MS-2 is a two zone conventional fire alarm control panel compatible with the new I3 smoke detectors from System Sensor, and provides such advanced features as drift compensation, maintenance alert, and freeze warning. Automatic synchronization of audio/visual devices is provided, using manufacturer protocol for System Sensor, Wheelock and Gentex appliances. The NAC protocol includes the ability to silence audible devices while strobes continue to flash, using only a single pair of wires.