Alternate Access to OPC-DA Properties

The GetPropertyValueDictionary method allows you to obtain a dictionary of property values for a given OPC item, where a key to the dictionary is the property Id. You can pass in a set of property Ids that you are interested in, or have the method obtain all well-known OPC properties. You can then easily extract the value of any property by looking it up in a dictionary (as opposed to having to numerically index into an array, as with the base GetMultiplePropertyValues method).

// This example shows how to obtain a dictionary of OPC property values for an OPC item, and extract property values.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

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

            // Get dictionary of property values, for all well-known properties
            DAPropertyValueDictionary propertyValueDictionary;
            try
            {
                propertyValueDictionary = client.GetPropertyValueDictionary("", "OPCLabs.KitServer.2", "Simulation.Random");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            // Display some of the obtained property values
            // The production code should also check for the .Exception first, before getting .Value
            Console.WriteLine("propertyValueDictionary[DAPropertyId.AccessRights].Value: {0}",
                propertyValueDictionary[DAPropertyIds.AccessRights].Value);
            Console.WriteLine("propertyValueDictionary[DAPropertyId.DataType].Value: {0}",
                propertyValueDictionary[DAPropertyIds.DataType].Value);
            Console.WriteLine("propertyValueDictionary[DAPropertyId.Timestamp].Value: {0}",
                propertyValueDictionary[DAPropertyIds.Timestamp].Value);
        }
    }
}

# This example shows how to obtain a dictionary of OPC property values for an OPC item, and extract property values.
#
# 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.DataAccess import *
from OpcLabs.EasyOpc.DataAccess.Extensions import *
from OpcLabs.EasyOpc.OperationModel import *


# Instantiate the client object.
client = EasyDAClient()

# Get dictionary of property values, for all well-known properties.
try:
    propertyValueDictionary = IEasyDAClientExtension2.GetPropertyValueDictionary(client,
        '', 'OPCLabs.KitServer.2', 'Simulation.Random')
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

# Display some of the obtained property values.
# The production code should also check for the .Exception first, before getting .Value
print('propertyValueDictionary[DAPropertyId.AccessRights].Value: ',
    propertyValueDictionary.get_Item(DAPropertyId(DAPropertyIds.AccessRights)).Value, sep='')
print('propertyValueDictionary[DAPropertyId.DataType].Value: ',
    propertyValueDictionary.get_Item(DAPropertyId(DAPropertyIds.DataType)).Value, sep='')
print('propertyValueDictionary[DAPropertyId.Timestamp].Value: ',
    propertyValueDictionary.get_Item(DAPropertyId(DAPropertyIds.Timestamp)).Value, sep='')

print('Finished.')

' This example shows how to obtain a dictionary of OPC property values for an OPC item, and extract property values.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

Namespace DataAccess._EasyDAClientExtension
    Friend Class GetPropertyValueDictionary
        Public Shared Sub Main1()
            Dim client = New EasyDAClient()

            ' Get dictionary of property values, for all well-known properties
            Dim propertyValueDictionary As DAPropertyValueDictionary
            Try
                propertyValueDictionary = client.GetPropertyValueDictionary("", "OPCLabs.KitServer.2", "Simulation.Random")
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try

            ' Display some of the obtained property values
            ' The production code should also check for the .Exception first, before getting .Value
            Console.WriteLine("propertyValueDictionary[DAPropertyId.AccessRights].Value: {0}", propertyValueDictionary(DAPropertyIds.AccessRights).Value)
            Console.WriteLine("propertyValueDictionary[DAPropertyId.DataType].Value: {0}", propertyValueDictionary(DAPropertyIds.DataType).Value)
            Console.WriteLine("propertyValueDictionary[DAPropertyId.Timestamp].Value: {0}", propertyValueDictionary(DAPropertyIds.Timestamp).Value)
        End Sub
    End Class
End Namespace

The GetItemPropertyRecord method allows you to obtain a structure filled in with property values for a given OPC item. It can retrieve all well-known properties at once, or you can pass in a set of property Ids that you are interested in. You can then simply use the properties in the resulting DAItemPropertyRecord structure, without further looking up the values in any way.

// This example shows how to obtain a structure containing property values for an OPC item, and display some property values.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

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

            // Get a structure containing values of all well-known properties
            DAItemPropertyRecord itemPropertyRecord;
            try
            {
                itemPropertyRecord = client.GetItemPropertyRecord("", "OPCLabs.KitServer.2", "Simulation.Random");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            // Display some of the obtained property values
            Console.WriteLine("itemPropertyRecord.AccessRights: {0}", itemPropertyRecord.AccessRights);
            Console.WriteLine("itemPropertyRecord.DataType: {0}", itemPropertyRecord.DataType);
            Console.WriteLine("itemPropertyRecord.Timestamp: {0}", itemPropertyRecord.Timestamp);
        }
    }
}

# This example shows how to obtain a structure containing property values for an OPC item, and display some property
# values.
#
# 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.DataAccess import *
from OpcLabs.EasyOpc.DataAccess.Extensions import *
from OpcLabs.EasyOpc.OperationModel import *


# Instantiate the client object.
client = EasyDAClient()

# Get a structure containing values of all well-known properties.
try:
    itemPropertyRecord = IEasyDAClientExtension2.GetItemPropertyRecord(client,
                                                                       '', 'OPCLabs.KitServer.2', 'Simulation.Random')
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

# Display some of the obtained property values.
print('itemPropertyRecord.AccessRights: ', itemPropertyRecord.AccessRights, sep='')
print('itemPropertyRecord.DataType: ', itemPropertyRecord.DataType, sep='')
print('itemPropertyRecord.Timestamp: ', itemPropertyRecord.Timestamp, sep='')

print('Finished.')

' This example shows how to obtain a structure containing property values for an OPC item, and display some property values.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

Namespace DataAccess._EasyDAClientExtension
    Friend Class GetItemPropertyRecord
        Public Shared Sub Main1()
            Dim client = New EasyDAClient()

            ' Get a structure containing values of all well-known properties
            Dim itemPropertyRecord As DAItemPropertyRecord
            Try
                itemPropertyRecord = client.GetItemPropertyRecord("", "OPCLabs.KitServer.2", "Simulation.Random")
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try

            ' Display some of the obtained property values
            Console.WriteLine("itemPropertyRecord.AccessRights: {0}", itemPropertyRecord.AccessRights)
            Console.WriteLine("itemPropertyRecord.DataType: {0}", itemPropertyRecord.DataType)
            Console.WriteLine("itemPropertyRecord.Timestamp: {0}", itemPropertyRecord.Timestamp)
        End Sub
    End Class
End Namespace

The static DAPropertyIDSet class gives you an easy way to provide pre-defined sets of properties to the above methods. There are well-known sets such as the Basic property set, Extension set, or Alarms and Events property set. It also allows you to combine the property sets together (a union operation), with the Add method or the ‘+’ operator.