, the computation cannot proceed (an error).
// This example shows how to read and display value of a single item. // One of the shortest examples possible. // // 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.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class ReadItemValue { public static void Main1() { // Instantiate the client object. var client = new EasyDAClient(); Console.WriteLine("Reading item value..."); object value; try { value = client.ReadItemValue("", "OPCLabs.KitServer.2", "Demo.Ramp"); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } Console.WriteLine(value); } } }
# This example shows how to read and display value of a single item. # One of the shortest examples possible. # # 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.DataAccess using namespace OpcLabs.EasyOpc.OperationModel # 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 Write-Host "Reading item value..." try { $value = [IEasyDAClientExtension]::ReadItemValue($client, "", "OPCLabs.KitServer.2", "Demo.Ramp") } catch [OpcException] { Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)" return } Write-Host $value
' This example shows how to read and display value of a single item. ' One of the shortest examples possible. ' ' 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.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class ReadItemValue Public Shared Sub Main1() Dim client As New EasyDAClient() Console.WriteLine("Reading item...") Try Console.WriteLine(client.ReadItemValue("", "OPCLabs.KitServer.2", "Demo.Ramp")) 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 read value of a single item, and display it. // // 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. $Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient"); try { $value = $Client->ReadItemValue("", "OPCLabs.KitServer.2", "Simulation.Random"); } catch (com_exception $e) { printf("*** Failure: %s\n", $e->getMessage()); Exit(); } printf("value: %s\n", $value);
// This example shows how to read values of a single item, and display it. // // Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html . // 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. var Client = new ActiveXObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient"); var value = Client.ReadItemValue("", "OPCLabs.KitServer.2", "Simulation.Random"); WScript.Echo("value: " + value);
// This example shows how to read value of a single item, and display it. // // 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 ReadItemValue.Main; var Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; Value: OleVariant; begin // Instantiate the client object Client := CoEasyDAClient.Create; try Value := Client.ReadItemValue('', 'OPCLabs.KitServer.2', 'Simulation.Random'); except on E: EOleException do begin WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message])); Exit; end; end; // Display results WriteLn('Value: ', Value); end;
// This example shows how to read and display value of a single item. // One of the shortest examples possible. mle_outputtext.Text = "" // Instantiate the client object OLEObject client client = CREATE OLEObject client.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") // Obtain value of a node mle_outputtext.Text = mle_outputtext.Text + "Reading item value..." + "~r~n" Any value TRY value = client.ReadItemValue("", "OPCLabs.KitServer.2", "Demo.Ramp") CATCH (OLERuntimeError oleRuntimeError) mle_outputtext.Text = mle_outputtext.Text + "*** Failure: " + oleRuntimeError.Description + "~r~n" RETURN END TRY // Display results mle_outputtext.Text = mle_outputtext.Text + String(value) + "~r~n"
# This example shows how to read value of a single item, and display it. # # 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 # Instantiate the client object client = win32com.client.Dispatch('OpcLabs.EasyOpc.DataAccess.EasyDAClient') # Perform the operation try: value = client.ReadItemValue('', 'OPCLabs.KitServer.2', 'Demo.Single') except com_error as e: print('*** Failure: ' + e.args[2][1] + ': ' + e.args[2][2]) exit() # Display results print('value: ', value)
REM This example shows how to read value of a single item, and display it. 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 ReadItemValue_Main_Command_Click() OutputText = "" ' Instantiate the client object Dim client As New EasyDAClient On Error Resume Next Dim value value = client.ReadItemValue("", "OPCLabs.KitServer.2", "Simulation.Random") If Err.Number <> 0 Then OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf Exit Sub End If On Error GoTo 0 ' Display results OutputText = OutputText & "Value: " & value & vbCrLf End Sub
Rem This example shows how to read value of a single item, and display it. 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 Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") On Error Resume Next Dim value: value = Client.ReadItemValue("", "OPCLabs.KitServer.2", "Simulation.Random") If Err.Number <> 0 Then WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description WScript.Quit End If On Error Goto 0 WScript.Echo "value: " & value
# This example shows how to read value of a single item, and display it. # # 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() print('Reading item value...') try: value = IEasyDAClientExtension.ReadItemValue(client, '', 'OPCLabs.KitServer.2', 'Demo.Single') except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() # Display results print('value: ', value, sep='')
// This example shows how to read value of a single item, and display it, using CLSID instead of ProgID of the OPC Server. // // 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.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class ReadItemValue { public static void CLSID() { // Instantiate the client object. var client = new EasyDAClient(); Console.WriteLine("Reading item value..."); object value; try { value = client.ReadItemValue("", "{C8A12F17-1E03-401E-B53D-6C654DD576DA}", "Simulation.Random"); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } Console.WriteLine($"value: {value}"); } } }
' This example shows how to read value of a single item, and display it, using CLSID instead of ProgID of the OPC Server. ' ' 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.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class ReadItemValue Public Shared Sub CLSID() ' Instantiate the client object. Dim client As New EasyDAClient() Console.WriteLine("Reading item value...") Dim value As Object Try value = client.ReadItemValue("", "{C8A12F17-1E03-401E-B53D-6C654DD576DA}", "Simulation.Random") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try Console.WriteLine($"value: {value}") End Sub End Class End Namespace
Rem This example shows how to read value of a single item, and display it, using CLSID instead of ProgID of the OPC Server. 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 Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") On Error Resume Next Dim value: value = Client.ReadItemValue("", "{C8A12F17-1E03-401E-B53D-6C654DD576DA}", "Simulation.Random") If Err.Number <> 0 Then WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description WScript.Quit End If On Error Goto 0 WScript.Echo "value: " & value
# This example shows how to read value of a single item, and display it, using CLSID instead of ProgID of the OPC # Server. # # 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 * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object client = EasyDAClient() print('Reading item value...') try: value = IEasyDAClientExtension.ReadItemValue(client, '', '{C8A12F17-1E03-401E-B53D-6C654DD576DA}', 'Simulation.Random') except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() # Display results print('value: ', value, sep='')
// This example shows how to read and display value of a single item. // One of the shortest examples possible. // // 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.OperationModel; namespace DocExamples.DataAccess.Xml { partial class ReadItemValue { public static void Main1Xml() { // Instantiate the client object. var client = new EasyDAClient(); Console.WriteLine("Reading item value..."); object value; try { value = client.ReadItemValue("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Double"); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } Console.WriteLine(value); } } }
' This example shows how to read and display value of a single item. ' One of the shortest examples possible. ' ' 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.OperationModel Namespace DataAccess.Xml Partial Friend Class ReadItemValue Public Shared Sub Main1Xml() Dim client As New EasyDAClient() Console.WriteLine("Reading item value...") Dim value As Object Try value = client.ReadItemValue("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Double") Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try Console.WriteLine(value) End Sub End Class End Namespace
# This example shows how to read and display value of a single item. # One of the shortest examples possible. # # 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 * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object. client = EasyDAClient() print('Reading item value...') try: value = IEasyDAClientExtension.ReadItemValue(client, ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'), DAItemDescriptor('Dynamic/Analog Types/Double')) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() # Display results print('value: ', value, sep='')
// Shows how to read an OPC item that is of array type. // // 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.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class ReadItemValue { public static void Array() { // Instantiate the client object. var client = new EasyDAClient(); Console.WriteLine("Reading array value..."); int[] value; try { // UInt16 is returned as Int32, because UInt16 is not a CLS-compliant type (and is not supported in VB.NET). value = (int[])client.ReadItemValue("", "OPCLabs.KitServer.2", "Simulation.ReadValue_ArrayOfUI2"); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } if (!(value is null)) { Console.WriteLine(value[0]); Console.WriteLine(value[1]); Console.WriteLine(value[2]); } } } }
' Shows how to read an OPC item that is of array type. ' ' 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.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class ReadItemValue Public Shared Sub Array() Dim client As New EasyDAClient() Console.WriteLine("Reading array value...") Dim value As Int32() Try ' UInt16 is returned as Int32, because UInt16 is not a CLS-compliant type (and is not supported in VB.NET). value = CType(client.ReadItemValue("", "OPCLabs.KitServer.2", "Simulation.ReadValue_ArrayOfUI2"), Int32()) Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try If Not IsNothing(value) Then Console.WriteLine(value(0)) Console.WriteLine(value(1)) Console.WriteLine(value(2)) End If End Sub End Class End Namespace
# Shows how to read an OPC item that is of array type. # # 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 * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object client = EasyDAClient() print('Reading array value...') try: # UInt16 is returned as Int32, because UInt16 is not a CLS-compliant type (and is not supported in VB.NET). value = IEasyDAClientExtension.ReadItemValue(client, '', 'OPCLabs.KitServer.2', 'Simulation.ReadValue_ArrayOfUI2') except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() # Display results if value is not None: print(value[0]) print(value[1]) print(value[2])
// This example shows how to read a value of a single item from the device and display its value. // // 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.OperationModel; namespace DocExamples.DataAccess._EasyDAClient { partial class ReadItemValue { public static void DeviceSource() { // Instantiate the client object. var client = new EasyDAClient(); Console.WriteLine("Reading item value..."); object value; try { // DADataSource enumeration: // Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined). // The data source (memory, OPC cache or OPC device) selection is based on the desired value age and // current status of data received from the server. value = client.ReadItemValue("OPCLabs.KitServer.2", "Demo.Ramp", DADataSource.Device); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } Console.WriteLine(value); } } }
' This example shows how to read a value of a single item from the device and display its value. ' ' 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.OperationModel Namespace DataAccess._EasyDAClient Partial Friend Class ReadItemValue Public Shared Sub DeviceSource() ' Instantiate the client object. Dim client As New EasyDAClient() Console.WriteLine("Reading item value...") Dim value As Object Try ' DADataSource enumeration: ' Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined). ' The data source (memory, OPC cache or OPC device) selection is based on the desired value age and ' current status of data received from the server. value = client.ReadItemValue("OPCLabs.KitServer.2", "Demo.Ramp", DADataSource.Device) Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try Console.WriteLine(value) End Sub End Class End Namespace
# This example shows how to read a value of a single item from the device and display its value. # # 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 * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object client = EasyDAClient() print('Reading item value...') try: # DADataSource enumeration: # Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined). # The data source (memory, OPC cache or OPC device) selection is based on the desired value age and # current status of data received from the server. value = IEasyDAClientExtension.ReadItemValue(client, ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Demo.Single'), DAReadParameters(DADataSource.Device)) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() # Display results print('value: ', value, sep='')
// This example shows how to read a value of a single item from the device and display its value. // // 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.OperationModel; namespace DocExamples.DataAccess.Xml { partial class ReadItemValue { public static void DeviceSourceXml() { // Instantiate the client object. var client = new EasyDAClient(); Console.WriteLine("Reading item value..."); object value; try { // DADataSource enumeration: // Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined). // The data source (memory, OPC cache or OPC device) selection is based on the desired value age and // current status of data received from the server. value = client.ReadItemValue("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Double", DADataSource.Device); } catch (OpcException opcException) { Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message); return; } Console.WriteLine(value); } } }
' This example shows how to read a value of a single item from the device and display its value. ' ' 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.OperationModel Namespace DataAccess.Xml Partial Friend Class ReadItemValue Public Shared Sub DeviceSourceXml() ' Instantiate the client object. Dim client As New EasyDAClient() Console.WriteLine("Reading item value...") Dim value As Object Try ' DADataSource enumeration: ' Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined). ' The data source (memory, OPC cache or OPC device) selection is based on the desired value age and ' current status of data received from the server. value = client.ReadItemValue("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Double", DADataSource.Device) Catch opcException As OpcException Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message) Exit Sub End Try Console.WriteLine(value) End Sub End Class End Namespace
# This example shows how to read a value of a single item from the device and display its value. # # 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 * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object. client = EasyDAClient() print('Reading item value...') try: # DADataSource enumeration: # Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined). # The data source (memory, OPC cache or OPC device) selection is based on the desired value age and # current status of data received from the server. value = IEasyDAClientExtension.ReadItemValue(client, ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'), DAItemDescriptor('Dynamic/Analog Types/Double'), DAReadParameters(DADataSource.Device)) except OpcException as opcException: print('*** Failure: ' + opcException.GetBaseException().Message, sep='') exit() # Display results print('value: ', value, sep='')
For reading just the data values of multiple data values (with a test for Good quality) in an efficient manner, call the ReadMultipleItemValues method (instead of multiple ReadItemValue calls in a loop). You will receive back an array of ValueResult objects.
In QuickOPC.NET, you can pass in a ServerDescriptor object and an array of DAItemDescriptor objects, or an array of DAItemArguments objects, to the ReadMultipleItemValues method.
// This example shows how to read values of 4 items at once, and display them. // // 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 System.Diagnostics; using OpcLabs.BaseLib.OperationModel; using OpcLabs.EasyOpc.DataAccess; namespace DocExamples.DataAccess._EasyDAClient { class ReadMultipleItemValues { public static void Main1() { // Instantiate the client object. var client = new EasyDAClient(); ValueResult[] valueResults = client.ReadMultipleItemValues("OPCLabs.KitServer.2", new DAItemDescriptor[] { "Simulation.Random", "Trends.Ramp (1 min)", "Trends.Sine (1 min)", "Simulation.Register_I4" }); for (int i = 0; i < valueResults.Length; i++) { ValueResult valueResult = valueResults[i]; Debug.Assert(!(valueResult is null)); if (valueResult.Succeeded) Console.WriteLine($"valueResults[{i}].Value: {valueResult.Value}"); else Console.WriteLine($"valueResults[{i}] *** Failure: {valueResult.ErrorMessageBrief}"); } } // Example output: // //valueResults[0].Value: 0.00125125888851588 //valueResults[1].Value: 0.732510924339294 //valueResults[2].Value: -0.993968485238202 //valueResults[3].Value: 0 } }
# This example shows how to read values of 4 items at once, and display them. # # 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.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 $valueResults = [IEasyDAClientExtension]::ReadMultipleItemValues($client, "OPCLabs.KitServer.2", @( (New-Object DAItemDescriptor("Simulation.Random")), (New-Object DAItemDescriptor("Trends.Ramp (1 min)")), (New-Object DAItemDescriptor("Trends.Sine (1 min)")), (New-Object DAItemDescriptor("Simulation.Register_I4")) )) for ($i = 0; $i -lt $valueResults.Length; $i++) { $valueResult = $valueResults[$i] if ($valueResult.Succeeded) { Write-Host "valueResults($($i)).Value: $($valueResult.Value)" } else { Write-Host "valueResults($($i)) *** Failure: $($valueResult.ErrorMessageBrief)" } } # Example output: # #valueResults(0).Value: 0.00125125888851588 #valueResults(1).Value: 0.732510924339294 #valueResults(2).Value: -0.993968485238202 #valueResults(3).Value: 0
' This example shows how to read values of 4 items at once, and display them. ' ' 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.BaseLib.OperationModel Imports OpcLabs.EasyOpc.DataAccess Namespace DataAccess._EasyDAClient Partial Friend Class ReadMultipleItemValues Public Shared Sub Main1() ' Instantiate the client object. Dim client = New EasyDAClient() Dim valueResults() As ValueResult = client.ReadMultipleItemValues("OPCLabs.KitServer.2", New DAItemDescriptor() {"Simulation.Random", "Trends.Ramp (1 min)", "Trends.Sine (1 min)", "Simulation.Register_I4"}) For i = 0 To valueResults.Length - 1 Dim valueResult As ValueResult = valueResults(i) Debug.Assert(valueResult IsNot Nothing) If valueResult.Succeeded Then Console.WriteLine($"valueResults[{i}].Value: {valueResult.Value}") Else Console.WriteLine($"valueResults[{i}] *** Failure: {valueResult.ErrorMessageBrief}") End If Next i End Sub ' Example output: ' 'valueResults[0].Value: 0.00125125888851588 'valueResults[1].Value: 0.732510924339294 'valueResults[2].Value: -0.993968485238202 'valueResults[3].Value: 0 End Class End Namespace
// This example shows how to read values of 4 items at once, and display them. // // 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 ReadMultipleItemValues.Main; var Arguments: OleVariant; Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient; I: Cardinal; ReadItemArguments1: _DAReadItemArguments; ReadItemArguments2: _DAReadItemArguments; ReadItemArguments3: _DAReadItemArguments; ReadItemArguments4: _DAReadItemArguments; ValueResult: _ValueResult; Results: OleVariant; begin ReadItemArguments1 := CoDAReadItemArguments.Create; ReadItemArguments1.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2'; ReadItemArguments1.ItemDescriptor.ItemID := 'Simulation.Random'; ReadItemArguments2 := CoDAReadItemArguments.Create; ReadItemArguments2.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2'; ReadItemArguments2.ItemDescriptor.ItemID := 'Trends.Ramp (1 min)'; ReadItemArguments3 := CoDAReadItemArguments.Create; ReadItemArguments3.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2'; ReadItemArguments3.ItemDescriptor.ItemID := 'Trends.Sine (1 min)'; ReadItemArguments4 := CoDAReadItemArguments.Create; ReadItemArguments4.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2'; ReadItemArguments4.ItemDescriptor.ItemID := 'Simulation.Register_I4'; Arguments := VarArrayCreate([0, 3], varVariant); Arguments[0] := ReadItemArguments1; Arguments[1] := ReadItemArguments2; Arguments[2] := ReadItemArguments3; Arguments[3] := ReadItemArguments4; // Instantiate the client object Client := CoEasyDAClient.Create; TVarData(Results).VType := varArray or varVariant; TVarData(Results).VArray := PVarArray( Client.ReadMultipleItemValues(Arguments)); // Display results for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do begin ValueResult := IInterface(Results[I]) as _ValueResult; if ValueResult.Succeeded then WriteLn('results(', i, ').Value: ', ValueResult.Value) else WriteLn('results(', i, ') *** Failure: ', ValueResult.ErrorMessageBrief); end; VarClear(Results); VarClear(Arguments); end;
// This example shows how to read the values of 4 different items at once. mle_outputtext.Text = "" // Instantiate the client object OLEObject client client = CREATE OLEObject client.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") // Prepare arguments. OLEObject readItemArguments1 readItemArguments1 = CREATE OLEObject readItemArguments1.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") readItemArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" readItemArguments1.ItemDescriptor.ItemID = "Simulation.Random" OLEObject readItemArguments2 readItemArguments2 = CREATE OLEObject readItemArguments2.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") readItemArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" readItemArguments2.ItemDescriptor.ItemID = "Trends.Ramp (1 min)" OLEObject readItemArguments3 readItemArguments3 = CREATE OLEObject readItemArguments3.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") readItemArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" readItemArguments3.ItemDescriptor.ItemID = "Trends.Sine (1 min)" OLEObject readItemArguments4 readItemArguments4 = CREATE OLEObject readItemArguments4.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") readItemArguments4.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" readItemArguments4.ItemDescriptor.ItemID = "Simulation.Register_I4" OLEObject readItemArgumentsList readItemArgumentsList = CREATE OLEObject readItemArgumentsList.ConnectToNewObject("OpcLabs.BaseLib.Collections.ElasticVector") readItemArgumentsList.Add(readItemArguments1) readItemArgumentsList.Add(readItemArguments2) readItemArgumentsList.Add(readItemArguments3) readItemArgumentsList.Add(readItemArguments4) // Obtain values. OLEObject valueResultList valueResultList = client.ReadItemValueList(readItemArgumentsList) // Display results Int i FOR i = 0 TO valueResultList.Count - 1 OLEObject valueResult valueResult = valueResultList.Item[i] IF valueResult.Succeeded THEN mle_outputtext.Text = mle_outputtext.Text + "valueResult[" + String(i) + "].Value: " + String(valueResult.Value) + "~r~n" ELSE mle_outputtext.Text = mle_outputtext.Text + "valueResult[" + String(i) + "] *** Failure: " + valueResult.ErrorMessageBrief + "~r~n" END IF NEXT
REM This example shows how to read values of 4 items at once, and display them. 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 ReadMultipleItemValues_Main_Command_Click() OutputText = "" Dim readArguments1 As New DAReadItemArguments readArguments1.serverDescriptor.ServerClass = "OPCLabs.KitServer.2" readArguments1.ItemDescriptor.itemId = "Simulation.Random" Dim readArguments2 As New DAReadItemArguments readArguments2.serverDescriptor.ServerClass = "OPCLabs.KitServer.2" readArguments2.ItemDescriptor.itemId = "Trends.Ramp (1 min)" Dim readArguments3 As New DAReadItemArguments readArguments3.serverDescriptor.ServerClass = "OPCLabs.KitServer.2" readArguments3.ItemDescriptor.itemId = "Trends.Sine (1 min)" Dim readArguments4 As New DAReadItemArguments readArguments4.serverDescriptor.ServerClass = "OPCLabs.KitServer.2" readArguments4.ItemDescriptor.itemId = "Simulation.Register_I4" Dim arguments(3) As Variant Set arguments(0) = readArguments1 Set arguments(1) = readArguments2 Set arguments(2) = readArguments3 Set arguments(3) = readArguments4 ' Instantiate the client object Dim client As New EasyDAClient Dim results() As Variant results = client.ReadMultipleItemValues(arguments) ' Display results Dim i: For i = LBound(results) To UBound(results) Dim valueResult As valueResult: Set valueResult = results(i) If valueResult.Succeeded Then OutputText = OutputText & "results(" & i & ").Value: " & valueResult.value & vbCrLf Else OutputText = OutputText & "results(" & i & ") *** Failure: " & valueResult.ErrorMessageBrief & vbCrLf End If Next End Sub
Rem This example shows how to read values of 4 items at once, and display them. 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 ReadItemArguments1: Set ReadItemArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") ReadItemArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" ReadItemArguments1.ItemDescriptor.ItemID = "Simulation.Random" Dim ReadItemArguments2: Set ReadItemArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") ReadItemArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" ReadItemArguments2.ItemDescriptor.ItemID = "Trends.Ramp (1 min)" Dim ReadItemArguments3: Set ReadItemArguments3 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") ReadItemArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" ReadItemArguments3.ItemDescriptor.ItemID = "Trends.Sine (1 min)" Dim ReadItemArguments4: Set ReadItemArguments4 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments") ReadItemArguments4.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2" ReadItemArguments4.ItemDescriptor.ItemID = "Simulation.Register_I4" Dim arguments(3) Set arguments(0) = ReadItemArguments1 Set arguments(1) = ReadItemArguments2 Set arguments(2) = ReadItemArguments3 Set arguments(3) = ReadItemArguments4 Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient") Dim results: results = Client.ReadMultipleItemValues(arguments) Dim i: For i = LBound(results) To UBound(results) Dim ValueResult: Set ValueResult = results(i) If ValueResult.Succeeded Then WScript.Echo "results(" & i & ").Value: " & ValueResult.Value Else WScript.Echo "results(" & i & ") *** Failure: " & ValueResult.ErrorMessageBrief End If Next
# This example shows how to read values of 4 items at once, and display them. # # 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 * from OpcLabs.EasyOpc.DataAccess.OperationModel import * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object. client = EasyDAClient() # valueResultArray = IEasyDAClientExtension.ReadMultipleItemValues(client, [ DAReadItemArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Simulation.Random')), DAReadItemArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Trends.Ramp (1 min)')), DAReadItemArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Trends.Sine (1 min)')), DAReadItemArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Simulation.Register_I4')), ]) for i, valueResult in enumerate(valueResultArray): assert valueResult is not None if valueResult.Succeeded: print('valueResultArray[', i, '].Value: ', valueResult.Value, sep='') else: print('valueResultArray[', i, '] *** Failure: ', valueResult.ErrorMessageBrief, sep='')
// This example shows how to read values of 4 items at once, and display them. // // 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 System.Diagnostics; using OpcLabs.BaseLib.OperationModel; using OpcLabs.EasyOpc.DataAccess; namespace DocExamples.DataAccess.Xml { class ReadMultipleItemValues { public static void Main1Xml() { // Instantiate the client object. var client = new EasyDAClient(); ValueResult[] valueResults = client.ReadMultipleItemValues("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", new DAItemDescriptor[] { "Dynamic/Analog Types/Double", "Dynamic/Analog Types/Double[]", "Dynamic/Analog Types/Int", "Static/Analog Types/Int" }); for (int i = 0; i < valueResults.Length; i++) { ValueResult valueResult = valueResults[i]; Debug.Assert(!(valueResult is null)); if (valueResult.Succeeded) Console.WriteLine($"valueResults[{i}].Value: {valueResult.Value}"); else Console.WriteLine($"valueResults[{i}] *** Failure: {valueResult.ErrorMessageBrief}"); } } // Example output: // //valueResults[0].Value: 50 //valueResults[1].Value: System.Double[] //valueResults[2].Value: 100 //valueResults[3].Value: 12345 } }
' This example shows how to read values of 4 items at once, and display them. ' ' 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.BaseLib.OperationModel Imports OpcLabs.EasyOpc.DataAccess Namespace DataAccess.Xml Partial Friend Class ReadMultipleItemValues Public Shared Sub Main1Xml() ' Instantiate the client object. Dim client = New EasyDAClient() Dim valueResults() As ValueResult = client.ReadMultipleItemValues("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", New DAItemDescriptor() {"Dynamic/Analog Types/Double", "Dynamic/Analog Types/Double[]", "Dynamic/Analog Types/Int", "Static/Analog Types/Int"}) For i = 0 To valueResults.Length - 1 Dim valueResult As ValueResult = valueResults(i) Debug.Assert(valueResult IsNot Nothing) If valueResult.Succeeded Then Console.WriteLine($"valueResults[{i}].Value: {valueResult.Value}") Else Console.WriteLine($"valueResults[{i}] *** Failure: {valueResult.ErrorMessageBrief}") End If Next i End Sub ' Example output: ' 'valueResults[0].Value: 50 'valueResults[1].Value System.Double[] 'valueResults[2].Value: 100 'valueResults[3].Value: 12345 End Class End Namespace
# This example shows how to read values of 4 items at once, and display them. # # 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 * from OpcLabs.EasyOpc.DataAccess.OperationModel import * from OpcLabs.EasyOpc.OperationModel import * # Instantiate the client object. client = EasyDAClient() valueResults = IEasyDAClientExtension.ReadMultipleItemValues(client, ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'), [ DAItemDescriptor('Dynamic/Analog Types/Double'), DAItemDescriptor('Dynamic/Analog Types/Double[]'), DAItemDescriptor('Dynamic/Analog Types/Int'), DAItemDescriptor('Static/Analog Types/Int') ]) for i, valueResult in enumerate(valueResults): assert valueResult is not None if valueResult.Succeeded: print('valueResults[', i, '].Value: ', valueResult.Value, sep='') else: print('valueResults[', i, '] *** Failure: ', valueResult.ErrorMessageBrief, sep='') # Example output: # #valueResults[0].Value: 0.00125125888851588 #valueResults[1].Value: System.Double[] #valueResults[2].Value: -0.993968485238202 #valueResults[3].Value: 0
It is possible to specify read parameters, such as the value age, or that the read should be performed from the cache, or directly from the device. For more information, see Reading from OPC Classic Items.
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