Use on ETC SR48 Rack?

[MCDELTAT]

Hey guys, I was wondering if any of you on here have ever been able to
interface with a lighting rack. I got a great code made up on my
Arduino using the DmxSimple library that works on all my DMX fixtures
(Mac 2k (4), Chauvet Min Spot, American DJ Strobe) but can't seem to
communicate correctly with my lighting rack.

I'm using a 6 year old ETC SR48 rack (just an older command module is
all). When I plug in my normal Leprecon LP-X console and I get the
usual message found in the "about" section of my rack ("DMX Port A:
OK") whereas when I try it using my Arduino it simply says "DMX Port
A: No Input" meaning it didn't find it at all. I'm in the process of
ordering new cables and 3-5 pin converters for new fixtures anyways
and will see if thats the problem, but my suspicion is more towards
this:

Do I have to set a com port to send to when interfacing with a
lighting rack? If so, how should I go about doing that? I doubt this
library will be able to help me much.

Thanks for any help/direction you may give me in advance.

-Aaron C.
MCDELTAT Productions