GetMultiplePropertyValues(IEasyDAClient,String,String,String,DAPropertyId[]) Method

Gets values of multiple OPC properties of a specified OPC item. Gets values of multiple OPC properties, using individual parameters specifying the OPC server, and OPC Item ID.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function GetMultiplePropertyValues( _
   ByVal client As IEasyDAClient, _
   ByVal machineName As String, _
   ByVal serverClass As String, _
   ByVal itemId As String, _
   ByVal propertyIdArray() As DAPropertyId _
) As ValueResult()

'Usage
 
Dim client As IEasyDAClient
Dim machineName As String
Dim serverClass As String
Dim itemId As String
Dim propertyIdArray() As DAPropertyId
Dim value() As ValueResult
 
value = IEasyDAClientExtension.GetMultiplePropertyValues(client, machineName, serverClass, itemId, propertyIdArray)

[Extension()]
[ElementsNotNull()]
[NotNull()]
public static ValueResult[] GetMultiplePropertyValues( 
   IEasyDAClient client,
   string machineName,
   string serverClass,
   string itemId,
   DAPropertyId[] propertyIdArray
)

[Extension()]
[ElementsNotNull()]
[NotNull()]
public:
static array<ValueResult^>^ GetMultiplePropertyValues( 
   IEasyDAClient^ client,
   String^ machineName,
   String^ serverClass,
   String^ itemId,
   array<DAPropertyId^>^ propertyIdArray
)

Parameters

client: The client object that will perform the operation.
machineName: Name of the machine. Determines the computer on which the OPC server is located. It may be an empty string, in which case the OPC server is assumed to exist on the local computer or at the computer specified for it by DCOM configuration.
serverClass: Contains ProgID of the OPC server to read from.
itemId: The Item ID of the OPC item involved in the operation.
propertyIdArray: Array of Property IDs being obtained

Return Value

The function returns an array of OpcLabs.BaseLib.OperationModel.ValueResult objects. The indices of elements in the output array are the same as those in the input array.

Exceptions

Exception Description

Exception	Description
System.ArgumentNullException	A `null` reference (`Nothing` in Visual Basic) is passed to a method that does not accept it as a valid argument. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

System.ArgumentNullException

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Remarks

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each property is returned in Exception property of each returned OpcLabs.BaseLib.OperationModel.ValueResult element.

This is a multiple-operation method. In a properly written program, it does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated in the result objects returned by the method. For more information, see Multiple-operation Methods and Do not catch any exceptions with asynchronous or multiple-operation methods.

Example

// This example shows how to get value of multiple OPC properties, and handle errors.
//
// Note that some properties may not have a useful value initially (e.g. until the item is activated in a group), which also the
// case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run 
// IEasyDAClient.ReadMultipleItemValues.Main.vbs shortly before this example, in order to obtain better property values. Your 
// code may also subscribe to the items in order to assure that they remain active.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class GetMultiplePropertyValues
    {
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            ServerDescriptor serverDescriptor = "OPCLabs.KitServer.2";

            // Get the values of Timestamp and AccessRights properties of two items.
            ValueResult[] results = client.GetMultiplePropertyValues(new[]
            {
                new DAPropertyArguments(serverDescriptor, "Simulation.Random", DAPropertyDescriptor.Timestamp),
                new DAPropertyArguments(serverDescriptor, "Simulation.Random", DAPropertyDescriptor.AccessRights),
                new DAPropertyArguments(serverDescriptor, "Trends.Ramp (1 min)", DAPropertyDescriptor.Timestamp),
                new DAPropertyArguments(serverDescriptor, "Trends.Ramp (1 min)", DAPropertyDescriptor.AccessRights)
            });

            for (int i = 0; i < results.Length; i++)
            {
                ValueResult valueResult = results[i];
                if (valueResult.Exception is null)
                    Console.WriteLine($"results({i}).Value: {valueResult.Value}");
                else
                    Console.WriteLine($"results({i}).Exception.Message: {valueResult.Exception.Message}");
            }
        }
    }
}

# This example shows how to get value of multiple OPC properties, and handle errors.
#
# Note that some properties may not have a useful value initially (e.g. until the item is activated in a group), which also the
# case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run
# IEasyDAClient.ReadItemValue.Main.vbs shortly before this example, in order to obtain better property values. Your code may
# also subscribe to the item in order to assure that it remains active.
#
# 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 *


serverDescriptor = ServerDescriptor('OPCLabs.KitServer.2')

# Instantiate the client object.
client = EasyDAClient()

# Get the values of Timestamp and AccessRights properties of two items.
resultArray = client.GetMultiplePropertyValues([
    DAPropertyArguments(serverDescriptor, DAItemDescriptor('Simulation.Random'), DAPropertyDescriptor.Timestamp),
    DAPropertyArguments(serverDescriptor, DAItemDescriptor('Simulation.Random'), DAPropertyDescriptor.AccessRights),
    DAPropertyArguments(serverDescriptor, DAItemDescriptor('Trends.Ramp (1 min)'), DAPropertyDescriptor.Timestamp),
    DAPropertyArguments(serverDescriptor, DAItemDescriptor('Trends.Ramp (1 min)'), DAPropertyDescriptor.AccessRights),
    ])

# Display results
for i, valueResult in enumerate(resultArray):
    valueResult = resultArray[i]
    if valueResult.Exception is None:
        print('resultArray[', i, '].Value: ', valueResult.Value, sep='')
    else:
        print('resultArray[', i, '].Exception.Message: ', valueResult.Exception.Message, sep='')

# This example shows how to get value of multiple OPC properties, and handle errors.
#
# Note that some properties may not have a useful value initially (e.g. until the item is activated in a group), which also the
# case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run 
# IEasyDAClient.ReadMultipleItemValues.Main.vbs shortly before this example, in order to obtain better property values. Your 
# code may also subscribe to the items in order to assure that they remain active.
#
# 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.OperationModel
using namespace OpcLabs.EasyOpc
using namespace OpcLabs.EasyOpc.DataAccess
using namespace OpcLabs.EasyOpc.DataAccess.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

$serverDescriptor = New-Object ServerDescriptor("OPCLabs.KitServer.2")

# Get the values of Timestamp and AccessRights properties of two items.
$results = $client.GetMultiplePropertyValues(@(
    (New-Object DAPropertyArguments($serverDescriptor, "Simulation.Random", [DAPropertyDescriptor]::Timestamp)),
    (New-Object DAPropertyArguments($serverDescriptor, "Simulation.Random", [DAPropertyDescriptor]::AccessRights)),
    (New-Object DAPropertyArguments($serverDescriptor, "Trends.Ramp (1 min)", [DAPropertyDescriptor]::Timestamp)),
    (New-Object DAPropertyArguments($serverDescriptor, "Trends.Ramp (1 min)", [DAPropertyDescriptor]::AccessRights))
    ))

for ($i = 0; $i -lt $results.Length; $i++) {
    $valueResult = $results[$i]
    if ($valueResult.Exception -eq $null) {
        Write-Host "results($($i)).Value: $($valueResult.Value)"
    }
    else {
        Write-Host "results($($i)).Exception.Message: $($valueResult.Exception.Message)"
    }
}

' This example shows how to get value of multiple OPC properties, and handle errors.
'
' Note that some properties may not have a useful value initially (e.g. until the item Is activated in a group), which also the
' case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run 
' IEasyDAClient.ReadMultipleItemValues.Main.vbs shortly before this example, in order to obtain better property values. Your 
' code may also subscribe to the items in order to assure that they remain active.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

Namespace DataAccess._EasyDAClient
    Partial Friend Class GetMultiplePropertyValues
        Shared Sub Main1()
            ' Instantiate the client object.
            Dim client = New EasyDAClient()

            Dim serverDescriptor As ServerDescriptor = "OPCLabs.KitServer.2"

            ' Get the values of Timestamp and AccessRights properties of two items.
            Dim results() As ValueResult = client.GetMultiplePropertyValues(New DAPropertyArguments() {
                New DAPropertyArguments(serverDescriptor, "Simulation.Random", DAPropertyDescriptor.Timestamp),
                New DAPropertyArguments(serverDescriptor, "Simulation.Random", DAPropertyDescriptor.AccessRights),
                New DAPropertyArguments(serverDescriptor, "Trends.Ramp (1 min)", DAPropertyDescriptor.Timestamp),
                New DAPropertyArguments(serverDescriptor, "Trends.Ramp (1 min)", DAPropertyDescriptor.AccessRights)
             })

            For i = 0 To results.Length - 1
                Dim valueResult As ValueResult = results(i)
                If valueResult.Exception Is Nothing Then
                    Console.WriteLine($"results({i}).Value: {valueResult.Value}")
                Else
                    Console.WriteLine($"results({i}).Exception.Message: {valueResult.Exception.Message}")
                End If
            Next i

        End Sub

    End Class
End Namespace

CSharp
Python
VB.NET

// This example shows how to get value of multiple OPC XML-DA properties, and handle errors.
//
// Note that some properties may not have a useful value initially (e.g. until the item is activated in a group), which also the
// case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run 
// IEasyDAClient.ReadMultipleItemValues.Main.vbs shortly before this example, in order to obtain better property values. Your 
// code may also subscribe to the items in order to assure that they remain active.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

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

            ServerDescriptor serverDescriptor = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx";

            // Get the values of Timestamp and AccessRights properties of two items.
            ValueResult[] results = client.GetMultiplePropertyValues(new[]
            {
                new DAPropertyArguments(serverDescriptor, "Dynamic/Analog Types/Int", DAPropertyDescriptor.Timestamp),
                new DAPropertyArguments(serverDescriptor, "Dynamic/Analog Types/Int", DAPropertyDescriptor.AccessRights),
                new DAPropertyArguments(serverDescriptor, "Static/Analog Types/Double", DAPropertyDescriptor.Timestamp),
                new DAPropertyArguments(serverDescriptor, "Static/Analog Types/Double", DAPropertyDescriptor.AccessRights)
            });

            for (int i = 0; i < results.Length; i++)
            {
                ValueResult valueResult = results[i];
                if (valueResult.Exception is null)
                    Console.WriteLine($"results({i}).Value: {valueResult.Value}");
                else
                    Console.WriteLine($"results({i}).Exception.Message: {valueResult.Exception.Message}");
            }
        }
    }
}

# This example shows how to get value of multiple OPC XML-DA properties, and handle errors.

# Note that some properties may not have a useful value initially (e.g. until the item is activated in a group), which also the
# case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run 
# IEasyDAClient.ReadMultipleItemValues.Main.vbs shortly before this example, in order to obtain better property values. Your 
# code may also subscribe to the items in order to assure that they remain active.
#
# 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 *


# Instantiate the client object.
client = EasyDAClient()

serverDescriptor = ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx')

# Get the values of Timestamp and AccessRights properties of two items.
results = client.GetMultiplePropertyValues(
    [
        DAPropertyArguments(serverDescriptor, DANodeDescriptor('Dynamic/Analog Types/Int'), DAPropertyDescriptor.Timestamp),
        DAPropertyArguments(serverDescriptor, DANodeDescriptor('Dynamic/Analog Types/Int'), DAPropertyDescriptor.AccessRights),
        DAPropertyArguments(serverDescriptor, DANodeDescriptor('Static/Analog Types/Double'), DAPropertyDescriptor.Timestamp),
        DAPropertyArguments(serverDescriptor, DANodeDescriptor('Static/Analog Types/Double'), DAPropertyDescriptor.AccessRights)
    ])

for i, valueResult in enumerate(results):
    if valueResult.Exception is None:
        print('results[', i, '].Value: ', valueResult.Value, sep='')
    else:
        print('results[', i, '].Exception.Message: ', valueResult.Exception.Message, sep='')

' This example shows how to get value of multiple OPC XML-DA properties, and handle errors.
'
' Note that some properties may not have a useful value initially (e.g. until the item Is activated in a group), which also the
' case with Timestamp property as implemented by the demo server. This behavior is server-dependent, and normal. You can run 
' IEasyDAClient.ReadMultipleItemValues.Main.vbs shortly before this example, in order to obtain better property values. Your 
' code may also subscribe to the items in order to assure that they remain active.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

Namespace DataAccess.Xml
    Partial Friend Class GetMultiplePropertyValues
        Shared Sub Main1Xml()
            ' Instantiate the client object.
            Dim client = New EasyDAClient()

            Dim serverDescriptor As ServerDescriptor = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"

            ' Get the values of Timestamp and AccessRights properties of two items.
            Dim results() As ValueResult = client.GetMultiplePropertyValues(New DAPropertyArguments() {
                New DAPropertyArguments(serverDescriptor, "Dynamic/Analog Types/Int", DAPropertyDescriptor.Timestamp),
                New DAPropertyArguments(serverDescriptor, "Dynamic/Analog Types/Int", DAPropertyDescriptor.AccessRights),
                New DAPropertyArguments(serverDescriptor, "Static/Analog Types/Double", DAPropertyDescriptor.Timestamp),
                New DAPropertyArguments(serverDescriptor, "Static/Analog Types/Double", DAPropertyDescriptor.AccessRights)
             })

            For i = 0 To results.Length - 1
                Dim valueResult As ValueResult = results(i)
                If valueResult.Exception Is Nothing Then
                    Console.WriteLine($"results({i}).Value: {valueResult.Value}")
                Else
                    Console.WriteLine($"results({i}).Exception.Message: {valueResult.Exception.Message}")
                End If
            Next i

        End Sub

    End Class
End Namespace

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

Reference

IEasyDAClientExtension Class
IEasyDAClientExtension Members
Overload List

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