What cable do I need?

I need a usb to ttl cable. I need RX, TX, GND and the most important: a pin to control ZERO CROSSING, since my purpose is to

connect a pc through usb to XM10e (ttl-cmos) and so be able to send X10 commands through europe wire system.

What cable do I need?
Thank you so much for your help, since as you see, I'm bit noob

What is the Arduino going to be doing?