Abstract: An improved alarm system and method for use in a fire detection system of the type including at least one sensor for sensing the level of a parameter of a fire condition such as heat or smoke density and which transmits electrical signals indicative of the sensed levels over a communication link. The alarm system and method provides for indicating a first alarm condition by receiving electrical signals from the sensor, keeping time from the time that the parameter reaches a first level, and indicating the first alarm condition when the parameter reaches a second level within a first predetermined time period. The second level has a magnitude greater than the first level. The alarm system and method also indicates a first alarm condition corresponding to a third level of the parameter prior to the third parameter level being reached.

Abstract: A repeater circuit for repeating data on a communication channel, the repeater circuit having two receiver/driver circuits arranged in repeating fashion and having a control circuit for maintaining the receiver/driver circuits in a listening mode, for switching one of the receiver/driver circuits to a transmitting mode when the other of the receiver/driver circuits receives data, and for maintaining the switched receiver/driver circuits switched by an amount of time required for the bus connected to the switched receiver/driver circuit to return to its normal state after the cessation of transmitted data.