External Hard drives

I am looking for a program that will turn off the USB drives that I have on a cheap laptop that I use as my print server and external HD storage. At the moment I use the on/off switch to turn off the two HD’s that are in cases that convert intenal drives to external. I don’t need the program to turn off the HD’s only place them in hibernate mode when not in use and then turn them back on when access to them is desired. Any help is desired.