The Edwards 5531M Adaptatone Millennium is a heavy-duty industrial, tone-selectable, signaling device capable of producing volume-controlled, high-decibel tones, four tones can be activated from field-wired, normally open contacts, or a 24VDC external voltage source such as the output of a PLC. Normally open contacts can be obtained from the Cat. No. 5538-4 and/or Cat. No. 5538-4R Adaptatone Signal Actuators. The unit uses a microprocessor circuit to create 55 distinctive tones, by setting miniature dip switches within the unit. The programmed tones operate on a pyramid-type priority system. Designed for industrial applications. Typical applications include emergency warning systems, plant evacuation and security alarms, process monitoring, shift notifications, and paging signals. The 5531M is designed for either 1/2 in. (13mm) conduit or surface mounting.