Estimation and Evaluation of the 1oo4-Architecture for Safety Related Systems
Josef Börcsök and Ali Hayek
Computer Architecture and System Programming, University of Kassel
Wilhelmshöher Allee 71, 34121, Kassel, Germany
j.boercsoek@uni-kassel.de,
ali.hayek@uni-kassel.de
Abstract
In the standard IEC 61508 miscellaneous architectures for
safety related systems are introduced. Depending on the
required safety, reliability and availability levels several
architectures such as 1oo2-, 2oo2-, 1oo3-, and 2oo3-
architectures can be selected. In this paper, the concept and
calculation of a novel architecture is presented. The 1oo4-
architecture (one out of four) represents an advanced safety
architecture, which is 3-failure safe. This means that at least
one of the four channels have to work correctly in order to
trigger the safety function. In order to classify the quality of
the proposed architecture for safety related systems the PFD-
value is calculated. Additionally, the Markov-model for a
1oo4-architecture is introduced and the MTTF-value for this
architecture is calculated. The results are high safety and
high reliability.
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