10Base-T1S Automotive Ethernet vs. 10Base-T1L Industrial Ethernet

Figure 1: 10Base-T1S and 10Base-T1L differ primarily in
reach, encoding methods, topology and applications.

10Base-T1S, a variant of Automotive Ethernet, and 10Base-T1L, also known as Industrial Ethernet, are Single Pair Ethernet (SPE) protocols described in IEEE 802.cg standards. Both offer the same 10 Mb/s communication speed using a single, unshielded twisted pair (T1), but differ in specifics of reach, encoding schemes and topologies, as well as their principal applications.

Automotive Ethernet in the Vehicle

Figure 1 Block diagram of a typical ADAS system
showing the in-vehicle networks used.

As all Automotive Ethernet technologies utilize a single twisted-pair cable (T1) and a point-to-point network topology, they differ primarily in their data rates and encoding methods. For the most part, the data rate determines the applications for which a particular Automotive Ethernet standard can be used. If we take the case of an automatic driver assistance system (ADAS), we can see where each Automotive Ethernet variant might best be used to replace existing automotive protocols. 

(Click on any figure to enlarge the image.)

Fundamentals of Automotive Ethernet

Figure 1: Automotive Ethernet is designed to support
increasingly complex vehicle electronic systems.

When we speak of “Automotive Ethernet”, we’re referring to a group of Ethernet interfaces intended for in-vehicle use, customized to meet the needs of the automotive industry. The first Automotive Ethernet standard was defined by Broadcom in 2011 with BroadR-Reach. Since then, IEEE has released standards for 100Base-T1, 1000Base-T1, 10Base-T1S and most recently MultiGBase-T1. Together, these standards define the general technology known as Automotive Ethernet.

Probably the first question you ask is, “Why not just use standard Ethernet?” A summary of the fundamental features of Automotive Ethernet will show how much better Automotive Ethernet is than standard Ethernet at meeting the industry’s demand for a higher speed, robust, lightweight and lower cost data interface, one that can ultimately replace the many other protocols currently used throughout the vehicle.