Plant owners and system integrators assemble complex systems using best-of-breed solutions from multiple vendors in today's modern plants. Successfully integrating products like PLCs, DCS controllers, or PAS applications from different vendors can require a great deal of effort. Industrial automation has not effectively solved this problem to date. UAFX Controller-to-Controller communication delivers a genuinely multi-vendor interoperable, real-time solution.


Figure 9 – Controller-to-Controller communication

The UAFX specification addresses multi-controller environments, as shown in Figure 9. The Controllers in this illustration may be an IPC with visualisation, a PLC, a DCS controller, or something else. All communication partners are modelled as AutomationComponents defined in OPC 10000-81. An AutomationComponent provides an abstract model that allows vendors to describe the Controller's assets, automation functions, and a standard interface for Connections that provides interoperability for exchanging data. AutomationComponents, Assets, and FunctionalEntities also include identification information allowing compatibility to be verified for each Connection.

This release of the UAFX specification defines Connections using OPC UA PubSub for data exchange, including the usage of TSN. Connections using OPC UA Client Server for data exchange are planned for future releases of the specification. Exchanged data can be standard process data or SafetyData. Both bidirectional and unidirectional traffic can be used (see OPC 10000-81). TSN can provide guaranteed bounded latency delivery of data within an Ethernet network. For network convergence, UAFX will follow IEC/IEEE 60802 TSN Profile for Industrial Automation (see 6.3).

When layered over Ethernet-APL, UAFX provides an intrinsically safe communications solution for hazardous zones and divisions. Furthermore, functionally safe communications using PubSub, and eventually Client Server, can be addressed by adding the OPC UA Safety protocol (see OPC 10000-15). Authenticated and encrypted Connections and Client Server messages provide Cyber Security protection using standard OPC UA security mechanisms (see OPC 10000-2).