XML-DA method to asynchronously get item properties from an XML-DA or OPC-DA server.
Syntax
| Visual Basic (Usage) |  Copy Code |
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Dim instance As OpcXmlDA
Dim ItemIDs() As ItemIdentifier
Dim PropertyNames() As XmlQualifiedName
Dim LocaleID As String
Dim ClientRequestHandle As String
Dim ItemPath As String
Dim ReturnAllProperties As Boolean
Dim ReturnPropertyValues As Boolean
Dim ReturnErrorText As Boolean
Dim callback As AsyncCallback
Dim asyncState As Object
Dim value As IAsyncResult
value = instance.BeginGetProperties(ItemIDs, PropertyNames, LocaleID, ClientRequestHandle, ItemPath, ReturnAllProperties, ReturnPropertyValues, ReturnErrorText, callback, asyncState) |
Parameters
- ItemIDs
- A list of Items for which to get properties.
ItemPath and ItemName together uniquely identify this element in the server’s browse space. If ItemPath is empty, then ItemName by itself is a fully qualified name that uniquely identifies this element. - PropertyNames
- A sequence of qualified property names to be returned. If ReturnAllProperties is true,
PropertyName is ignored and all properties are returned.
- LocaleID
- An optional value supplied by the client that specifies the language for certain return data
(see section LocaleID in OPC specification).
- ClientRequestHandle
- An optional value supplied by the client that will be returned with the response.
In larger and more complex systems it helps the client to associate the replies with the proper requests.
- ItemPath
- ItemPath is a hierarchical parameter. It can be overridden by the ItemPath in the ItemIdentifier.
If ItemPath is Blank or missing at all levels of the hierarchy, then the ItemName is expected to be a fully qualified name.
- ReturnAllProperties
- Server must return all properties which are available. If ReturnAllProperties is true,
PropertyName is ignored.
- ReturnPropertyValues
- Server must return the property values in addition to the property names.
- ReturnErrorText
- If TRUE the server will return verbose error description.
- callback
- Delegate of the method to be called when the asynchronous operation is completed.
- asyncState
- A user-provided object that distinguishes this particular asynchronous request from other requests.
Return Value
An object that supports the IAsyncResult interface stores state information for an asynchronous operation,
and provides a synchronization object to allow threads to be signaled when the operation
Requirements
Target Platforms:Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows 7, Windows Server 2008 family
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See Also
