motor grounding and DB9 connector question

Hi folks,

I have noticed my surplus motors have ground straps attached. I was
wondering if folks grounded their motors, and if so, to the machine
or to the power ground at the control box.

Also, I have been designing my system with DB9 connectors for the
motor connections. I will be running 55V at a maximum of 7amps and
want to make sure the connectors are up to the task. Does anyone
have a link to specs for common connectors? I've searched google for
a while now and have had no luck.

The machine is coming along very nicely. I'll post pictures or a
link to a website soon.

Thanks in advance for any help.

Chris