TÜV SÜD have separately certified that the development processes used by WITTENSTEIN high integrity systems are themselves suitable for use in IEC 61508 projects at the SIL 3 level.
IEC 61508 is an international standard covering the development and usage of electrical, electronic and programmable electronic, safety related systems. In this context, a safety related system is a system that performs one or more safety functions. IEC 61508 covers both hardware and software development, so, with due consideration, safety functions can be performed by software.
The standard defines the analysis, design, implementation, production and test requirements for safety related systems in accordance to the Safety Integrity Level (SIL) assigned to the system. The SIL is assigned according to the risks associated with the use of the system under development, with a
maximum SIL of 4 being assigned to systems with the highest perceived risk. The higher the assigned SIL number the lower the rate of failure must be for all identified unsafe failure modes.Summary of parts one to three:
- Part one defines the necessary development management system – including how the system safety requirements are to be calculated, elicited and defined.
- Part two relates to the hardware aspects of the system development. It contains the techniques required to reduce both systematic and random hardware failures.
- Part three relates to the software aspects of the system development. Unlike hardware, software cannot suffer random failures, and so part three contains the techniques required to guard against systematic failures .