I just started using one of these to send midi data to the stage for an x32.
I got mine from CBI for $90 a pair. I also got the shielded Cat5e cable with ethercon. I've been able to pass audio talk back and headphone cue back on the other two lines.
This is my low budget way of making a FOH split. The console lives on stage with or without a monitor engineer and I can control FOH with the ipad/ midi fader bank.
Here's a link to the CBI version.
http://www.cbicables.com/products/dmx_to_cat__shuttle_snake.aspx LOU