The fourth industrial revolution intended to create “smart” plants and factories focuses on communications as implied in the German Reference Architecture Model for Industrie 4.0 (RAMI4.0). As the industrial automation sector makes strides towards achieving the “Connected World”, leading industry organizations are joining forces to leverage their respective technological strengths.
Since 2011, the FDT Group and OPC Foundation have worked together on a technology initiative to provide greater access to critical information throughout the industrial enterprise. OPC provides a uniform interface for many different client applications, whereas FDT® provides network/device configuration and access to devices.
Together, FDT and OPC technologies simplify the transition to the next generation of connectivity for industrial facilities. Defined by an FDT-OPC UA device information model, the recently announced FDT/OPC Annex enhances the configuration of networks and devices, and gives the enterprise access to data without the complexity of protocol-specific handling.
History of collaboration
Technical collaboration between the FDT Group and OPC Foundation has been aimed at ensuring seamless online data exchange between automation systems, asset management systems, and other plant and enterprise systems and applications. As a result of this effort, automation end users will be able to utilize data and information models for the applications and devices supported by FDT and deploy OPC UA information modelling and corresponding services for robust application-to-device integration.
Figure 1 shows a simplified illustration of the two technologies arranged in the RAMI4.0 model. The provision of an OPC UA interface allows access to the device data from higher-level systems.
With release of the FDT/OPC Annex, sensor-to-cloud, enterprise-wide connectivity is granted with seamless data communications. The objective is a fully enabled Industrial Internet of Things (IIoT) architecture supporting mobility, on-the-wire security, and comprehensive interoperability. This solution will also be platform-independent and deployable in standalone, client/server or cloud architectures.
Working group uses cases
A joint working group of the FDT Group and OPC Foundation was established to determine the FDT/OPC UA interface specifications. This project envisioned a standard plug-in for the latest version of the FDT standard that would provide the necessary connectivity to enable data to be communicated throughout the enterprise using the OPC UA standard.
The following use cases have been defined for this purpose:
- Access to topology information
- Provision of device identification data
- Reading of device data (parameters and attributes)
- Access to device status
- Evaluation of device diagnostics
The respective FDT and OPC models provide the starting point for the specification. For FDT, information is provided by a Device Type Manager™ (DTM™). In addition to information about the DTM and device, device and process data are also described. The DTM’s "Function Info" describes the features offered for the device (e.g., for configuration and diagnostics/maintenance). There may also be references to the device documentation such as manuals, certificates or device descriptions (See Fig. 2).
The "OPC UA for Devices" specification is the starting point for the OPC UA information model. This is an additional specification based on the basic OPC UA specifications like extension of base objects. It defines the device model, describing the device communication model and the model for device integration into a host.
The device model identifies the objects for a device. This includes device parameters, callable methods, information for device identification, supported communication protocols, etc. The device communication model specifies the objects required to describe a communication topology. These are the network (protocol type) and connection point (between device connection and network, network address) objects. The model for host integration describes the components that can be accessed in a server (host). The host has access to the automation system via any type of communication. An FDT-enabled system (e.g., PLC, DCS, asset management application, standalone engineering applications) is an example of such a host.
After identifying the corresponding objects in various models, the FDT/OPC working group prepared an illustration of the FDT information for the OPC UA objects. In some places, the device model has been expanded with OPC UA to take account of specific FDT information.
Once the specification was completed, prototyping was performed to check the defined use case models. The first step involved using a UA modelling tool to specify and test the data types. In the second step, an OPC UA server was implemented with FDT integration. A client was also created for the test. Figure 3 shows the architecture of the system.
The OPC UA server is part of the FDT/FRAME™-enabled system application. The information model for the OPC UA server is generated automatically within the FDT/FRAME Application data. The server can be accessed with any OPC UA client via a secure connection. The client is flexible and versatile, and can be integrated in other systems or run on a mobile device, depending on the intended application.
Summary and outlook
The strength and versatility built into the open FDT standard allows for backwards and forward adaption of technologies as they evolve to fit future automation needs across the process, hybrid and factory market spaces. FDT is the solution, unmatched in the industry today, offering a single system solution for device management for all communication protocols and networks, and allowing access to devices via ”tunnelling” throughout the bus hierarchies. Uniting FDT and OPC provides the ideal bridge to systems that demand data from these devices and opens the door to Industrie 4.0.
With release of the FDT/OPC UA Annex this month, the FDT Group has taken an important step forward towards helping industrial end users realize the promise of IIoT and Industrie 4.0 “Connecting the World.” Indeed, it is opening the door to enterprise-wide, sensor-to-cloud interoperability and enhanced lifecycle management throughout the industrial sector
This article is part 7 of an 8 part series discussing FDT in Factory Automation. Below are the links to review the other published articles.
Article 7 - With FDT and OPC UA Towards Industrie 4.0
Article 8 – Look for the final article, Engineering, Configuration and Diagnosis of the Industrial Internet of Things with FDT in the next issue of Device Integration Strategies.