Visual Basic (Usage)	Copy Code
Dim instance As OpcXmlDA Dim asyncResult As IAsyncResult Dim InvalidServerSubHandles As String() Dim RItemList As SubscribePolledRefreshReplyItemList() Dim Errors As OPCError() Dim DataBufferOverflow As Boolean Dim value As ReplyBase   value = instance.EndSubscriptionPolledRefresh(asyncResult, InvalidServerSubHandles, RItemList, Errors, DataBufferOverflow)

public ReplyBase EndSubscriptionPolledRefresh( 
   IAsyncResult asyncResult,
   out string[] InvalidServerSubHandles,
   out SubscribePolledRefreshReplyItemList[] RItemList,
   out OPCError[] Errors,
   out bool DataBufferOverflow
)

Parameters

asyncResult

The reference to the pending asynchronous request to wait for.

InvalidServerSubHandles

The server will identify 0 or more ServerSubHandles that were invalid.

RItemList

One RItemList for each subscription of which items have to be returned.
A RItemList for each polled (and valid) subscription handle is sent if the client requested them with “ReturnAllItems”. If “ReturnAllItems” is FALSE, the server only returns Items which had changed. Each RItemList contains the SubscriptionHandle. Within each list the Items will be returned in a relative order based on their relative order in the original Subscribe even if some of the Items are missing because the values have not changed. If there are no values which have changed, the server will respond with a response without any RItemList.
If EnableBuffering = False then the server will send only the latest value that it is maintaining for those changed items.
If EnableBuffering = True then the server will send all value changes (Last Changed Value and any buffered values) for those changed items since the last SubscriptionPolledRefresh.

Errors

An array of OPCError elements with the description of the errors occured in this server call. Errors are only present if Items contain result codes.

DataBufferOverflow

individual items occurred, but not all of these changes could be buffered due to resource limitations. The server is required to provide at least the most recent change for each item that changed since the last update. The individual items will indicate whether they were impacted by this resource limitation. For more details on buffering see the section on Buffered Data and the OPC DA Custom Specification for additional details on this topic.

Return Value

Target Platforms:Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows 7, Windows Server 2008 family

Reference