Examples - OPC XML-DA - Read multiple items

// This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps 
// and qualities.

using System;
using System.Diagnostics;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;

namespace DocExamples.DataAccess.Xml
{
    class ReadMultipleItems
    {
        public static void Main1Xml()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            DAVtqResult[] vtqResults = client.ReadMultipleItems(
                new ServerDescriptor { UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx" },
                new DAItemDescriptor[]
                    {
                        "Dynamic/Analog Types/Double", 
                        "Dynamic/Analog Types/Double[]", 
                        "Dynamic/Analog Types/Int", 
                        "SomeUnknownItem"
                    });

            for (int i = 0; i < vtqResults.Length; i++)
            {
                Debug.Assert(vtqResults[i] != null);

                if (!(vtqResults[i].Exception is null))
                {
                    Console.WriteLine($"vtqResults[{i}] *** Failure: {vtqResults[i].ErrorMessageBrief}");
                    continue;
                }
                Console.WriteLine($"vtqResults[{i}].Vtq: {vtqResults[i].Vtq}");
            }
        }
    }
}

# This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps 
# and qualities.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc
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

$serverDescriptor = New-Object ServerDescriptor -Property @{
    UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
}

$vtqResults = [IEasyDAClientExtension]::ReadMultipleItems($client, 
    $serverDescriptor, 
    @(
        (New-Object DAItemDescriptor("Dynamic/Analog Types/Double")),
        (New-Object DAItemDescriptor("Dynamic/Analog Types/Double[]")),
        (New-Object DAItemDescriptor("Dynamic/Analog Types/Int")),
        (New-Object DAItemDescriptor("SomeUnknownItem"))
        ))

for ($i = 0; $i -lt $vtqResults.Length; $i++) {
    $vtqResult = $vtqResults[$i]
    if ($vtqResult.Succeeded) {
        Write-Host "vtqResults[$($i)].Vtq: $($vtqResult.Vtq)"
    }
    else {
        Write-Host "vtqResults[$($i)] *** Failure: $($vtqResult.ErrorMessageBrief)"
    }
}

# This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps
# and qualities.

# 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()

#
vtqResultArray = IEasyDAClientExtension.ReadMultipleItems(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('SomeUnknownItem')
    ])

for i, vtqResult in enumerate(vtqResultArray):
    assert vtqResult is not None
    if vtqResult.Succeeded:
        print('vtqResultArray[', i, '].Vtq: ', vtqResult.Vtq, sep='')
    else:
        print('vtqResultArray[', i, '] *** Failure: ', vtqResult.ErrorMessageBrief, sep='')

print()
print('Finished.')

' This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps 
' and qualities.

Imports OpcLabs.EasyOpc
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.OperationModel

Namespace DataAccess.Xml
    Partial Friend Class ReadMultipleItems
        Public Shared Sub Main1Xml()
            Dim client = New EasyDAClient()

            Dim vtqResults() As DAVtqResult = client.ReadMultipleItems(
                    New ServerDescriptor() With {.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"},
                    New DAItemDescriptor() _
                    { _
                        "Dynamic/Analog Types/Double",
                        "Dynamic/Analog Types/Double[]",
                        "Dynamic/Analog Types/Int",
                        "SomeUnknownItem"
                    })

            For i = 0 To vtqResults.Length - 1
                Debug.Assert(vtqResults(i) IsNot Nothing)

                If vtqResults(i).Exception IsNot Nothing Then
                    Console.WriteLine("vtqResult[{0}] *** Failure: {1}", i, vtqResults(i).ErrorMessageBrief)
                    Continue For
                End If
                Console.WriteLine("vtqResult[{0}].Vtq: {1}", i, vtqResults(i).Vtq)
            Next i
        End Sub
    End Class
End Namespace

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

Conceptual

Examples - OPC Data Access

Examples - OPC Unified Architecture