Capturing DLT Logs#

This guide configures a minimal setup for capturing DLT logs on a loopback interface. The demo_app application uses mw::log to generate log messages, while the datarouter daemon transmits these messages as UDP packets over the network for capture on the loopback interface.

Prerequisites#

Software Requirements#

  • DLT capture tool (choose one):

System Requirements#

  • x86 target platform

  • Network loopback interface (127.0.0.1) and Docker interface (172.17.0.1) configured and operational as multicast interfaces.

  • UDP port 3490 available for DLT traffic

Datarouter Setup#

Installation Structure#

Deploy the datarouter daemon with the following directory structure:

/opt/datarouter/
├── bin/
│   └── datarouter
└── etc/
    ├── logging.json
    └── log-channels.json

Note: Reference configuration files are available in the ./etc directory.

Starting the Datarouter#

Execute the datarouter daemon on x86 targets:

./datarouter --no_adaptive_runtime &

The --no_adaptive_runtime flag bypasses Adaptive runtime requirements for standalone operation.

Demo Application Setup#

Installation Structure#

Deploy the demo application with the following structure:

/opt/demo_app/
├── bin/
│   └── demo_app
└── etc/
    └── logging.json

Running the Application#

Execute the demo application to generate log messages:

./demo_app

Assunption is that the application uses mw::log to log structured debug log messages.

Capturing DLT Logs#

Option 1: Using dlt-receive (Command-Line)#

Capture DLT messages on the loopback interface using the command-line tool:

./dlt-receive --udp --net-if 127.0.0.1 --port 3490 -a

Parameters:

  • --udp: Enable UDP reception mode

  • --net-if 127.0.0.1: Bind to loopback interface

  • --port 3490: Listen on default DLT UDP port

  • -a: Display all messages in ASCII format

Option 2: Using DLT Viewer (GUI)#

  1. Launch dlt-viewer.

  2. Open ECU Configuration and select the UDP tab.

  3. Configure the connection:

    • Receiving interface: Select the network interface on which the datarouter is transmitting (for example, eth0, enp0s3, wlan0, or another interface available on your platform).

    • IP Port: 3490

  4. If multicast is enabled in the datarouter configuration:

    • Enable Multicast on network interface.

    • Set the Multicast address to the address configured in log-channels.json (for example, 239.255.42.99).

  5. Apply the configuration and start capturing to view real-time DLT log messages.

Option 3: Using Wireshark#

  1. Launch Wireshark

  2. Navigate to Capture menu

  3. Select Adapter for loopback traffic capture

  4. Apply display filter: udp.port == 3490

  5. Start capture to monitor raw DLT UDP packets

Option 4: Using Chipmunk (GUI)#

  1. Download and install Chipmunk.

  2. Launch Chipmunk and create or open a UDP stream.

  3. Configure the connection:

    • Socket Address: <ip>:3490 (replace <ip> with the IP address of the network endpoint on which the datarouter is transmitting. For example, if the datarouter application and client are running on the same machine, use 0.0.0.0:3490,)

  4. If multicast is enabled in the datarouter configuration:

    • Address: Set the multicast address configured in log-channels.json (for example, 239.255.42.99).

  5. Interface Address : Enter the IP address of the network Interface.

  6. Start the stream to view incoming DLT log messages.

Verification#

Verify the setup operates correctly by checking:

  1. Datarouter process: Confirm the daemon runs without errors

    ps aux | grep datarouter

  2. Network binding: Verify UDP port 3490 listens on loopback

    netstat -uln | grep 3490

  3. Log output: Observe DLT messages appear in the capture tool when executing demo_app

Troubleshooting#

No DLT messages received#

  • Verify datarouter daemon runs with --no_adaptive_runtime flag

  • Check UDP port 3490 availability: netstat -uln | grep 3490

  • Confirm loopback interface configuration: ip addr show lo

  • Validate configuration files in /opt/datarouter/etc/

  • Ensure the datarouter daemon and the DLT client are running before starting the application.

Configuration file errors#

  • Verify JSON syntax in logging.json and log-channels.json

  • Check file permissions allow read access for datarouter process

  • Review datarouter logs for configuration parsing errors