OPCDA.NET Reference Manual
AddRefreshGroup(RefreshEventHandler) Method
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OpcDaNetUA.Net4 Assembly > OPCDA.NET Namespace > OpcServer Class > AddRefreshGroup Method : AddRefreshGroup(RefreshEventHandler) Method

UserHnd
User data callback handler. May be null (VB Nothing) if no user event handling is required. In this case onl the RefreshGroup internal value cache is updated in the callback.

Glossary Item Box

Create a RefreshGroup object with an update rate of 500 ms.
The RefreshGroup class offers a set of functions for simplified asynchronuous server access. These methods are not defined in the OPC standard and the RefreshGroup class is actually a software layer above the OpcGroup class. It handles the OPC group management functions internally and allows a simple access to items by just specifiyng the item name. A data cache is maintained for all added or referenced items. This cache is updated from the OPC group data callback function. The user can always read up-to-date values from the cache but also can attach his own callback handler.

Syntax

Visual Basic (Declaration) 
Public Overloads Function AddRefreshGroup( _
   ByVal UserHnd As RefreshEventHandler _
) As RefreshGroup
C# 
public RefreshGroup AddRefreshGroup( 
   RefreshEventHandler UserHnd
)

Parameters

UserHnd
User data callback handler. May be null (VB Nothing) if no user event handling is required. In this case onl the RefreshGroup internal value cache is updated in the callback.

Return Value

RefreshGroup object

Requirements

Target Platforms: Windows 7/8/10, Windows Server 2003/2008/2012/2016, .NET 4.x

See Also

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