for DMX runs over 100 feet it is always recommended to use a opto branch 4.
Using one of these will help ensure strong signal across long dmx runs like you have. ESPECIALLY if you are not using all dmx cables. The way these interfaces work is by USB Power, and USb power while strong enough to output dmx is not gonna keep the same strength as a console plugged into a 120 volt wall outlet. I'm sure chris or serra ava will be happy to elaborate on this for you.