PLCopen and OPC Foundation combine their technologies to a platform and manufacturer-independent information and communication architecture. This mix of OPC Unified Architecture (UA) and IEC 61131-3 creates interesting options for the realization of automation structures.
Objective is to increase the reusability of controllers and visualization modules and their communication - in the long run the efficiency of the engineering process clearly increases.
As an example imagine a PLC project running on different control platforms from different suppliers which seen from the outside by a visualization tool or MES/ERP from the axis look exactly the same: The IEC 61131-3 software model with all PLC objects and their detailed descriptions are illustrated in the OPC UA namespace by the work of the common working group by OPC UA.
Today there are still many old historically grown data exchange protocols being used in various industries. They offer little possibility to transport complex data and the extensibility is very limited. OPC Unified Architecture however, offers the basis for universal, secure and reliable network communication, i.e. provides the monitoring of configurable timeouts and connecting interruptions and encrypted communication. To use this communication as standard for the IEC 61131 environment will lead in many industries to a completely new form of information exchange: If an industry has defined a specific profile e.g. a data structure or a function block, then the question of secured and efficient data exchange and the reusability of the visualization objects is already solved. With the combination of PLCopen and OPC UA, an additional level of interoperability is standardized on top of IEC61131-3.
The first step for the joined working group was the mapping of the IEC 61131-3 software model to the OPC UA information model leading to a standard way how OPC UA server-based controllers expose data structures and function blocks to OPC UA clients like HMIs.
This first step was achieved in a very short time followed by first implementations demonstrated at the SPS/IPC/Drives show 2009 in Nuremberg. Now the technical specification “OPC UA Information Model for IEC 61131-3” version 0.09.1 is published as Release for Comments till February 19, 2010. This evaluation phase will be followed by the final release expected for April 2010.
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