I need to get historical data with interval of 30 minutes from 9.30am to 2.30pm within certain date limit. i.e. data of 9.30, 10.00, 10.30, 11.00 and so on, but what I get is data of 9.15, 9.45, 10.15, 10.45 and so on. How can I get the data in my desired way?