Examples - OPC XML-DA - Read a single item

.NET

C#
VB.NET

// This example shows how to read a single item, and display its value, timestamp and quality.
//
// 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 ReadItem
    {
        public static void Main1Xml()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            DAVtq vtq;
            try
            {
                vtq = client.ReadItem("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Dynamic/Analog Types/Int");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            Console.WriteLine("Vtq: {0}", vtq);
        }
    }
}

' This example shows how to read a single item, and display its value, timestamp and quality.
'
' 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 ReadItem
        Public Shared Sub Main1Xml()
            Dim client = New EasyDAClient()

            Dim vtq As DAVtq
            Try
                vtq = client.ReadItem("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

            Console.WriteLine("Vtq: {0}", vtq)
        End Sub
    End Class
End Namespace

Python

Python (.NET)

# This example shows how to read a single item, and display its value, timestamp and quality.
#
# 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()

# Perform the operation.
try:
    vtq = IEasyDAClientExtension.ReadItem(client, ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'), DAItemDescriptor('Dynamic/Analog Types/Int'))
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message, sep='')
    exit()

# Display results.
print('Vtq: ', vtq, sep='')

QuickOPC supports OPC XML-DA also on Linux and macOS.

.NET

Python

Examples - Client OPC Data Access

Concepts

Examples - Client OPC Unified Architecture