A single-wire safety system architecture yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay and one or more compatible safety input devices connected in series with the safety relay via a single-wire communication circuit. A safety signal with a recognizable pulse pattern traverses the single-wire safety circuit to the safety relay via the safety devices. The safety relay opens its contactors and deenergizes its associated industrial equipment if the pulse pattern is not received and recognized. The safety relay can also be configured to initiate a global emergency stop in response to a loss of a safety function by one of its safety input devices, the global emergency stop instructing other safety relays of other safety circuits to open their contactors and enter safe mode.