Integrating Ethernet-APL into Process Instruments

  • Post category:TECH TIPS
  • Reading time:4 mins read

PROFINET over 10BASE-T1L use-cases, including Ethernet-APL, continue to expand across process and factory automation driven by the requirement to connect more field devices to PROFINET networks. With more field devices connected, richer datasets are made available to the higher-level management systems, leading to significant productivity increases while reducing operating costs and energy consumption.

The vision of Ethernet to the field is to connect all sensors and actuators to a converged IT/OT network. To achieve this vision, there are system engineering challenges, as some of these sensors are limited in power and space. There is a growing market of low power and ultra-low power microcontrollers with significant internal memory capabilities for sensor and actuator applications. But most of these processors have one thing in common – NO integrated Ethernet MAC. They don’t support an MII, RMII, or RGMII media-independent (Ethernet) interface. A traditional PHY cannot be connected to these processors.

To connect an increased number of lower power field devices, a 10BASE-T1L MAC+PHY is required to enable long reach PROFINET field device connectivity. With a 10BASE-T1L MAC-PHY, Ethernet connectivity to a processor is made via SPI, reducing the burden on the processor and removing the need for an integrated MAC. The MAC functionality is now integrated directly with the 10BASE-T1L PHY. A 10BASE-T1L MAC-PHY provides device architects increased flexibility and choice by enabling a variety of ultra-low power processors. By optimizing the application partitioning, a 10BASE-T1L MAC-PHY enables lower power field devices, for Zone 0 intrinsically safe deployment in the process industry referred to as Ethernet-APL.


Both a 10BASE-T1L PHY and a 10BASE-T1L MAC-PHY bring significant advantages in different use-cases. For power critical applications, a 10BASE-T1L MAC-PHY enables lower system power by providing more flexibility on the choice of the host processor to include ultra-low power processors that do not have an integrated MAC. When upgrading an existing device to add Ethernet connectivity, a 10BASE-T1L MAC-PHY provides a route to reuse the existing processor and adding Ethernet connectivity via an SPI port, removing the requirement a move to a larger processor with an integrated MAC.

For high-performance applications where a field device requires a high-performance processor that has an integrated MAC. A 10BASE-T1L PHY with MII, RMII, and RGMII MAC interfaces allows a 10BASE-T1L PHY to be quickly developed by reusing existing MAC interface drivers to add PROFINET connectivity.

Increased Flexibility

With the availability of both 10BASE-T1L PHYs and 10BASE-T1L MAC-PHYs, network architects now have increased flexibility to meet the requirements of tomorrow’s Ethernet-connected manufacturing installations. Ultra-low power devices and high-performance devices can be deployed on the same Ethernet network and comply with strict maximum power limitation for hazardous area use-case requirements. 10BASE-T1L Power Switches and 10BASE-T1L Field Switches require robust, low power 10BASE-T1L PHYs to be used with PROFINET Industrial Ethernet Switches to deploy Trunk and Spur network topologies that provide both power and data over a single twisted pair cable, including hazardous areas use-cases.

PROFINET field device connectivity requires both 10BASE-T1L PHYs and 10BASE-T1L MAC-PHYs to connect a wide range of field devices. Higher power field devices, including flowmeters, will use a high-performance processor with an integrated MAC with a 10BASE-T1L PHY. Lower power field devices, including temperature sensors with an ultra-low power processor that does not have an integrated MAC, will use a 10BASE-T1L MAC-PHY for PROFINET connectivity via an SPI interface to the processor.

Maurice O’ Brien
Strategic Marketing Manager
Industrial Communications
Analog Devices

Volker Goller
System Applications Engineer
Deterministic Ethernet Technology
Analog Devices