Skip to main content


Ethernet-APL is an enhanced physical layer for single-pair Ethernet (SPE) based on 10BASET1L. It communicates via a cable length of up to 1000 m at 10 MBit/s, full-duplex, which is more than 300 times faster than current technologies, such as HART or fieldbus. It is the logical extension for Ethernet and provides the attributes required for reliable operation in the field of a process plant. Ethernet-APL is a physical layer that will be able to support any higher-level Ethernet protocol including PROFINET.

Ethernet APL enables PROFINET to the Field of Process Plants

Ethernet is the de-facto communication standard in enterprises, but it does not meet process automation without modification. Ethernet with an Advanced Physical Layer (Ethernet-APL) will enable long cable lengths and explosion protection via intrinsic safety with communication and power over two wires.

Based on IEEE and IEC standards, Ethernet-APL supports PROFINET and any other Ethernet-based automation protocol and will develop into a single, long-term stable technology for the entire process automation community. Process plants operate for 20+ years and are required to be safe for people, the product, and the environment. Explosion potential in hazardous areas and harsh conditions require that any deployment of new technology is both thoroughly tested and provides added business benefits. Technology must not be overly complicated or require extensive training.

The agreement to develop the Ethernet-APL technology under The APL Project” was established in 2018 and is backed by the leading industry standard development organizations (SDOs), FieldComm Group, ODVA, OPC Foundation, and the project host PROFIBUS & PROFINET International as well as by major industry suppliers of process automation, including ABB, Emerson, Endress+Hauser, Krohne, Pepperl+Fuchs, Phoenix Contact, R. Stahl, Rockwell Automation, Samson, Siemens, Vega and Yokogawa

What makes Ethernet-APL unique

Ethernet-APL is designed to support various installation topologies, with optional redundancy or resiliency concepts and trunk-and-spur. Ethernet-APL explicitly specifies point-to-point connectionsonly with each connection between communications partners constituting a “segment”.

Find out more details in the Ethernet-APL White Paper.

MinutePROFINET: APL [Advanced Physical Layer] for Industrial Ethernet - Intrinsically Safe Ethernet

On 'Play' external media is loaded and YouTube sends you some cookies!

The Value Added to PROFINET by Ethernet-APL

Knowing the key advantages of PROFINET and it’s well known broad industrial acceptance for reliable, high- performance communication in any automation domain combined with the new physical communication layer creates new value for the process automation like

1Two-wire cable
2Long cable runs
3Power and communication on the same cable
4Support of all explosion protection techniques incl. intrinsic safety
5Simple installation technology
6Reuse of existing fieldbus cable type ‘A’, which reduces cost and provides
7easy migration strategies from fieldbus PROFIBUS PA to PROFINET over APL
8Resilience to electro-magnetic interference
9Support of surge protection

Process Automation networks with PROFINET

How PROFINET over APL differs from classic Ethernet connectivity

Ethernet-APL is an enhanced physical layer for single-pair Ethernet (SPE) based on 10BASE-T1L, as shown in the figure below.

It communicates via a cable length of up to 1000 m at 10 MBit/s, full-duplex, which is more than 300 times faster than current technologies, such as HART communication. It is the logical extension for Ethernet, that provides the attributes required for reliable operation in the field of a process plant. Ethernet-APL is a physical layer that will also support OPC-UA or any other higher-level protocol.

PROFINET over APL includes additional attributes required by process applications. These features derive from the requirements of outdoor installations and hazardous area protection. They follow respective IEC standards and provide interoperability and simplicity, for example:


  • 2-WISE stands for 2-Wire Intrinsically Safe Ethernet. This IEC technical specification, IEC TS 60079-47 (2-WISE) defines intrinsic safety protection for all hazardous Zones and Divisions. For users, this includes simple steps for verification of intrinsic safety without complex calculations.
  • Ethernet-APL defines port profiles for multiple power levels with and without hazardous area protection.
  • PROFINET over APL allows wiring to screw-type or spring-clamp terminals, thus supporting cable entry through glands. Additionally, well-defined connector technology ensures simplicity during installation.

What can PROFINET over APL be used for?

PROFINET over APL is designed to support all known installation/network topologies, with optional physical redundancy, scalability and dynamic reconfiguration. It utilizes the trunk/spur methodology already familiar from PROFIBUS PA.


As defined by Ethernet-APL technology, there are two general types of network segment concepts:


1. The "Trunk" provides high power and signal levels for long cable lengths of up to 1000 m.

2. The "Spur" carries lower power with optional intrinsic safety for lengths of up to 200 m.


For building any network topology currently two types of switches are defined:


1. The power switch feeds power and communication into one or more trunk ports. It is typically externally powered.

2. The field switch provides at least one port to which a spur can be connected. It can be powered via the trunk or externally.

This allows for the creation of the typologies as shown in the figure (for example):

Going into more to detail, the following technical data is defined to be the key features of Ethernet-APL, so also by PROFINET over APL:

Here you can find several frequently asked questions:

Knowing that communication technology in process automation improved over decades, there are many different ones established which are not directly comparable and they all have their own unique characteristic.

However, comparing the basic communication (length, speed, cable type, etc.) and network aspects can be measured to get a rough indication:


Definitely yes, because PROFINET is a media-independent Ethernet-based technology. PROFINET uses classic copper CAT-cables, fiber optic cables, WLAN, and therefore Ethernet-APL which can be viewed as just another media. In this way, all the features and advantages making PROFINET a leading communication technology are available on the Ethernet-APL media (physical layer).

Regarding the fact that PROFINET over APL uses a 10 Mbit/s communication speed, a bridging device, like a switch or converter is needed to interconnect the electrically different media of 100BASE-TX and 10BASE-T1L.

From the user point of view and from the data exchange perspective, PROFINET behaves transparently, providing all capabilities already known from the technology. 

The project to develop Ethernet-APL has already achieved its first milestones as visible in the infographic below. Together with the release of the 10BASE-T1L specification in IEEE, the progress of IEC specifications for 2-Wire Intrinsically Safe Ethernet (2-WISE) and power port profiles is on track.

Final PHY chips will be available in early 2021, so the first field devices and infrastructure components are expected to be available in 2021 as well. For the installation of an Ethernet-APL system, an Engineering Guideline will be available in time.

A first pilot project with Ethernet-APL prototypes in Germany proved the working principle and the benefits of the technology. The installation of 2-wire Ethernet field devices, both actuators and sensors for all kinds of measuring types, prove the simplicity of field device installation, integration into the process automation systems, and parallel access to data from field devices.

Yes, they will. Devices created for PROFINET must meet the certification criteria defined by PI and testing for PROFINET over APL devices will be no different.

In general, PROFINET is well known for its flexibility, resilience and availability in factory and process automation. Using it over Ethernet-APL allows users to digitalize all of their automation assets leveraging the full-blown connectivity provided by an Ethernet network.

This leads to the fulfillment of user expectations of a new technology that it:   

  • extends easily into existing plants;
  • enables transparency and open, parallel access to proven-in-use field instrumentation;
  • ensures interoperability based on a single network;
  • provides standardized and well-accepted procedures for explosion hazardous areas;
  • achieves simple, flexible and vendor-independent use of all device functionality.

Furthermore, enhanced connectivity provides a powerful tool to reduce complexity in daily operation and work. The availability of a single network technology opens new business potential for both device manufacturers and plant managers based on access to data from smart instrumentation.

Ethernet-APL is a physical communication layer (media) electrically connecting two devices allowing them to exchange data on a 2-wire cable in a way like IT devices do –but with an adaptation to process automation needs.

PROFINET over APL uses this physical communication layer like it does with other cables or WLAN.

White Paper Ethernet-APL

This white paper covers the business environment, technical specifi­cations, implications for different user types, and the development status of Ethernet-APL.

Read more

PROFINET PA Basic Slide Set

This compact Slide Set PROFINET for Process Automation provides an overview why and how PROFINET is increasingly used for Process Automation.

Read more

PI White Paper: PROFINET – The Solution Platform for Process Automation

This white paper reports – oriented to the time bar of the technology development – which functions and capabilities of PROFINET are currently meeting the demands of process automation and which can be implemented and then used in products in the future based on specifications that are complete or in progress.

Read more

Process Control Devices

Plants with continuous processes especially in the chemical branch are managed by process controlled systems. The process control devices are connected to the plant network providing and consuming the measuring values respective output values primarily.

Read more

Ethernet APL and Field-device-Security

Beitrag von Feldgeräten zur Zukunft der Anlagensicherheit (OT-Security) (german version only)

M. Skuballa, A. Walz, H. Bühler, A. Sikora

Read more


The Ethernet-APL Engineering Process. A brief look at the Ethernet-APL engineering guideline.

Niemann, Karl-Heinz, atp Magazin, 9, 2021; S. 78–83
Read more (en)

Read more (de)


Impact of mixed speed networks on the performance of Ethernet real time communication protocols like PROFINET

Read more (en)


The Next Generation: Ethernet-APL for Safety Systems
Contribution for the NAMUR Annual General Meeting 2022. In atp Magazin, 01-02, 2023; S. 78–85 by Niemann, Karl-Heinz; Risser, Marc

Read more