How to control spin down settings on WD elements USB hdd?

spin wdAfter about 20 mins the unit did go into standby mode (the front LED changed from a static blue to a slow, pulsating blue and the drive spinning noise was absent). Then, when II’d like to know if there is a setting within Windows 7 that will allow the 2 external hard drives in my Western Dital My Book DuoMirror to stay spinning longer.