This European Standard specifies a safety-related communication layer (services and protocol) based on EN 50325-4. This European Standard applies to networks based on EN 50325-4 providing safety-related communication capabilities between devices in a safety-related system in accordance with the requirements of EN 61508 series for functional safety. The services and protocols defined in this standard are intended to extend those defined in EN 50325-4. These services and protocols may be used in various applications such as manufacturing, machinery, medical, mobile machinery and process control.