An essential feature of modern Industry 4.0 solutions is the networking of machines and plants. If a continuous digital data flow is guaranteed across all production levels, data from intelligent field devices can provide well-founded information on the plant status. In this way unplanned outages can be avoided, downtimes reduces and maintenance costs lowered. How does this work in the ideal case?
How to ensure a continuous digital data flow
Ideally, asset, diagnostic and process data from field devices are stored in real time and are transferred directly from the field to the tablet. Maintenance personnel therefore has a clear and comprehensive overview of aggregated information at all times, and can use this to make informed decisions that speed up troubleshooting. This would be the ideal scenario. But for it to be realized:
Integration technologies for digital communication
Today, users can choose from several integration technologies, each of which has adopted a different approach:
All of these technologies are based on the traditional automation pyramid and are not transparent at all levels. The data is collected from field devices via fieldbus or HART and converted in the SCADA level for use by applications. These technologies are based on software products that must always be installed on terminal equipment in order to establish a connection. There is no provision for further machine processing of the data.
Extending the traditional automation structure with Namur Open Architecture
The conventional automation pyramid has proven itself over many years and offers a high level of operational reliability. However, it offers too little flexibility for the implementation of new technologies in the context of Industry 4.0 solutions. Therefore Namur (the “User Association of Automation Technology in Process Industries”) has extended the existing structure with the NOA concept (Namur Open Architecture) by an open OPC UA interface. The Namur Open Architecture (NOA) describes how to export data to the system via an open OPC UA interface from the existing automation world for monitoring and optimization purposes, leaving core automation tasks largely unaffected. Alternatively, a second communication channel can directly access information from existing field devices.
Against this background, HART-IP as a further open interface is increasingly coming into the focus of users and system providers. The HART-IP protocol has been part of the FieldComm Group’s HCF Network Management Specification since June 2012. It enables plant-wide, large scale solutions and offers a high degree of interoperability between devices and applications. The protocol runs over IP-based networks such as Ethernet and Wi-Fi and works over UDP and TCP with IPv4 or IPv6. The HART IP application layer is based on the same commands as the 4 to 20 mA HART protocol.
Implementing the Namur Open Architecture
In implementing the NOA concept, devices provide the open, OPC UA-based NOA interface at various levels of the automation structure. Using an embedded OPC UA server, the NOA information model can be implemented by a remote I/O system, for example, a gateway or, in the future, directly by field devices with an Ethernet connection. The NOA diode ensures secure read-only access to the data.
With its smartLink DP, Softing offers a NOA-compliant gateway that collects data from HART devices via PROFIBUS remote I/Os and makes it available via OPC UA in accordance with the companion specification. In connection with a dataFEED secure integration server, which delivers the data unilaterally to the outside world, Softing already offers the functionality of a NOA diode. Moreover, a HART-IP server integrated into the smartLink DP provides transparent access to HART field devices via Ethernet. In the future, it will be possible to use any HART-IP client, such as Emerson's AMS Device Manager or ProComSol's Android app DevComDroid, to parameterize, monitor and evaluate HART field devices via this open communication standard. The smartLink DP Gateway is scheduled for release in April 2020.