Asynchronous methods (such as SubscribeXXXX), or methods that work on multiple elements at once (such as EasyDAClient.ReadMultipleItems) only throw program execution-related errors (such as OutOfMemoryException, or StackOverflowException), and argument validation exceptions, such as ArgumentException. The OPC-related exceptions are reported in a different way: By event notifications or callbacks (for asynchronous methods), or in the OperationResult.Exception properties of the methods return value array (for multiple-operation methods).

By catching exceptions in this case, you could hide programming or catastrophic errors that should not be handled in this way. For more information, see Errors and Multiple-Element Operations.