Fieldbus rivals chat via Ethernet

The recent Hanover Fair witnessed the first public demonstration of a technology that allows plant data to be exchanged between different fieldbus and automation systems, via Ethernet. The multi-vendor demonstration of the OPC DX (OLE for Process Control Data eXchange) technology included four systems inter-operating across an Ethernet network using Ethernet/IP, Profinet, Foundation Fieldbus HSE (High Speed Ethernet) and Interbus.

The main aim of OPC DX is to cut the costs of integrating systems by allowing a wide range of fieldbus and automation systems from different suppliers to inter-operate with each other. It also allows all of the equipment to be configured using open, supplier-independent software tools.

Equipment for the demonstration was provided by Rockwell Automation, Siemens, Phoenix Contact, and Fisher Rosemount. The demonstration was organised jointly by the OPC Foundation, Profibus International, the Open DeviceNet Vendors Association, Controlnet International, the Fieldbus Foundation, and the Interbus Club.

For the demonstration, Rockwell embedded a DX server into one of its Allen-Bradley ControlLogix PLC modules. The company also showed a software product that combines a vendor-independent OPC DX configuration tool with a DX server similar to that in the PLC.

"What makes OPC DX unique is the configuration tools," says Rich Ryan, president of Rockwell Software. "The ability for a single tool to configure all of the OPC DX devices on a network, no matter what manufacturer they come from, and using standard DCM and XML based interfaces to do it, opens a whole new market for software tools."

The OPC DX standard builds on the existing OPC DA (Data Access) standard which provides vertical integration between shopfloor devices and supervisory systems. OPC DX adds horizontal peer-to-peer data exchange, as well as vertical communications between different fieldbuses and automation systems incorporating an OPC DX server.

The final specification and code for the OPC DX standard, which also defines the configuration interface, is due to be published this month.