The FireNET® 4127 control panel is an analog addressable fire alarm panel containing 2 or 4 SLC loops with each loop supporting 127 devices of any combination (sensors or modules), and 127 analog sounder bases, for a possible total of 254 points. Communication between devices is transferred through standard cable (shielded or twisted pair is not required). Each panel includes a 5.25 amp power supply and has 4 on board NAC circuits. An RS-485 bus provides communication to the panel network, while the RS-232 interface allows the convenience of programming via a PC. The system will support a variety of Hochiki devices such as photo, ion and heat sensors, which contain a unique, patented sensor design incorporating automatic drift compensation and day/night sensitivity mode. Additional devices include contact monitors, relay controllers, supervised auxiliary output and short circuit isolator modules. In addition, interfaces to conventional detection systems can be established by using a conventional zone-monitoring module.