' This example shows how to store current state of the subscribed items in a dictionary. Imports System.Threading Imports OpcLabs.EasyOpc.DataAccess Imports OpcLabs.EasyOpc.DataAccess.OperationModel Namespace DocExamples.DataAccess._EasyDAClient Partial Friend Class SubscribeMultipleItems Public Shared Sub StoreInDictionary() Using client = New EasyDAClient() AddHandler client.ItemChanged, AddressOf client_ItemChanged_StoreInDictionary client.SubscribeMultipleItems(New DAItemGroupArguments() { New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, Nothing), New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 min)", 1000, Nothing), New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Sine (1 min)", 1000, Nothing), New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 1000, Nothing) }) Console.WriteLine("Processing item changed events for 1 minute...") Dim startTickCount As Integer = Environment.TickCount Do Thread.Sleep(5 * 1000) ' Each 5 seconds, display the current state of the items we have subscribed to. SyncLock _serialize Console.WriteLine() For Each pair As KeyValuePair(Of DAItemDescriptor, DAVtqResult) In _vtqResultDictionary Dim itemDescriptor As DAItemDescriptor = pair.Key Dim vtqResult = pair.Value Console.WriteLine($"{itemDescriptor}: {vtqResult}") Next ' The code above shows how you can process the complete contents of the dictionary. In other ' scenarios, you may want to access just a specific entry in the dictionary. You can achieve that ' by indexing the dictionary by the item descriptor of the item you are interested in. End SyncLock Loop While Environment.TickCount < startTickCount + 60 * 1000 End Using End Sub ' Item changed event handler Private Shared Sub client_ItemChanged_StoreInDictionary(ByVal sender As Object, ByVal e As EasyDAItemChangedEventArgs) SyncLock _serialize ' Convert the event arguments to a DAVtq result object, and store it in the dictionary under the key which ' is the item descriptor of the item this item changed event is for. _vtqResultDictionary(e.Arguments.ItemDescriptor) = CType(e, DAVtqResult) End SyncLock End Sub ' Holds last known state of each subscribed item. Private Shared ReadOnly _vtqResultDictionary As New Dictionary(Of DAItemDescriptor, DAVtqResult) ' Synchronization object used to prevent simultaneous access to the dictionary. Private Shared ReadOnly _serialize As New Object End Class