Abstract: Provided is an alarm device capable of performing transmission and reception reliably while suppressing an amount of current consumption. An alarm device (100) includes: a fire detection circuit (7); a control circuit (1); and a transmitting/receiving circuit (5). The transmitting/receiving circuit (5) transmits the status signal to the another alarm device (100) with a transmission pattern formed by combining transmission periods and transmission suspension periods a predetermined number of times, and receives the status signal transmitted by the another alarm device (100) in an intermittent reception cycle. A time length of each of the transmission periods and the transmission suspension periods is set so that the another alarm device (100) that has failed to receive the status signal transmitted in a first intermittent reception cycle can receive the status signal in a second intermittent reception cycle and subsequent intermittent reception cycles.

Abstract: An alarm system and an alarm device that are capable of enhancing a fail-safe function. A fire alarm device (A) operating as a master unit transmits a switching request signal to fire alarm devices operating as slave units at a predetermined timing. The switching request signal contains at least an own address and an address of a fire alarm device (B) that is to operate as the master unit next (S20). Upon reception of the switching request signal, among the fire alarm devices operating as the slave units, the fire alarm device (B) that is to operate as the master unit next judges whether or not switching is possible based on switching availability judgment information for judging whether or not switching to the master unit is possible (S30), and, when it is judged that switching is possible, starts operating as the master unit (S31).

Abstract: Provided is an alarm device capable of performing transmission and reception reliably while suppressing an amount of current consumption. An alarm device (100) includes: a fire detection circuit (7); a control circuit (1); and a transmitting/receiving circuit (5). The transmitting/receiving circuit (5) transmits the status signal to the another alarm device (100) with a transmission pattern formed by combining transmission periods and transmission suspension periods a predetermined number of times, and receives the status signal transmitted by the another alarm device (100) in an intermittent reception cycle. A time length of each of the transmission periods and the transmission suspension periods is set so that the another alarm device (100) that has failed to receive the status signal transmitted in a first intermittent reception cycle can receive the status signal in a second intermittent reception cycle and subsequent intermittent reception cycles.

Abstract: Provided are an alarm system and an alarm device which are capable of enhancing a fail-safe function. A fire alarm device (A) operating as a master unit transmits a switching request signal to fire alarm devices operating as slave units at a predetermined timing, the switching request signal containing at least an own address and an address of a fire alarm device (B) that is to operate as the master unit next (S20). Upon reception of the switching request signal, among the fire alarm devices operating as the slave units, the fire alarm device (B) that is to operate as the master unit next judges whether or not switching is possible based on switching availability judgment information for judging whether or not the switching to the master unit is possible (S30), and, when it is judged that the switching is possible, starts operating as the master unit (S31).