This method is called when the client accesses items that do not yet exist in the server's cache. OPC DA V2 clients typically first call AddItems() or ValidateItems(). OPC DA V3 client may access items directly using the ItemIO read/write functions. In XML DA the calls directly specify the item ID.
If ValidateMode 'ALWAYS' is configured then the method is called for each client call, even if the item exists in the server cache. The access can be denied for a specific client by returning an error code in err[] for such items. This module can: - add the item to the servers real address space and return success. For each item to be added the callback method 'AddItem' has to be called. - return error for all or some items
Syntax
| Visual Basic (Declaration) | |
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Public Overloads Function ValidateItems( _ ByVal instanceHandle As Integer, _ ByVal FullItemId() As String, _ ByVal reason As Integer, _ ByRef err As Integer() _ ) As Integer | |
| C# | |
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public int ValidateItems( int instanceHandle, string[] FullItemId, int reason, out int[] err ) | |
Parameters
- instanceHandle
- Handle the identifies the calling client application. The method GetServerInstancesInfo can be used to get name information for this handle.
- FullItemId
- [in] string array with the names of the items to be validated
- reason
- ValidateReason enumerator indicating why the method is called
- err
- HRESULTS array with success/error code for each requested item
Return Value
the number of successfully added items and/or accessible items.Requirements
Target Platforms: Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows 7, Windows Server 2008 family