Abstract: An emergency system for providing an emergency function is described in which the system is required to provide an autonomous and self-diagnostic capability so the system can be tested when not in operation in an emergency situation. A plurality of emergency devices 14 are provided which have transmitters and receivers for producing a mesh network (FIG. 1). Each device 14 has a processor 60 for establishing a preferred wireless communication link of the mesh network to another device 14 for relaying signals and messages. The devices 14 are arranged in subnets 50 and the subnets are also grouped into groups of devices 14 which may cross various subnets 50 so that only one group of devices 14 can be tested at a particular time.

Abstract: An emergency system for providing an emergency function is described in which the system is required to provide an autonomous and self-diagnostic capability so the system can be tested when not in operation in an emergency situation. A plurality of emergency devices 14 are provided which have transmitters and receivers for producing a mesh network (FIG. 1). Each device 14 has a processor 60 for establishing a preferred wireless communication link of the mesh network to another device 14 for relaying signals and messages. The devices 14 are arranged in subnets 50 and the subnets are also grouped into groups of devices 14 which may cross various subnets 50 so that only one group of devices 14 can be tested at a particular time.