public Task<T> WaitForAsync<T>(string host, string serverName, string tagID, T waitFor, ILog logger) where T:struct
        {            
            TaskCompletionSource<T> tcs = new TaskCompletionSource<T>();
            EasyDAClient opcComponent = new EasyDAClient();
            opcComponent.Isolated = true;
            opcComponent.InstanceParameters.Mode.AllowAsynchronousMethod = false;

            opcComponent.ItemChanged += (s, e) =>
            {
                try
                {
                    if (e.Vtq != null)
                    {
                        if (e.Vtq.Quality.IsGood())
                        {
                            string itemId = e.ItemDescriptor.ItemId;
                            if (e.Vtq.Value is T && waitFor.Equals(e.Vtq.Value))
                            {
                                tcs.SetResult((T)e.Vtq.Value);
                                opcComponent.UnsubscribeAllItems();
                                opcComponent.Dispose();
                            }
                            else if (e.Vtq.Value is Int16 || (Int16)e.Vtq.Value > 90)
                            {
                                if ((Int16)e.Vtq.Value == (Int16)MES.Constants.RESULTCODE.RECIPE_ERROR)
                                {
                                    tcs.SetException(new MES.Common.Exceptions.PlcErrorCodeException(MES.Constants.RESULTCODE.RECIPE_ERROR, "Unknown recipe"));
                                    opcComponent.UnsubscribeAllItems();
                                    opcComponent.Dispose();
                                }
                                if ((Int16)e.Vtq.Value == (Int16)MES.Constants.RESULTCODE.OUT_OF_MATERIAL)
                                {
                                    tcs.SetException(new MES.Common.Exceptions.PlcErrorCodeException(MES.Constants.RESULTCODE.OUT_OF_MATERIAL, "Out of material"));
                                    opcComponent.UnsubscribeAllItems();
                                    opcComponent.Dispose();
                                }
                            }
                        }
                        else
                        {
                            logger.DebugFormat("Quality WaitForAsync : {0}", e.Vtq.Quality.StatusBitField);
                        }
                    }
                }
                catch(Exception ex)
                {
                    logger.Fatal("OPCReader.WaitForAsync", ex);
                    throw;
                }
            };            
            opcComponent.SubscribeItem(host, serverName, tagID, 300);

            return tcs.Task;
         
        }