Event signal transmitter having event signal displaying means

An event signal transmitter for use in an alarm system in which a number of similar transmitters are commonly connected on a single transmission line to a central office. The transmitter is programmable by means of switches to provide a plurality of modes of operation. Alarm and clear events are signaled to the central office by transmitting a predetermined number of rounds of a three digit code number set on a switch matrix. A closing sequence may be selectively employed to reduce undesirable transmission while the protected premises are being closed. An exit delay timer may also be used for this purpose. A line monitor prevents simultaneous transmission by more than one transmitter and a hold out timing period for the monitor is dependent on the time of the occurrence of an event at the transmitter. An override function prevents the transmitter from being indefinitely inhibited from transmitting. A test function is included to determine the condition of sensors before the transmitter is turned on. The power to all circuitry not needed to monitor the sensors or transmission line is turned off until an event signal is to be transmitted.