The connection of visualization, manufacturing execution systems (MES), condition monitoring and product data acquisition via OPC to the control plane is a globally established procedure today. But this 15-year-old technology is afflicted with some disadvantages—particularly, OPC’s connection to Microsoft’s DCOM-architecture, and the fact that it doesn’t work without MS-Windows operating systems. OPC UA (unified architecture) is the remedy for these deficiencies.
In the summer of 2007, a smoothly running live demonstration was shown at a conference of the SPS MAGAZIN titled “OPC UA Goes Embedded.” Four years later, however, this technology has yet to invade users’ experience. OPC UA products still are a scarce commodity. But that situation is now about to change.
OPC UA technology has quite a lot to provide—independence of platforms, security and the information model. Since 2008 the OPC Foundation (www.opcfoundation.org) and the PLCopen (www.plcopen.org) have worked together on a specification to enable a direct information exchange among controls. The first step was the mapping of the IEC61131-3 control programming software model to the OPC UA information model.
This specification is already available. The goal is the reusability of PLC (programmable logic controller) and visualization modules through standardization. Information exchange and efficiency during engineering processes are supposed to be improved, although it should be noted that this is not real-time communication. But standardization on the controller would relieve communication between control and field levels.
Functional profit
The small footprint of OPC UA is the first to enable a direct integration from OPC to controls, panels and field devices and makes a separate Windows computer needless. The integration into field devices is much more of an opportunity. Leaders of the European branch of Siemens announced exactly that. Such products will be shown at the upcoming SPS/IPC/DRIVES show in Nuremberg this November, one of the top global events for automation technology. In addition to standardization, the integrated security architecture for communication is an interesting feature of OPC UA. In the post-Stuxnet age, this is a possible path to safe communication among several applications.
It’s obvious that suppliers of manufacturing execution system (MES) and enterprise resource planning (ERP) software are also interested in this. On May 25, 2011, an OPC UA Day was held in Germany by enterprise software vendor SAP, which saw a turnout of more than 200 attendees. The corporation itself uses an OPC UA client in its products.
At the SAP Symposium “Production in Automotive and Manufacturing Industry,” held on July 17th, Stefan Hoppe, president of OPC Foundation Europe, announced an amplified commitment concerning MES-connectivity by the association. “Interoperability in combination with safe data and information flow gains in importance, in particular as it applies to the interface between automation and MES,” Hoppe said. “The OPC Foundation will extend its successful corporation with PLCopen and harmonize MES-connectivity into the controller world. We want to work closely with other existing boards of MES standardization. This development is unstoppable.”
Talking to insiders, it now seems OPC UA is entering the practical phase. Almost all of the leading automation providers have new developments in their pipelines, some of them already highly advanced. Development projects are running at 3S, ABB, Bosch Rexroth, Mitsubishi, Phoenix Contact (KW Software), Siemens, Yokogawa and many others. An implementation from Beckhoff has also been published for a later release.
Further, porting of OPC UA stacks to Google’s Android operating system shows more potential for OPC UA. It will then be possible to access production and process data through smart phones and other Android devices without special connections or drivers.
OPC Foundation (www.opcfoundation.org)
PLCopen (www.plcopen.org)
Kai Binder, [email protected], is editorial director of SPS Magazin in Germany.
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