The OPC Web Refresh component is required on every WebForm with an OPCWebTrend component to provide real-time update as the specified RefreshRate. This component is not required if you plan to only use the history feature of OPC Web Trend.NET.
To add an OPC Web Refresh select the OPCWebRefresh component from the ToolBox and place it on any WebForm that you plan to use other OPC Web Controls on. Leave the ID at the default of OPCWebRefresh1, this way when values are set such as a OPCWebControlsButton SetValue an immediate refresh will occur regardless of the RefreshRate. See Add OPC Web Controls Components to Visual Studio.NET to add the OPC Web Refresh to the ToolBox.