top of page


Word in the process control industry is spreading about a new physical layer that supports
Ethernet communication and power transmission over a single twisted shielded pair cable. This
new physical layer is dubbed the Advanced Physical Layer, APL.


IEEE recently created a new Ethernet standard, IEEE 802.3cg, defining a new variant. The new variant is
sometimes referred to as Single Pair Ethernet, SPE. There are two sub-variants of this new Ethernet

10BASE-T1S This sub-variant was developed for use in automobiles or other short distance
applications to save on wiring costs. Other applications include building automation for such
things as elevators, HVAC, and lighting. It supports a multi-drop architecture (multiple devices
on a single cable).

10BASE-T1L (APL) This sub-variant was developed for longer distance communication
needs (up to 1 km) such as in continuous process control of refineries and chemical processing
plants. It supports a point-to-point architecture (each cable has only 2 devices). It is also
referred to as APL (Advanced Physical Layer).

See the following Application Notes for more detailed information (more to come!):

Application Notes:

This application note introduces a new method of getting Ethernet to field devices.  The long distance version is targeted at the process industry.

Various Industrial Process Control networking types are compared to APL in this Tech note.

A list of URL links to specifications, papers, and standards related to APL are contained in this Tech note.

Every technology comes with its own list of acronyms and definitions.  This application note provides an explanation for these APL specific terms.

This Tech note provides information on how signaling works for APL to result in 10 Megabit per second throughput.

Any technology comes with a list of pros and cons.  This paper discusses what is currently known about the strengths and weaknesses of APL.

bottom of page