Prototype of the Ethernet APL switch with the connected sensor

Simple Ethernet connection of sensors by means of the APL field switch

What exactly is Ethernet APL?

The abbreviation APL stands for Advanced Physical Layer and describes a further development of physical data transmission in Ethernet networks. This physical layer makes it possible to exchange Ethernet data via only two wires, instead of the previously required four or eight wires.

Aside from pure communication, the technology also optionally enables the supply of power to connected devices on the same pair of wires.

Ethernet APL therefore is one of several manifestations of the Single Pair Ethernet (SPE) and enables the direct connection of sensors, thereby making possible a continuous communication to the last few meters in the field.

What is the difference between SPE and Ethernet APL?

The Single Pair Ethernet technology is comprised of various standards which support different data rates and cable lengths and which therefore are suitable for various applications. A distinction is made between the standards 10BASE-T1S, 10BASE-T1L, 100BASE-T1, and 1000BASE-T1.

Comparison of the data rates and cable lengths of the different Ethernet standards

Advanced Physical Layer uses the 10BASE-T1-L standard of the IEEE 802.3cg along with the IEC TS 60079-47, 2021-03 (2-WISE) standard (2-WISE = 2-Wire Intrinsically Safe Ethernet), and supports explosion protection methods including intrinsic safety. Thus Ethernet APL enables use in potentially explosive areas and the bridging of great distances up to 1,000 m at 10 Mbps.

Ethernet APL features

The APL technology offers the following features:

  • Bridging large distances: Trunk lengths of up to 1,000 m, spurs up to 200 m
  • Use in explosion-protected areas is possible (zones 0, 1, and 2)
  • Interoperability of the devices and systems of different manufacturers
  • Capture and analysis of huge amounts of additional data is possible (big data) – new solutions such as predictive maintenance can be realized to increase availability
  • Cost-efficient modernization of systems with existing cabling and proven Ethernet protocols such as EtherNet/IP™, HART IP, OPC UA, and PROFINET
Figure of a processing plant and an indicated Ethernet APL network

Ethernet APL in processing plants

Where is Ethernet APL used?

Advanced Physical Layer enables the direct connection of devices and sensors in the Ex areas of process technology applications. Due to the direct Ethernet integration, complex gateway solutions can be dispensed with if data is to be accessed from the field. Therefore, Ethernet APL is the economic basis, and an empowering factor, for the IIoT in process automation. At the same time, it enables new concepts, such as the NAMUR Open Architecture (NOA) or the Open Process Automation standard (O-PAS™). Consequently, different user groups can benefit from this new technology:

  • Operators and users
  • Control system suppliers
  • EPCs and system integrators
  • Device manufacturers

Setup of an APL network

Ethernet APL can be used both in compact plants (e.g., pharmaceutical or chemical plants) and in extensive plants in the process industry. The trunk and spur topology is used for greater range.

The Ethernet APL switches installed in the field are intended for use in potentially explosive areas (zones 1 and 2 or division 2), so that all increased demands regarding explosion protection can be met with the degrees of protection of increased safety or intrinsic safety.

Setup of an APL network for extensive plants in the process industry
Power switch
Ethernet APL is connected to the top level of the control cabinet by means of the power switch. It feeds power and data communication into one or more trunk ports. To do this, the power switch is supplied with voltage externally.
Trunk cables
The trunk cables are rated for high power loads to supply devices and for greater cable lengths of up to 1,000 m between APL field switches in zone 1.
Field switch
The field switch has APL spur ports to which the field devices and instruments are connected. It can be supplied with electrical current via an Ethernet APL cable (trunk) or externally.
Field devices
The field switch can be used to distribute both communication signals and energy to the field devices via the spurs.
Spur cables
The spur cables have a lower power rating with optional intrinsic safety for lengths of up to 200 m in zone 0.

In addition, the network topology can be flexibly designed so that even compact layouts can be realized. It is possible to dispense with the trunk by using the APL switches to connect the APL spur ports directly to the standard Ethernet.

Structure of an APL network for compact systems
Field switch
The field switch has APL spur ports to which the field devices and instruments are connected. It can be supplied with electrical current via an Ethernet APL cable (trunk) or externally.
Spur cables
The spur cables have a lower power rating with optional intrinsic safety for lengths of up to 200 m in zone 0.
Field devices
The field switch can be used to distribute both communication signals and energy to the field devices via the spurs.
Ethernet APL logo

Ethernet APL project logo

Our commitment to Ethernet APL

Within the scope of the Ethernet APL project, Phoenix Contact and other leading suppliers of process technology are working on the realization of a two-wire Ethernet solution that meets user demands. Together with the standardization organizations PROFIBUS & PROFINET International, FieldComm Group, ODVA, and OPC Foundation, the industrial partners are establishing an open standard based on a new physical layer for use in process automation.

Phoenix Contact presented the first working prototypes of Ethernet APL switches in demonstrators during the NAMUR General Meeting in late 2019 and the ARC Forum in February 2020. The NAMUR installation with the APL project partners ABB, Endress+Hauser, KROHNE, and SAMSON used the PROFINET protocol to connect data via the Ethernet APL switch and PLCnext Technology to an HMI and the Cloud. At the ARC Forum, we were able, together with ABB, to demonstrate the connection via OPC UA.

Further new communication technologies Consistent communication through to the field

New communication standards such as OPC UA, TSN, SPE, and 5G are currently being created by various committees and in standardization projects. These new technologies, however, are not to be considered independent of each other – rather, they will form the communication of the future together.
As a technology leader with more than 30 years of experience in industrial communication technology, Phoenix Contact is actively involved in all of the key standardization committees. In these committees, we are helping to shape the new, cross-manufacturer communication standard for automation for you.

Find out more about the new standards on our webpages.