Two previous blogs in this series have discussed the client-server structure of OPC Unified Architecture (UA) and the use of objects and information models in OPC UA. Now we turn to another OPC UA advantage – the aggregation server.
The System of SystemsThe platform independence and scalability of OPC UA make it a critical technology for the industrial internet. An intelligent device with an embedded OPC UA server and client can achieve bi-directional communication with other intelligent devices. An aggregation server can concentrate, normalize, and enrich information from underlying servers and then make that aggregated information available to high-level clients as shown in Figure 1. The aggregation server plays an important role in minimizing the number of connections that resource-limited devices need to manage. The various systems that comprise the industrial internet will run on a variety of operating systems; an OPC UA aggregation server might run on Windows whereas an OPC UA embedded server might run on VxWorks. The ability of OPC UA to provide secure data exchange independent of platform and operating system is essential to converge disparate systems into one secure system. The resulting chain of systems, from low-level devices to SCADA systems to enterprise applications, are integrated with OPC UA to form a system of systems.
The aggregation server allows the OPC UA backbone to scale at the enterprise level. It allows the multiple assets, each providing its own information, to be aggregated centrally and normalizes the data to make that information available to higher level clients. These higher level clients can be OT clients such as HMI, SCADA, MES systems, etc., but more importantly, they can be IT and cloud apps. This makes the aggregation server truly a founding of Edge controls as now the IT, OT and cloud apps can act upon the same source of data coming from the machines directly to them over the OPC UA backbone.
The next blog is the final one in this series and addresses the critical issue of inner and outer loop control.