I personally have never heard of an NSI brand dimmer that inputs DMX. This is not to say it's impossible, just unlikely. If you don't have the operator's manuals (which you should), you can go to NSI's page and check the specs on your dimmer: http://lms.leviton.com/productsfamlist.aspx?id=3]http://lms.leviton.com/productsfamlist.aspx?id=3
You MUST MAKE SURE that the 3-pin signal is DMX and not the NSI Multiplex protocol. If it's the Multiplex protocol, and you adapt it with a straight cabling adapter, you'll fry your ETC board. But, if you KNOW that it's dmx (I don't know any NSI gear that uses 3pin dmx), you can get a cable 3-5/5-3 cable adapter for under twenty bucks.
If it's the NSI protocol, you'll need a protocol converter. And that's more expensive.
The packs are DD5600's, so they don't use DMX 512, which means ill have to look into either pricing on a diffrent pack system or invest in the convertor, since this is intended to be only a temporary setup until we can get permenant packs for the location, since a dimmer rack is unethical for this application.