The ItemDef object was created in a previous Read or Add call. This method overload is a bit more efficient because no ItemID search as to be done. Only in a SyncIOGroup with many items could be a significant performance gain.
A synchronous OpcGroup read function is executed.
Syntax
| Visual Basic (Declaration) | |
|---|---|
Public Overloads Overridable Function Read( _ ByVal src As OPCDATASOURCE, _ ByVal idef As ItemDef, _ ByRef val As OPCItemState _ ) As Integer | |
| C# | |
|---|---|
public virtual int Read( OPCDATASOURCE src, ItemDef idef, out OPCItemState val ) | |
Parameters
- src
- IN: Cache or Device
- idef
- IN: Item definition object
- val
- OUT: Read item value with quality and timestamp