When this method is called depends on the ValidateMode set in the GetServerParameters() implementation.
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
Overload List
| Overload | Description |
|---|---|
| ValidateItems(String[],Int32,Int32[]) | DEPRECIATED! This overload is is only called if the overload with the client handle argument is not defined. 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. When this method is called depends on the ValidateMode set in the GetServerParameters() implementation. 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 |
| ValidateItems(Int32,String[],Int32,Int32[]) | 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. When this method is called depends on the ValidateMode set in the GetServerParameters() implementation. 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 |
Requirements
Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2