Automotive Ethernet Converter - Practical Application Guide

This article will introduce how to use Automotive Ethernet converters to quickly get started with Automotive Ethernet physical layer.

I. Simplest Automotive Ethernet Environment

Environment Preparation

• Prepare one computer, connected to router via network cable for internet access

Setup Steps

Connect two Automotive Ethernet converters in series between computer and router:

Function of Automotive Ethernet Converter: Converts between standard Ethernet and Automotive Ethernet.

Through two converters, the network path becomes:

• Standard Ethernet → Automotive Ethernet → Standard Ethernet

After the converter link is established, it functions like a special network cable, and the computer can still access the internet normally.

II. Automotive Ethernet 100/1000BASE-T1 Physical Layer Basic Concepts

Master/Slave Mode

Automotive Ethernet devices must follow the "one Master, one Slave" correspondence relationship to establish Link connection.

Speed Matching

The converter supports 100/1000BASE-T1 specifications. Standard Ethernet devices and Automotive Ethernet devices must have matching speeds to communicate normally.

• Both at 100 Mbit/s
• Both at 1000 Mbit/s

III. Testing Impact of Different Cables on Physical Links

SQI (Signal Quality Index)

SQI value is an important basis for judging Automotive Ethernet communication link quality. The converter can directly view SQI changes through the screen.

Example: Replace the Automotive Ethernet cable with 10-meter long standard twisted pair, and both converters display SQI value of 8.

Description: Higher values indicate better quality, with maximum of 15.

Cable Quality Detection

The converter supports detection of the following parameters:

• Insertion Loss (IL)
• Return Loss (RL)

Detection Principle: Use Time Domain Reflectometry (TDR) to determine communication cable quality, capable of diagnosing following issues:

• Short circuits
• Open circuits
• Communication cable impedance mismatch
• Faulty connectors
• Termination mismatch

Description: Higher values indicate better quality, with maximum of 15.

Note: Precise cable quality detection still requires professional equipment. Parameters provided by this device are for reference and comparative use only.

Impact of Distance and Cable Material on Communication

Combining SQI values as well as IL and RL data, qualitative analysis can be performed for:

• Cable quality (good or bad)
• Communication distance
• Impact on Automotive Ethernet communication quality

IV. Speed Testing Considerations

The iperf tool can be used to test maximum network bandwidth.

Test Method

Replace the router in the environment with a second PC:

Server (PC A) Execute:

iperf3.exe -s

Client (PC B) Execute:

iperf3.exe -c 192.168.xx.xx  # Specify server IP

Test Result: Taking 1000BASE-T1 as an example, after passing through Automotive Ethernet converters, test results show that it can maintain 949 Mbits per second, verifying that the converter does not affect communication rate.

Recommendations for Improving Test Accuracy

Test results may be affected by environmental factors, potentially causing rate instability. The following aspects can improve accuracy:

• Use high-performance CPU computer, and do not limit its performance
• Close other software applications
• Set test process to highest priority

V. Automotive Ethernet Troubleshooting

When building networks, communication anomalies are inevitable. Taking this setup environment as an example, troubleshooting can be performed through following points:

Link Status

The LINK status at both ends of the converter can be observed through the screen.

• If displayed as "×", it indicates abnormal connection between converter and adjacent device

Need to Confirm:

1. Whether physical line connection is normal
2. Whether the peer is in connection-waiting state
3. Whether both ends have matching Master/Slave status and speed

Indicator Lights

Through indicator lights, it can be quickly determined whether data is passing through the converter.

Normal Operating State:

• When data passes, T1 and TX indicator lights flash simultaneously (1-2s delay)

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Abnormal Situation:

• Troubleshoot issues on corresponding directional ports through abnormal indicator lights

Packet Counter

Confirm link status through the built-in receive packet counter of the converter device.

• If the receive packet counter increases, it indicates normal physical link with the peer device
• Conversely, need to troubleshoot physical link issues

VI. Standard Ethernet Troubleshooting

As mentioned previously, when the converter successfully converts the network, it's equivalent to a special network cable and does not affect MAC and above-layer protocols, meaning it does not affect frame transmission.

If the converter works normally but communication is abnormal, how should further troubleshooting be performed?

Test Environment Troubleshooting

For this article's test environment, you can remove the 2 converters and troubleshoot network configuration issues after direct cable connection.

Actual Automotive Environment Troubleshooting

If connecting to actual automotive equipment, troubleshooting can be performed from the following two aspects:

IP and Network Configuration

1. DHCP Automatic Acquisition

   • Check whether DHCP related configuration is enabled

2. Static IP

   • Ensure correctness of IP address, subnet mask, and other settings

3. Other Network Configuration

   • Check firewall and other network configurations

Using Wireshark for Packet Analysis

Wireshark can be used to exclude local network card MAC address to check whether frames from other devices are received, thereby confirming physical link status.

Operation Steps:

1. Find Local Network Card MAC Address

1. Filter Out Self-Sent Frames in Wireshark

   !(eth.src == 7c:4d:8f:a4:aa:3a)  # Replace with actual MAC address

Judgment Criteria:

• If unable to receive frames, physical link problem may exist
• If frames can be received, further analysis can be performed based on frame content