The Edwards 5530MD-24AW Adaptatone Millennium is a heavy duty industrial, tone-selectable, signaling device intended primarily for use in fire alarm systems and other applications requiring electrical supervision of signaling circuit field wiring. It uses a microprocessor circuit to create 27 distinctive tones. A single tone may be selected by setting a miniature dip switch within the unit. The Adaptatone Millennium can be activated from field-wired, normally open contacts, or a 24VDC external voltage source such as an output of a PLC or Fire/Security panel. Normally open contacts can be obtianed from the Cat. No. 5538-4 and/or Cat. No. 5538-4R Adaptatone Signal Actuators.