SMART TAPS FOR A SINGLE-WIRE INDUSTRIAL SAFETY SYSTEM

A single-wire safety system is provided that yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay acting as a communications master device and one or more safety devices connected in series with the safety relay via a single-wire communication circuit. A smart tap device is used to interface safety devices that are not compliant with the single-wire protocol to the single-wire channel. The safety device or smart tap device farthest from the safety relay on the safety circuit modulates a safety signal with a recognizable pulse pattern that traverses the single-wire safety circuit to the safety relay via the intermediate safety devices or smart taps. The safety relay maintains safety mode as long as the pulse pattern is received and recognized. The architecture allows bi-directional communication of initialization, configuration, and diagnostic messages over the single-wire safety channel.