IEC 61511
IEC 61511 and IEC 61508 are very closely connected: in fact, they talk about nearly the same life cycle and the same safety metrics. The main and most obvious difference between the two standards is that IEC 61511 is used primarily by integrators and bases its structure on system performance, while IEC 61508 is used by device manufacturers and bases its structure on the requirements to be provided to the integrator.