How to assign a data source
Data sources must be added to business groups before their data can be transferred to Apex.
Prerequisite(s):  
You must have a data source before you can assign it to a business group. If you need to create a data source before continuing, see How to add a data source.
 
To assign a data source:
1. In the web interface, click Configuration > Data.
2. In the Data pane, click the Business Groups tab.
3. Begin editing a business group by clicking its name.
4. In the Edit pane, click the Data Sources tab.
5. Move a probe instance from Available Data Sources to Selected Data Sources using a drag-and-drop operation.
You can repeat the drag-and-drop operation to assign more data sources to the business group.
6. Click the accept icon .
 
Apex contacts the data source to request and retrieve its trending data. The value of Data transfer delay (minutes) at controls the number of minutes to wait after Data transfer period (minutes) finishes before retrieving the trending data.
For example, if Data transfer delay (minutes) is set to 2 minutes, trending data from your assigned data source will begin transferring two minutes after the data source has finished its statistics collection interval.