Read a set of items with the items identified either by the fully qualified item ID or by the server handle that was returned in a previous AddItems call.
If an item is specified by the item id and it does not yet exist in the BGGroup internal list of added items then the item is added by executin AddItems.
The item values are read by executing an asynchronous read and returned to the user as an argument of the completion handler.
Syntax
| Visual Basic (Declaration) | |
|---|---|
Public Overloads Sub Read( _ ByVal itemDefs() As ItemIdentification, _ ByVal tag As Object, _ ByVal onCompleted As OnBGGrpRead _ ) | |
| C# | |
|---|---|
public void Read( ItemIdentification[] itemDefs, object tag, OnBGGrpRead onCompleted ) | |
Parameters
- itemDefs
- Array of item identifiers. Each item may be identified by either:
- the server handle that was returnd in a previous AddItems call.
- the client handle that was specified as a unique value in a previous AddItems call.
- the fully qualified item id. The item is searched in the BGGroup internal list of added items. If the item has not yet been added then it is added by executing an AddItems call. - tag
- This object is passed to the competion handler and allows the user to pass any information that may be needed in the completion handler. Nothing (null) can be specified if the application does not require to pass any information.
- onCompleted
- Completion notification handler. void xxx( BGException ex, int[] requestErrors, OPCItemState[] rslt, object tag ){}