Right-clicking on the left pane will allow to you select “WhoIs Device”. This will open the Send WhoIs dialog window to allow you to select the low and high range of devices to discover.
For the example above, a WhoIs command for devices 1000-2000 will be sent to the BACnet network. If any devices between that range (inclusive) see the command, they will respond with an Iam message. The network tree will show any new devices found after it is refreshed (F5).