Ethernet-APL Simply Explained—How Parallel Communications Work

DCS PepperlFuchs Ethernet Explained 1 400

December 8, 2021

 

Ethernet Advanced Physical Layer, Ethernet-APL for short, is the physical layer for transmitting data into the field of process plants. Pepperl+Fuchs explain in simple and understandable language what exactly Ethernet-APL is, how parallel communication works today and what possible options there are to access data.

What is Ethernet-APL?

Ethernet-based protocols such as EtherNet/IP, HART-IP, OPC UA or PROFINET utilize different physical layers. This can be explained with the ISO/OSI model (Fig.1), which generically describes communication across different systems.

For wire-based communication, the physical layer, which is layer 1, defines the electrical system: cables and connectors, signal levels, power supply, and electrical explosion protection.
Layer 7 defines how bits and bytes represent data, e.g., an analog measurement value, a counter, or a digital control output. In the context of industrial protocols, technicians and engineers however often consider a protocol like FOUNDATION Fieldbus H1 or PROFIBUS PA as one function unit. For Ethernet-based protocols, we need to abandon this simplified view. Ethernet protocols run on various media. They communicate with 10 Mbit/s, 100 Mbit/s, or 1 Gbit/s speeds. They utilize fiber optics or even Wi-Fi (blue boxes in layer 1), and finally Ethernet-APL. This physical layer is fit for the rough or at least very demanding environment in the field of process plants (green box in layer 1).

DCS PepperlFuchs Ethernet Explained 2 400

What Does Parallel Communications via Ethernet Mean?

Very simple—just think about your daily life. Where are you working? From home, on the road, or in your office? Parallel communication is the standard way of life: You might be on the phone, writing an e-mail and browsing on a website on your laptop, and all at the same time. Your children may be attending school classes or playing online video games on tablets in their rooms. And the same happens in the neighbors’ houses. This is parallel communication carried via Ethernet and other physical layers such as cable or DSL.

Or consider the following analogy: Ethernet is the road, the protocols are car brands, e.g., PROFINET, OPC UA, EtherNet/IP, HTTPS, SIP, and VoIP. The road carries any vehicle. Multiple cars and trucks can ride on the same road, until there is so much traffic that there is a traffic jam. This is where network architects come into play: they take care of the appropriate design so that traffic can run properly without congestion. Basically, Pepperl+Fuchs builds the road with switches and junction boxes, and does road maintenance with physical layer diagnostics.

For the field of process automation parallel communication means that multiple systems can access data stored in the instruments simultaneously. It can be expected that planners will select the following:

DCS PepperlFuchs Ethernet Explained 4 400

  • One real-time enabled protocol for control. This choice depends on the selected control system or PLC. NAMUR recommends PROFINET or EtherNet/IP.
  • One or more protocols for other applications such as processing diagnostic messages, alarms, or configuration management.
    NAMUR recommends OPC UA. Many vendors, Pepperl+Fuchs alike, implement this protocol in their instruments.
    HART-IP: This is what we offer with Pepperl+Fuchs Remote I/O today.
    HTTPS: Surf to the instrument from your smart phone or PC. All vendors do that in their demos today.

Multiple Ways to Access Data from the Instrument

When you direct your web browser to any website, the web browser is your client and connects to the server of the website owner. With Ethernet-APL you can call the webpage of the field instrument. The device itself then hosts the HTTPS server that you interact with: you can access status and alarms, view manuals or certificates. This happens in parallel to access from the DCS or the asset management system.

Field instruments with Ethernet-APL can host these functions, depending on the vendor’s implementation of the device. Ethernet-APL opens possibilities for parallel access enabling applications that enrich and enhance the work lives of everyone working with instrumentation and automation. This will enable users to optimize their plant for the benefit of worker safety, utilization of their plant assets, output quality and yield.

 

Source

 

Related Articles



Editor’s Pick: Featured Article

Weidmüller’s u-control 2000: The Automation Controller

Weidmüller’s u-control 2000: The Automation Controller

Weidmüller’s scalable engineering software, u-control 2000, adapts individually to your requirements. And, the u-control is powerful, compact and fully compatible with Weidmüller’s I/O system u-remote. This article looks at what makes u-control the heart of your automation.

Programmable logic controllers (PLCs) are one of the main components of any automated system. A typical control system has inputs, outputs, controllers (i.e., PLCs), and some type of human interaction with the system, a human machine interface (HMI), for example.

Read More



Latest Articles

  • The Future of AI and Vision Technology in Inspection and Quality Control

    April 2, 2025 Discover the future of AI in inspection for specialized tasks to versatile solutions.  The landscape of AI and vision technology in inspection and quality control is set to transform with the development of more generalized algorithms. These advanced systems will be capable of tackling a wide range of inspection challenges, moving away… Read More…

  • Safety Relays: Why They’re Seeing a 225% Growth in Industrial Applications

    Apri 2, 2025 If you’ve walked the floor of a modern plant lately, you’ve likely noticed a shift—machines are smarter, lines are faster, and safety systems are more integrated than ever. At the heart of this evolution sits an unsung hero: the safety relay. Once seen as a check-the-box component for regulatory compliance, safety relays are… Read More…