If you want DeltaV Device Commissioner to sense new devices periodically, click the down arrow at the right of the Sense New HART Devices button, and either select one of the preset intervals or click Custom and enter a custom interval.
Alternatively, if the currently active auto-commissioning policy allows modification of commissioning mode defaults in DeltaV Device Commissioner, the following control appears at the bottom of DeltaV Device Commissioner:
You can click the Settings button at the right of this control and then use automatic commissioning preferences to configure periodic sensing.