Re: Sending DMX with Max/MSP?
The easiest way is to open the dmxusbpro help file in Max. Change the message where it says "open /dev/cu.usbserial-XXX" to your unique device identifier. Then click on it. You should see the toggle box below with an X if it is successful, the max window should also output some information on a successful connect. From there you should be able to just use the sliders to test some lights in your setup.
Not sure why you're having issues though. I would suggest removing all the drivers and starting clean. Also, I'm assuming you are on a Mac? If you're working on a Windows box, I really have no idea.
Thanks for the clarification on the DMX cables. I remember reading a lot of different articles debating the differences back when I was buying gear. I can confirm using both DMX and mic cables w/ success (my mic cables are well under 50m). I'm also using the 5pin-to-3pin adapter. I do use a 3pin DMX cable though, just to eliminate the potential for ghosts in the machine, I have enough of those in most of my patches ;-)