Examples - OPC XML-DA - Get values of multiple properties

The example below combines the ability to browse for items with getting the data type property for each of the items obtained, for OPC XML-DA Servers.

// This example shows how to obtain a data type of all OPC XML-DA items under a branch.

using System;
using System.Linq;
using OpcLabs.BaseLib.ComInterop;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.AddressSpace;

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

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

            // Browse for all leaves under the "Static/Analog Types" branch
            DANodeElementCollection nodeElementCollection = client.BrowseLeaves(serverDescriptor, "Static/Analog Types");

            // Create list of node descriptors, one for each leaf obtained
            DANodeDescriptor[] nodeDescriptorArray = nodeElementCollection
                .Where(element => !element.IsHint)  // filter out hint leafs that do not represent real OPC items (rare)
                .Select(element => new DANodeDescriptor(element))
                .ToArray();

            // Get the value of DataType property; it is a 16-bit signed integer
            ValueResult[] valueResultArray = client.GetMultiplePropertyValues(serverDescriptor,
                nodeDescriptorArray, DAPropertyIds.DataType);

            for (int i = 0; i < valueResultArray.Length; i++)
            {
                DANodeDescriptor nodeDescriptor = nodeDescriptorArray[i];

                // Check if there has been an error getting the property value
                ValueResult valueResult = valueResultArray[i];
                if (!(valueResult.Exception is null))
                {
                    Console.WriteLine("{0} *** Failure: {1}", nodeDescriptor.NodeId, valueResult.Exception.Message);
                    continue;
                }

                // Convert the data type to VarType
                var varType = (VarType)(short)valueResult.Value;

                // Display the obtained data type
                Console.WriteLine("{0}: {1}", nodeDescriptor.ItemId, varType);
            }
        }
    }
}

# This example shows how to obtain a data type of all OPC XML-DA items under a branch.

# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from OpcLabs.BaseLib.ComInterop import *
from OpcLabs.EasyOpc import *
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.DataAccess.OperationModel import *
from OpcLabs.EasyOpc.OperationModel import *


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

# Instantiate the client object.
client = EasyDAClient()

# Browse for all leaves under the "Static/Analog Types" branch
try:
    nodeElementCollection = IEasyDAClientExtension.BrowseLeaves(client,
                                                                serverDescriptor,
                                                                DANodeDescriptor('Static/Analog Types'))
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

# Create list of node descriptors, one for each leaf obtained.
filteredNodeElements = filter(lambda element: not element.IsHint, nodeElementCollection)
nodeDescriptorArray = list(map(lambda element: DANodeDescriptor(element), filteredNodeElements))

# Get the value of DataType property; it is a 16-bit signed integer.
resultArray = IEasyDAClientExtension.GetMultiplePropertyValues(client,
                                                               serverDescriptor,
                                                               nodeDescriptorArray,
                                                               DAPropertyDescriptor.FromInt64(DAPropertyIds.DataType))
# Display results
for i, valueResult in enumerate(resultArray):
    nodeDescriptor = nodeDescriptorArray[i]
    # Check if there has been an error getting the property value.
    if valueResult.Exception is  None:
        # Convert the data type to VarType.
        varType = VarType(valueResult.Value)
        # Display the obtained data type.
        print(nodeDescriptor.ItemId, ': ', varType, sep='')
    else:
        print(nodeDescriptor.ItemId, ' *** Failure: ', valueResult.Exception.Message)

print()
print('Finished')

' This example shows how to obtain a data type of all OPC XML-DA items under a branch.

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

Namespace DataAccess.Xml
    Friend Class GetMultiplePropertyValues
        Public Shared Sub DataTypeXml()
            Dim client = New EasyDAClient()
            Dim serverDescriptor As ServerDescriptor = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"

            ' Browse for all leaves under the "Simulation" branch
            Dim nodeElementCollection = client.BrowseLeaves(serverDescriptor, "Static/Analog Types")

            ' Create list of node descriptors, one for each leaf obtained
            ' filter out hint leafs that do not represent real OPC items (rare)
            Dim nodeDescriptorArray() As DANodeDescriptor = nodeElementCollection _
                .Where(Function(element) Not element.IsHint) _
                .Select(Function(element) New DANodeDescriptor(element)) _
                .ToArray()

            ' Get the value of DataType property; it is a 16-bit signed integer
            Dim valueResultArray() As ValueResult = client.GetMultiplePropertyValues(serverDescriptor,
                    nodeDescriptorArray, DAPropertyIds.DataType)

            For i = 0 To valueResultArray.Length - 1
                Dim nodeDescriptor = nodeDescriptorArray(i)

                ' Check if there has been an error getting the property value
                Dim valueResult As ValueResult = valueResultArray(i)
                If valueResult.Exception IsNot Nothing Then
                    Console.WriteLine("{0} *** Failure: {1}", nodeDescriptor.NodeId, valueResult.Exception.Message)
                    Continue For
                End If

                ' Convert the data type to VarType
                Dim varType = CType(CShort(valueResult.Value), VarType)

                ' Display the obtained data type
                Console.WriteLine("{0}: {1}", nodeDescriptor.ItemId, varType)
            Next i
        End Sub
    End Class
End Namespace

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

Examples - OPC Data Access

Examples - OPC Data Access - Get values of multiple properties

Conceptual

Getting OPC Classic Property Values