This document specifies a safety communication layer (SCL) allowing safety-related devices to use the services of OPC UA for the safe exchange of safety-related data. A safety device that implements OPC UA Safety correctly will be able to exchange safety-related data and hereby fulfill the requirements of the IEC 61508 series and IEC 61784-3. This document uses a MonitoringNumber, a timeout, a set of IDs and a cyclic redundancy check (CRC)code for the detection of all possible communication errors which can happen in the underlying OPC UA standard transmission system. These safety measures have been quantitatively evaluated and offer a probability of dangerous failure per hour (PFH) and a probability of dangerous failure on demand (PFD) sufficing to build safety-related applications with a safety integrity level of up to SIL 4.

OPC UA Safety itself is an application-independent, general solution. The length and structure of the data sent is defined by the safety application. However, application-dependent companion specifications (addressing for example electro-sensitive protective equipment, electric drives with safety functions, forming presses, robot safety, and automated guided vehicles) are expected to be defined by application-experts in appropriate OPC UA companion specifications.