The specification “OPC UA Safety” describes services and protocols for the exchange of data using OPC UA mechanisms. It extends OPC UA to fulfill the requirements of functional safety as defined in the IEC 61508 and IEC 61784-3 series of standards.
Implementing this part allows for detecting all types of communication errors encountered in the lower network layers. In case an error is detected, this information is shared with the application layer which can then act in an appropriate way, e.g. by switching to a safe state.
The specification describes the behavior of the individual endpoints for safe communication, as well as the OPC UA information model which is used to access these endpoints.
OPC UA Safety is application-independent and does not pose requirements on the structure and length of the application data. Application-specific requirements are expected to be described in appropriate companion specifications.
In this first version, communication is based on OPC UA client server, and the main target is controller-controller-communication. However, easy expandability to other OPC UA services (such as pub/sub) and other use-cases (e.g. OPC UA field level communication) has already been considered in the design of OPC UA Safety.