Examples - OPC XML-DA - Read multiple items

.NET

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

namespace DocExamples.DataAccess.Xml
{
    partial 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.
#
# 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
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.
#
# 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.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='')

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

COM

// This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps
// and qualities.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure ReadMultipleItems.MainXml;
var
  Arguments: OleVariant;
  Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient;
  I: Cardinal;
  ReadItemArguments1: _DAReadItemArguments;
  ReadItemArguments2: _DAReadItemArguments;
  ReadItemArguments3: _DAReadItemArguments;
  ReadItemArguments4: _DAReadItemArguments;
  VtqResult: _DAVtqResult;
  Results: OleVariant;
begin
  ReadItemArguments1 := CoDAReadItemArguments.Create;
  ReadItemArguments1.ServerDescriptor.UrlString := 'http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx';
  ReadItemArguments1.ItemDescriptor.ItemID := 'Dynamic/Analog Types/Double';

  ReadItemArguments2 := CoDAReadItemArguments.Create;
  ReadItemArguments2.ServerDescriptor.UrlString := 'http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx';
  ReadItemArguments2.ItemDescriptor.ItemID := 'Dynamic/Analog Types/Double[]';

  ReadItemArguments3 := CoDAReadItemArguments.Create;
  ReadItemArguments3.ServerDescriptor.UrlString := 'http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx';
  ReadItemArguments3.ItemDescriptor.ItemID := 'Dynamic/Analog Types/Int';

  ReadItemArguments4 := CoDAReadItemArguments.Create;
  ReadItemArguments4.ServerDescriptor.UrlString := 'http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx';
  ReadItemArguments4.ItemDescriptor.ItemID := 'SomeUnknownItem';

  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.ReadMultipleItems(Arguments));

  // Display results
  for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do
  begin
      VtqResult := IInterface(Results[I]) as _DAVtqResult;
      if VtqResult.Exception <> nil then
      begin
        WriteLn('results[', i, '] *** Failure: ', VtqResult.ErrorMessageBrief);
        Continue;
      end;
      WriteLn('results[', i, '].Vtq.ToString(): ', VtqResult.Vtq.ToString);
  end;

  VarClear(Results);
  VarClear(Arguments);
end;

// This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps 
// and qualities.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

$ReadItemArguments1 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments");
$ReadItemArguments1->ServerDescriptor->UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx";
$ReadItemArguments1->ItemDescriptor->ItemID = "Dynamic/Analog Types/Double";

$ReadItemArguments2 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments");
$ReadItemArguments2->ServerDescriptor->UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx";
$ReadItemArguments2->ItemDescriptor->ItemID = "Dynamic/Analog Types/Double[]";

$ReadItemArguments3 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments");
$ReadItemArguments3->ServerDescriptor->UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx";
$ReadItemArguments3->ItemDescriptor->ItemID = "Dynamic/Analog Types/Int";

$ReadItemArguments4 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments");
$ReadItemArguments4->ServerDescriptor->UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx";
$ReadItemArguments4->ItemDescriptor->ItemID = "SomeUnknownItem";

$arguments[0] = $ReadItemArguments1;
$arguments[1] = $ReadItemArguments2;
$arguments[2] = $ReadItemArguments3;
$arguments[3] = $ReadItemArguments4;

$Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient");

$results = $Client->ReadMultipleItems($arguments);

for ($i = 0; $i < count($results); $i++)
{
    $VtqResult = $results[$i];
    if ($VtqResult->Succeeded)
        printf("results[d].Vtq.ToString()s\n", $i, $VtqResult->Vtq->ToString);
    else
        printf("results[d]: *** Failures\n", $i, $VtqResult->ErrorMessageBrief);
}

Rem This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps
Rem and qualities.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Private Sub ReadMultipleItems_MainXml_Command_Click()
    OutputText = ""
    
    Dim readArguments1 As New DAReadItemArguments
    readArguments1.serverDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
    readArguments1.ItemDescriptor.ItemId = "Dynamic/Analog Types/Double"
    
    Dim readArguments2 As New DAReadItemArguments
    readArguments2.serverDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
    readArguments2.ItemDescriptor.ItemId = "Dynamic/Analog Types/Double[]"
    
    Dim readArguments3 As New DAReadItemArguments
    readArguments3.serverDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
    readArguments3.ItemDescriptor.ItemId = "Dynamic/Analog Types/Int"
    
    Dim readArguments4 As New DAReadItemArguments
    readArguments4.serverDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
    readArguments4.ItemDescriptor.ItemId = "SomeUnknownItem"
    
    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 vtqResults() As Variant
    vtqResults = client.ReadMultipleItems(arguments)

    ' Display results
    Dim i: For i = LBound(vtqResults) To UBound(vtqResults)
        Dim vtqResult As DAVtqResult: Set vtqResult = vtqResults(i)
        If Not (vtqResult.Exception Is Nothing) Then
            OutputText = OutputText & "results(" & i & ") *** Failure: " & vtqResult.ErrorMessageBrief & vbCrLf
        Else
        OutputText = OutputText & "results(" & i & ").Vtq.ToString(): " & vtqResult.vtq & vbCrLf
        End If
    Next
End Sub

Rem This example shows how to read 4 items from an OPC XML-DA server at once, and display their values, timestamps
Rem and qualities.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

Dim ReadItemArguments1: Set ReadItemArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments1.ServerDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
ReadItemArguments1.ItemDescriptor.ItemID = "Dynamic/Analog Types/Double"

Dim ReadItemArguments2: Set ReadItemArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments2.ServerDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
ReadItemArguments2.ItemDescriptor.ItemID = "Dynamic/Analog Types/Double[]"

Dim ReadItemArguments3: Set ReadItemArguments3 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments3.ServerDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
ReadItemArguments3.ItemDescriptor.ItemID = "Dynamic/Analog Types/Int"

Dim ReadItemArguments4: Set ReadItemArguments4 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments4.ServerDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
ReadItemArguments4.ItemDescriptor.ItemID = "SomeUnknownItem"

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.ReadMultipleItems(arguments)

Dim i: For i = LBound(results) To UBound(results)
    Dim VtqResult: Set VtqResult = results(i)
    If Not (VtqResult.Exception Is Nothing) Then
        WScript.Echo "results(" & i & ") *** Failure: " & VtqResult.ErrorMessageBrief
    Else
        WScript.Echo "results(" & i & ").Vtq.ToString(): " & VtqResult.Vtq.ToString()
    End If
Next

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

.NET

COM

Conceptual

Examples - OPC Data Access

Examples - OPC Unified Architecture