PI (PROFIBUS & PROFINET International) already developed PROFIsafe in the 1990s, making fail-safe communication and transfer of process data possible over the same connection. While many users still regarded the new technology skeptically at the time, it has since gained ground over a wide front. Today, PROFIsafe is the world market leader among safety-oriented protocols. PI paved the way to implement completely new possibilities for simplification of machines and systems for users. The technology is stable and mature.
However, until now, fail-save communication via a fieldbus or Industrial Ethernet has been limited to pure master-slave or controller-device architectures. Appropriate couplers are used for reliable transfer between machines and between the controllers used in the machine. But even today, there is no cross-manufacturer standard.
Since PI decided upon OPC UA for connections between controllers in PROFINET networks, it is consistent and necessary to also extend the PROFIsafe mechanisms to OPC UA. By reusing the proven, familiar PROFIsafe mechanisms, PI expects significant simplification for manufacturers who wish to implement PROFIsafe on OPC UA in their PROFINET controllers. This assures high acceptance by both manufacturers and customers, as well as bodies such as certification authorities. Furthermore, the users benefit from an open technology and thus cross-manufacturer communication at the control level for both standard and safety-related data.
Tom Burke, President of the OPC Foundation, confirms: “Functional safety is an essential part of industrial automation systems and the PI solution (PROFIsafe) truly meets and exceeds the OPC Foundation requirements for safety for the OPC UA based controller to controller communication.“
To this end, a memorandum of understanding between the OPC Foundation and PI was signed in the run-up to the SPS IPC Drives trade show in Nuremberg, Germany. The agreed goal is to establish a Joint Working Group of members from both organizations in order to create the PROFIsafe over OPC UA specification for use in fail-save controller to controller communication. This specification will then become an integral component of the OPC UA specification framework. The OPC UA client-server, Pub/Sub and future Pub/Sub services must be mapped with TSN for the various communication requirements.
“Thus, two strong organizations drive the basis for a customer-oriented, open solution in the important Industrie 4.0 scenario of machine to machine communication,” affirms Karsten Schneider, Chairman PI (PROFIBUS & PROFINET International).