1. A method of automatically demanding the signal measured value and the signal identification in a haxard alarm system having a central unit and at least one signal line (ML) to which a plurality of signals (M) are connected wherein during cyclic interrogation, in each signal (M) a timing element (T1) which can be influenced by the signal measured value by means of a measuring transducer (MW) is connected to the signal line (ML), and the signal address is derived from the number of the increases in the signal line current (1L) which are effected in the central unit thereby, and the signal measured value is derived from the length of the respective switching delay, where an additional current pulse is produced by means of an assigned timing element (T2) as a result of temporary connection of a load resistor (R) to the signal line (ML), characterised in that the pulse shape of the additional current pulse is changed for a signal identification (e.g. signal type, signal state) in a predetermined and defined manner and the identification value characteristic of the respective signal (M), is derived therefrom in the central unit.
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