How do I disable drives?

I think the idea (suggested by Tim G.) to disconnect my stepper
drives (with a relay) when my controller software is inactive is a
good one. Which line(s) should I switch (5v or motor DC or other)?
I'm using CMD-260 drives. Should I use a relay to put 5v across the
enable' pin until I want the drive to be activated?

Thanks in advance,
Jeff