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L. Krammer, M. Klein, J. Kasberger, W. Kastner:
"A fault-tolerant Communication Scheme for Fire Alarm Systems based on KNX";
Talk: KNX Scientific Conference 2012, Las Palmas, Spain; 2012-11-05 - 2012-11-06; in: "Proceedings KNX Scientific Conference 2012", (2012), 12 pages.

KNX has conquered almost all domains of Home and Building Automation (HBA). However, there are some remaining topics where KNX has not yet been able to gain ground. One important area where KNX is not commonly used is the fire alarm domain. In every building of dedicated size, a Fire Alarm System (FAS) is mandatory. FASs basically consist of sensors and actuators as well as Fire Alarm Control Units (FACUs). Sensors (e.g., alarm buttons, smoke detectors) and the actuators (e.g., fire dampers) are connected to an FACU. In large buildings, one FACU is not sufficient and therefore all FACUs are interconnected in a hierarchical manner. Since life safety is a very critical topic, many national and international standards have to be observed. However, due to the topological nature of KNX, it is not possible to fully satisfy the requirements of the respective standards. A main reason is the missing capability of building redundant systems. For FAS, it is generally demanded that the communication system is fault-tolerant, which means that at least one communication line is allowed to fail, whereby the remaining system must not be influenced.
The paper introduces a communication concept for FASs based on KNX. This concept mainly focuses on safety in terms of fault-tolerance. It addresses the redundant communication of sensors and actuators at the field level and further tackles the high-level communication among FACUs. Thereby, the whole communication is either based on KNX TP1 or, for high-level communication, on KNX IP. The fault-tolerance mechanisms are almost exclusively located at physical layer and data link layer respectively. Thus, the KNX application layer remains unchanged. Only information about faults is propagated upwards. The physical wiring is based on a ring topology, since it is the most efficient way to provide redundancy. Besides the fire alarm application, components of other (non-safety-critical) applications - such as lighting or Heating Ventilation and Air Condition (HVAC) - can be integrated in this system. Finally, the proposed concept is theoretically evaluated by specifying failure scenarios and examining the behavior of the approach.

KNX safety IP redundancy

Project Head Wolfgang Kastner:
Hierarchisch und modular aufgebautes Brandmeldesystem