This Arduino add-allows you to use the Arduino as a DMX master device (transmitter). This board is a simple circuit based around a driver chip (MAX-485 or SN 75176). With XLR 3 pin male DMX output connector. Pin1 = Signal Common, Pin2 = Data-, Pin3 = Data+ The board converts the Arduino signal voltage according to DMX (RS485). Impedance is 100 Ohm.