So I bit the bullet and picked up a DMX-AN, which is Chauvet's Artnet to DMX converter those of you that don't already know.. As I pulled it out of the packaging and plugged everything in, I set up my IP address and sub net as per instructions, and logged onto the 2.0.0.1 setup webpage. Punched in all my info and set the universe on port A as 'output' and universe as # '2'.
I plugged in a par to test, and no DMX signal was coming out of the box. So I double checked everything and re-read all the instructions, but I had done everything right. Then I decided to install showXpress on my windows laptop and see if it was the OS, but same issues there. (more on OS later) I even called Chauvet tech support, and although the agent said he'd call back I never got a call. So I started to mess round with settings and found the issue!
It turns out that in the 2.0.0.1 setup page in your web browser, when declaring your universe the universe numbering starts from zero. (i.e: putting 0 on the setup webpage is really universe #1 in showXpress, and putting 1 on the setup webpage is really universe #2 in showXpress, etc, etc..) So if you want your Xpress512 to be universe #1, and the DMX-AN to be universe #2 in showXpress, on the DMX-AN setup webpage you must set the universe to 1, since U1 is really U2 in showXpress.
I'm not sure if this was intentional by Chauvet, but I know that this is also a common programming mistake. Just something for everyone to beware of, and avoid the frustrations I've had!