10BASE-T1S: Ushering in a New Era of Automotive Ethernet Networking

As fully connected software-defined vehicles (SDVs) take centre stage, in-vehicle networking technologies must be continually updated to meet growing data demands while remaining cost-effective and reliable. 10BASE-T1S offers in-vehicle Ethernet a low-cost, scalable solution designed to simplify in-vehicle network (IVN) architectures while ensuring the stability of data communications. This article explores the basics of 10BASE-T1S, its unique features and how to effectively test its performance.

10BASE-T1S Highlights

10BASE-T1S, standardized in IEEE 802.3cg-2019, is a Single-Pair Ethernet (SPE) technology that enables multi-drop network topologies. Unlike point-to-point Ethernet standards, 10BASE-T1S allows multiple nodes to connect over a single twisted pair, reducing cabling complexity and system costs.

Key features of 10BASE-T1S include:

• 10 Mbps data rate, suitable for automotive sensors, actuators, and control modules.
• Differential Manchester Encoding (DME) for improved signal integrity and clock recovery.
• Support for at least 8 nodes on a shared bus.
• Multi-drop topology, eliminating the need for dedicated Ethernet switches.
• Physical Layer Collision Avoidance (PLCA) protocol, ensuring deterministic network access.
  
  

10BASE-T1S Signaling

The Differential Manchester Encoding (DME) used in 10BASE-T1S ensures a robust signal by encoding data with a guaranteed clock transition in each bit period. This improves synchronization and reduces susceptibility to electromagnetic interference (EMI), making it well-suited for automotive applications where signal reliability is crucial.

10BASE-T1S Multi-Drop Topology

Unlike traditional point-to-point Ethernet connections, 10BASE-T1S enables multiple devices to share a single twisted-pair cable. This bus-like architecture reduces the number of required connectors and cables, significantly lowering both weight and system costs.

However, implementing multi-drop networking presents challenges such as signal reflections and contention for network access, which must be carefully managed through the PLCA protocol.

Understanding PLCA Protocol

The Physical Layer Collision Avoidance (PLCA) mechanism ensures deterministic access to the shared bus by assigning time slots to each node, eliminating traditional Ethernet’s contention-based access delays. PLCA operates as follows:

1. A beacon signal initiates the cycle.
2. Nodes receive Transmit Opportunities (TOs) in a round-robin fashion.
3. If a node has data to send, it transmits immediately upon receiving a TO.
4. If no data is available, the TO is skipped, increasing efficiency.

PLCA ensures predictable latency and reduces retransmissions due to collisions, making 10BASE-T1S ideal for time-sensitive automotive applications.

How to Test 10BASE-T1S: A Case Study

Testing 10BASE-T1S networks requires a comprehensive approach to ensure reliability, signal integrity, and compliance with IEEE and OPEN Alliance standards. GRL offers state-of-the-art testing solutions tailored to 10BASE-T1S validation, including:

1. PMA (Physical Medium Attachment) Layer Testing

• Transmitter (Tx) and Receiver (Rx) tests assess signal integrity, jitter, and bit error rates.
• Stress testing with noise generators evaluates robustness against interference.

2. PCS (Physical Coding Sublayer) and PLCA Protocol Testing

• Validation of frame structure ensures compliance with PLCA timing requirements.
• Interoperability tests confirm correct operation with multi-vendor implementations.

3. Multi-Drop Network Performance Testing

• Reflection and impedance analysis detect signal integrity issues.
• Latency and throughput measurements validate real-world performance.
  
  

Advancing 10BASE-T1S Testing with GRL

As the adoption of 10BASE-T1S grows, rigorous testing becomes essential to ensure seamless integration into automotive networks. GRL provides industry-leading expertise and solutions to support engineers in validating 10BASE-T1S implementations.

Connect with GRL at the upcoming Automotive Ethernet Summit China 2025 in Shanghai (April 1-2) to learn more about our latest test services and solutions.