What are the benefits to the control engineer of moving intelligence to the edge?

Operators and vendors alike expect to gain insight into the status of process equipment and the process plant to achieve high output quality while maintaining safety standards to protect people, the plant and the environment. Insights can help reduce energy costs while meeting production demands through monitoring and optimization.

Intelligence at the edge of process plants, i.e., in smart sensors and actuators, has been available for some time. Processing power enables multivariable instruments. This results in lower capital costs for the instrument, including attributable costs and effort for engineering, piping, fittings, and even spare parts inventory. Valve position sensors can report breakaway and run times, allowing maintenance teams to take a predictive approach to plant maintenance, leading to lower operational costs. Valves with FOUNDATION Fieldbus H1 interface can run a PID algorithm locally based on input from flow or level measurement on the same segment in the field. However, this intelligence is only used to a limited extent today – partly due to limited bandwidth and the lack of flat network technology.

At a glance

• Intelligence already exists at the edge, i.e., in the field of process plants
• Access to this intelligence is costly, so it remains “locked in” in the instrument.
• Latest developments in technology allows users to harness this intelligence
• Ethernet-APL enables a fast and flat network infrastructure in the field
• Technology provides seamless access to remote I/O

Ethernet-based industrial protocols and infrastructure enable flat networks and open architectures. However, it is only recently that these technologies have the features required for process automation that now enable intelligence to be deployed at the edge of process plants.

As of today, an Ethernet-based, flat network can be deployed in the field within process plants. The Ethernet Advanced Physical Layer, or Ethernet-APL for short, is a robust physical layer which carries power and communication on two wires. It is an open and complete set of standards available to any vendor or user, providing high bandwidth, long cable lengths, and explosion protection with built-in intrinsic safety. Because it is only a physical layer, Ethernet-APL can carry all Ethernet-based protocols.

Industrial protocols now offer “profiles” for simple engineering, such as a standardized description of device types independent of make, type and manufacturer; controllers can be reconfigured “in run” for continuous operation. Profile-based communication, e.g., with PROFIBUS PA or PROFINET, enables operation and device replacement as simple as users know it from 4-20 mA – and even eliminates the need for PV scaling.

With this combination of technologies, users can now take advantage of data that was previously unavailable. While the controller and device maintain their cyclic data exchange, an asset management system can log historical data or store configuration settings via HART-IP or OPC UA protocols. At the same time, a maintenance worker can access a device’s website via a smartphone to retrieve status information. Open communication via Ethernet-based physical layer and protocols provides operators and maintenance teams with application and handling advantages that were much more difficult to achieve with the existing technology portfolio.

Brownfield Plants

And how could this task be solved in brownfield plants with existing legacy control equipment (and at what cost)?

For brownfield upgrades, a significant benefit lies in protection of the investment in existing assets while at the same time upgrading communications to the controller via Ethernet. This enables or improves access to data currently “locked in” the instrumentation. The cost is the same as a typical brownfield system upgrade.

Ruggedized remote I/O systems such as Pepperl+Fuchs’ LB/FB remote I/O systems, installed in the field, connect to the same backbone and provide access to modern instruments with 4-20 mA interfaces. They require an external power supply and a standard or fiber optic Ethernet connection back to the control room. In addition to the primary reading, the remote I/O station can translate status and diagnostic data, secondary readings or historical data traces from HART to the Ethernet-based protocol of choice. This access is as fast as it can get, as the remote I/O uses individual HART masters per instrument, eliminating bus cycle times.

For PROFIBUS PA instrumentation, the new Ethernet-APL rail field switch from FieldConnex offers dual-purpose spur/instrument ports. This option automatically detects and adapts to PROFIBUS PA or PROFINET over APL communication. A single infrastructure can connect and operate both generations of communication technologies simultaneously, saving significant investment costs for instrumentation and infrastructure. Even minor upgrades are possible when the value of high-speed, Ethernet-based communication is required, such as for certain mission-critical sensors or actuators. Ethernet-APL field switches can be installed in junction boxes near instrumentation and can share the same communication and power connection as remote I/Os.

For new plants being built today, engineers should consider Ethernet-APL as the main infrastructure. This provides a future-proof infrastructure with access to all device types and technologies that can be upgraded at any time.

Ethernet-based communication via standardized protocols such as PROFINET, EtherNet I/P, OPC UA and HART-IP enables access to intelligence that is already at the edge using the sensors and actuators installed in plants today. Users can leverage this data from any process plant and without constraints to improve the efficiency of standard operating procedures and move from reactive to predictive and proactive plant maintenance, monitoring and optimization.

Gerriet Lohmann and Andreas Hennecke, Pepperl+Fuchs