Until now, fail-safe communication via a fieldbus or Industrial Ethernet has been limited to pure master-slave or controller-device architectures. Corresponding couplers are used for safe transmission between machines and thus between the controllers used there. However, there is still no manufacturer-independent standard.

"Because PI has opted for OPC UA for connections between controllers in Profinet networks, it is logical and necessary to extend the mechanisms of Profisafe to OPC UA," explained Karsten Schneider, CEO of PI, at SPS IPC Drives 2017. "By reusing the proven and well-known mechanisms of Profisafe, PI expects a significant simplification for manufacturers who want to implement Profisafe on OPC UA in their Profinet controllers." Users benefit from an open technology and therefore manufacturer-independent communication at controller level, both for standard and safety-related data.

As a first step, the OPC Foundation and PI signed a Memorandum of Understanding prior to SPS IPC Drives. The agreed goal is to establish a Joint Working Group consisting of members of both organizations in order to create the "Profisafe over OPC UA" specification for fail-safe controller-controller communication. This specification is then to become an integral part of the OPC UA Specification Framework. In order to meet the communication requirements, the OPC UA services client/server, pub/sub and, in future, pub/sub with TSN must be mapped.

"Functional safety is an essential part of industrial automation systems," emphasized Tom Burke, President of the OPC Foundation. "Profisafe is a solution that meets and exceeds all OPC Foundation requirements for fail-safe controller-controller communication with OPC UA."