A time-stamping layer is provided for time-stamping of events detected in an industrial safety system. The technique implemented by the time-stamping layer uses autonomous device counters and simple arithmetic to label detected events (e.g., safety switching events) with accurate time-stamps without the need to synchronize clocks of the individual safety input devices and safety relay on the safety circuit. In some embodiments, the time-stamping technique is implemented in a single-wire safety system architecture that yields reliable safety device monitoring without the need for dual redundant signal channels.