OPC Studio User's Guide and Reference
DAClientItemSource Constructor(ServerDescriptor,DAItemDescriptor,DAGroupParameters)



OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.DataAccess.LiveMapping Namespace > DAClientItemSource Class > DAClientItemSource Constructor : DAClientItemSource Constructor(ServerDescriptor,DAItemDescriptor,DAGroupParameters)
The OPC server involved in the operation.

Because the OpcLabs.EasyOpc.ServerDescriptor has an implicit conversion from System.Guid, System.String and OpcLabs.EasyOpc.ServerElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a GUID (representing the CLSID of the server), a string (representing the so-called OPC server descriptor string, such as a ProgID or the URL of the server), or a OpcLabs.EasyOpc.ServerElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC server descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.ServerDescriptor.FromGuid, OpcLabs.EasyOpc.ServerDescriptor.FromString or OpcLabs.EasyOpc.ServerDescriptor.FromServerElement static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

The OPC item involved in the operation.

Because the OpcLabs.EasyOpc.DataAccess.DAItemDescriptor has an implicit conversion from System.String and OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the qualified name of the node), or a OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC DA item descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.DataAccess.DAItemDescriptor.FromString or OpcLabs.EasyOpc.DataAccess.DAItemDescriptor.FromDANodeElement static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

An object containing subscription parameters, such as the requested update rate.

Because the OpcLabs.EasyOpc.DataAccess.DAGroupParameters has an implicit conversion from System.Int32, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use an integer (representing the requested update rate in milliseconds) in place of this parameter, and the corresponding OPC DA group parameters object will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.DataAccess.DAGroupParameters.DAGroupParameters Constructor(Int32) constructor instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

Initializes a new instance of the class, with given OPC server and item descriptors, and subscription (OPC group) parameters.
Syntax
'Declaration
 
Public Function New( _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal itemDescriptor As DAItemDescriptor, _
   ByVal groupParameters As DAGroupParameters _
)
'Usage
 
Dim serverDescriptor As ServerDescriptor
Dim itemDescriptor As DAItemDescriptor
Dim groupParameters As DAGroupParameters
 
Dim instance As New DAClientItemSource(serverDescriptor, itemDescriptor, groupParameters)

Parameters

serverDescriptor
The OPC server involved in the operation.

Because the OpcLabs.EasyOpc.ServerDescriptor has an implicit conversion from System.Guid, System.String and OpcLabs.EasyOpc.ServerElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a GUID (representing the CLSID of the server), a string (representing the so-called OPC server descriptor string, such as a ProgID or the URL of the server), or a OpcLabs.EasyOpc.ServerElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC server descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.ServerDescriptor.FromGuid, OpcLabs.EasyOpc.ServerDescriptor.FromString or OpcLabs.EasyOpc.ServerDescriptor.FromServerElement static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

itemDescriptor
The OPC item involved in the operation.

Because the OpcLabs.EasyOpc.DataAccess.DAItemDescriptor has an implicit conversion from System.String and OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the qualified name of the node), or a OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC DA item descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.DataAccess.DAItemDescriptor.FromString or OpcLabs.EasyOpc.DataAccess.DAItemDescriptor.FromDANodeElement static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

groupParameters
An object containing subscription parameters, such as the requested update rate.

Because the OpcLabs.EasyOpc.DataAccess.DAGroupParameters has an implicit conversion from System.Int32, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use an integer (representing the requested update rate in milliseconds) in place of this parameter, and the corresponding OPC DA group parameters object will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the OpcLabs.EasyOpc.DataAccess.DAGroupParameters.DAGroupParameters Constructor(Int32) constructor instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

Requirements

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

See Also