string connectionString = BLTutela.BLclsDatabaseConfigurations.GetDefaultConnectionString();
dataSource.ConnectionString = connectionString;
dataSource.SelectParameters["ReportFromDate"].DefaultValue = reportFromDateValue.Date.ToString();
...
GridView1.DataSource = dataSource;
GridView1.DataBind();

<connectionStrings>
 <add name="ConnectionString" connectionString="Data Source=;Initial Catalog=;Persist Security Info=True;User ID=;Password=;Connect Timeout=200" providerName="System.Data.SqlClient"/>
</connectionStrings>

protected void SqlDataSource1_Selecting(object sender,
SqlDataSourceSelectingEventArgs e)
{
   e.Command.CommandTimeout = 200;
}