Microplex is an older protocol that uses a single pulse train on one pin, 12VDC on another pin for power to the controller and a ground pin. DMX is differential Rs485 on two pins of a connector. some MPX dimmer packs (I know of a few NSI packs)can be modified by putting a SN75176 chip into it and moving the XLR connector on the logic board to the unoccupied header on the pc board. for some people that cannot change multiplex to DMX there is converters availible on the market for around $200. The avantage of DMX to MPX it is less flakey in some RFI noisey enviroments specially in cable runs of over 200 Ft. DMX has a max cable run of 1000 Ft. and MPX is recommended max run of 150 Ft.