What is 10BASE-T1?

10BASE-T1 is based on 10Mbps communication and is standardized by IEEE 802.3cg-2019.
The 10BASE-T1 standard includes the following:

10BASE-T1S
10BASE-T1L

The features of each standard are as follows:
In this column, we will focus on 10BASE-T1S, which is intended for use in vehicles.
Details of the modulation method and communication method are explained in the Technical Column: What is MDI?

Technical column: What is MDI?

standard	Transfer speed	Modulation method	Communication method	CABLES length	Connection Method
10BASE-T1S	10Mbps	4B ⁄ 5B	PAM3	MAX:15m (P2P) Multidrop: at least up to 25m	P2P ⁄ Multidrop
10BASE-T1L	10Mbps	4B ⁄ 3T	PAM3	Max:1000m	P2P
100BASE-T1	100Mbps	4B ⁄ 3B	PAM3	Max:15m	P2P
1000BASE-T1	1000Mbps	80B / 81B	PAM3	Max:15m	P2P

What are the features of 10BASE-T1S (Multidrop)?

A major feature of 10BASE-T1S is that it supports multidrop connections in addition to the P2P (Peer to Peer) connections used in conventional Ethernet connections.
PLCA is implemented to prevent possible data collisions when connecting multidrop.
The differences between P2P and Multidrop connections are as follows:

What is PLCA (Physical Layer Collision Avoidance)?

PLCA is implemented with the goal of preventing data collisions.
In a multidrop connection, data collisions may occur due to data communication between multiple PHYs.
Therefore, as shown in the figure below, a Node ID is set for each PHY, and the Node ID is identified by PLCA to avoid (arbitrate) data collisions.