This document specifies requirements, test methods and performance criteria for input/output devices for use on the transmission paths of fire detection and fire alarm systems installed in buildings. Input/output devices, used in this document cover a wide range of different types of devices, which are intended for different applications, and may therefore have different functions. This specification does not therefore include detailed functional requirements for the input/output devices but requires that their function is sufficiently specified by the manufacturer and that they function correctly in accordance with the manufacturer's specification. It is expected that these devices will be installed in the same types of environments as detectors and similar environmental conditioning is therefore applied. This document does not apply radio linked input output devices .