A Practical Analytical Approach to Increase Confidence in PLD-Based Systems Safety Analysis

The use of programmable logic devices (PLDs) in safety-critical systems has meaningfully increased over the past years, driven by advantages such as reduced development costs and time-to-market. Despite such increasing use, current standards that support the development of safety-critical systems have still not appropriately addressed how to certificate PLD-based systems. Recent bibliography on the use of PLDs in safety-critical systems has not filled this gap as well, reinforcing the need for a safety analysis methodology for PLD-based safety-critical systems. This paper proposes an extension of the practical analytical approach presented in 2015 by Vismari et al., inserting the safety analysis of PLDs into a broader system safety analysis process. The PLD safety analysis is based on the code inspection of the hardware description source code. It checks for inappropriate coding practices and aids in minimizing the exposure of the system to an unsafe state due to an inadequate PLD design. A case study based on the authors' experience by applying the proposed approach in real independent safety analysis projects of safety-critical systems, together with its results, is then presented. Based on such results, the proposed approach is deemed appropriate for the safety analysis of PLD-based safety critical systems, supporting its use in a system certification context.