A DMX splitter is an electronic box that takes one DMX line and converts it into 2 or more DMX Lines.
This is very handy when you have more than 32 fixtures for a DMX line as the DMX splitter will now allow up to 32 devices on each of the split lines. Also very handy when you have fixtures in different locations and they cannot easily be incorporated in one 'daisy chain'.
Some DMX Splitters have both 3-pin and 5-pin connectors for in and out, others might be either 3-pin or 5-pin.
You should always use a DMX splitter and not use a Y-cable as this can cause reflection on the line and weakens the signal.
The reverse of a DMX Splitter is a DMX Merger.