IEEE Approves '10BASE-T1L PHY' Standard in '19
Between devices up to 1 km apart via PoDL
Support for power and data transmission and reception, increasing the number of applications


As smart factories become more widespread, efforts are being made to achieve factory autonomy beyond factory automation. In addition, as the COVID-19 pandemic prolongs, the non-face-to-face trend is strengthening across society, and the number of companies seeking to introduce remote solutions is also increasing.

In order to properly introduce autonomous systems and remote solutions, it is essential to build a communication infrastructure that reliably transmits large amounts of data. Recently, wireless communication solutions, led by 5G, have been receiving a lot of attention, but wired communication solutions, which are still evaluated well in terms of reliability, are being adopted more. Ethernet is one of them.

However, due to its relatively short communication distance (200 m), Ethernet’s use in the industry was limited to process automation within factories. Then, in November 2019, the trend changed when IEEE approved the 10BASE-T1L Ethernet PHY standard.

We met with Kim Ryeong-mo, deputy manager in charge of broad market application technology support at Analog Devices Korea (ADI), and asked him about the changes that the 10BASE-T1L standard will bring to the industry in the future.


Q. How does the 10BASE-T1L Ethernet PHY standard, approved in November 2019, improve upon existing Ethernet PHY standards?
A. There are improvements in three areas. First, the ability to detect link losses of less than 10 μs in real-time industrial Ethernet protocols has been added. Second, packet detection for IEEE 1588 timestamps has been added to ensure accurate timing across the network. Third, the system-level robustness has been improved at power-on through an on-chip power supply monitor.


Q. The 10BASE-T1 standard is for automotive use, so why is 10BASE-T1L suitable for industrial use? Is it just a similar name?
A. 100BASE-T1 is a 100 Mbps automotive Ethernet standard to increase data throughput in in-vehicle infotainment (IVI), ADAS, powertrain, and other electrical systems, meet stringent automotive emission standards, and reduce cabling weight and cost.

On the other hand, 10BASE-T1L can reuse some of the existing installed Ethernet cables and can upgrade brown field process automation installations using Ethernet-APL (Advanced Physical Layer) based on the 10BASE-T1L physical layer. In addition, it provides high data rates, ease of use, and interoperability in the field.

For example, it supports two amplitude modes: using 2.4 V peak to extend the communication distance of a point-to-point communication support solution up to 1 km, or using 1.0 V peak for shorter distances. The 1.0 V peak amplitude mode allows application in explosion-proof system (Ex) environments and meets demanding maximum energy limits.


Q. 10BASE-T1L is a single-pair Ethernet standard. What is the difference between single-pair Ethernet and 2-pair and 4-pair Ethernet?
A. 10BASE-T1L is a technology that simultaneously transmits power and data over long distances using a single shielded twisted pair cable using two-wire technology. It has four differences compared to 2/4-pair Ethernet. First is the transmission speed. 2/4-pair Ethernet can transmit up to Gb, but 10BASE-T1L is a 10Mb dedicated line.

Second is the data transmission distance. 2/4 pair Ethernet supports up to 100m, and 10BASE-T1L supports up to 1km. Third is the connector type. 2/4 pair Ethernet uses RJ45, but 10BASE-T1L uses a 2-pin connector. Fourth is the power transmission part. 2/4 pair Ethernet uses PoE (Power over Ethernet) to transmit power and data, and 10BASE-T1L uses PoDL (Power over Data Line).



The 10BASE-T1L standard provides seamless edge-to-cloud connectivity for process automation systems, thereby supporting the creation of rich data sets for advanced data analytics.



Q. What is the correlation between the introduction of a 10BASE-T1L solution and the presence or absence of a gateway installation? Why does it reduce the need for gateway installation?
A. The 10BASE-T1L solution integrates Ethernet as a communication method at the enterprise, control, and field levels in process automation, reducing the need for complex and power-hungry gateways.

Gateway savings translate into reduced gateway installation costs and complexity. 10BASE-T1L based converged networks offer simple installation, easy device replacement, and faster network commissioning and configuration. This results in simpler root cause analysis and maintenance in the field, as well as faster software updates.


Q. Why is 10BASE-T1L suitable for 'Zone 0' applications?
A. Zone 0 is a hazardous area where sensors or actuators for flow, level, pressure and temperature are installed. Unlike machine building or factory automation, in process automation, sensors and actuators are not located close to the controller. It is rare for a sensor to be 200 m away from an I/O, and the distance between field switches is up to 1 km.

Unlike existing Ethernet PHY standards that could only support up to 200 m, 10BASE T1L is the optimal solution for controlling ultra-low-power, high-durability field devices suitable for Zone 0 applications at distances of up to 1 km.


Q. Do you see the Ethernet PHY standard completely replacing the 4mA-20mA HART and fieldbus protocols in the long term?
A. Legacy protocols have been successfully deployed in process automation applications for years and are well-proven, robust solutions that won’t disappear overnight.

However, 10BASE-T1L can be customized at the point of installation, which has the advantage of reducing time to market, reducing design resources, and providing a universal product that can be used widely across projects and customers. New 10BASE-T1L-compliant devices are expected to coexist with existing protocol-compliant devices for some time.


Q. Why is the 10BASE-T1L solution less difficult to build?
A. Existing process automation engineers have knowledge and experience in installing, deploying, and debugging 4mA to 20mA using HART and fieldbus protocols. On the other hand, engineers who are just graduating from college are more familiar with Ethernet-based technologies. Therefore, they can build 10BASE-T1L solutions faster than legacy ones.


Q. If there is a 10BASE-T1L related solution provided by ADI, please introduce it.
A. ADI recently launched the 'ADIN1100' industrial Ethernet PHY device to support the 10BASE-T1L Ethernet PHY standard.

The device complies with 10BASE-T1L IEEE Std 802.3cg-2019™ and supports 1.0/2.4V transmission levels for Zero 0 domain. Suitable for intrinsically safe applications, the ADIN1100 provides an MII, RMII MAC interface to the host processor, with pin strapping for master/slave selection, amplitude transfer, and PHY addressing.

The low-power ADIN1100 is available in a compact 6×6 40-pin LFCSP package and operates over the –40 to 105°C temperature range.