Help: Establishing Communication via Serial

[PedroAcero]

Hello,
I am an undergraduate student testing the Zenoh bridge for my ROS2 project. I'm trying to communicate between two different computers using Zenoh. On the laptop1, I have installed the Zenoh bridge, and I have built it as a ROS2 package, following the repository instructions.

On the laptop2, I don't have ROS2 or Zenoh installed, so I created a Docker container using this Dockerfile. I built the container with the following command:

docker run -v /var/run/dbus/:/var/run/dbus/:z -it --name zenoh_container --cap-add=SYS_ADMIN --cap-add=NET_ADMIN --net=host --privileged ros_prueba:latest /bin/bash  

With the setup ready, I tested the bridge with the following commands:

Laptop2

• terminal1:

    ros2 topic pub -r 1 topic_test std_msgs/msg/String "data: 'Hello World'"  
  

• terminal2:

    zeno-bridge-ros2dds -e tcp/192.168.0.25:7447    
  

[!NOTE]: 192.168.0.25 it's my IP address in this specific case, but it needs to be changed for each instance. Both laptops must be in the same local network.

Laptop1

• terminal1:

    zeno_bridge_ros2dds  
  

• terminal2:

    ros2 topic echo /topic_test  
  

With this basic test, it can be verified that the Zenoh bridge performs the discovery process, and both laptops see and connect to each other. So far, there are no problems.

The next step is that I would like to test other methods of communication, besides the computer's Wifi interface. For this purpose, I have two 433 MHz Wi-Fi antennas (Sik Radio). I connected both antennas via usb Serial to the laptop1, testing the communication between both devices with this two pyserial programs.

I now intend to connect the two laptops through the antennas, connected to the USB0 port of each laptop respectively. Following the Zenoh instructions to connect two devices via the serial port, I entered the following command:

zenoh_bridge_ros2dds -l "serial//dev/ttyUSB0#baudrate=57600" -l "tcp/127.0.0.1:7447"  

However, I get the following error:
[2024-05-22T14:31:57Z INFO zenoh_bridge_ros2dds] zenoh-bridge-ros2dds v0.11.0-dev-24-gd5d6a95 built with rustc 1.72.0 (5680fa18f 2023-08-23) [2024-05-22T14:31:57Z INFO zenoh::net::runtime] Using PID: c57be5548da4c3c170891f3f32545ca5 [2024-05-22T14:31:57Z ERROR zenoh::net::runtime::orchestrator] Unable to open listener serial//dev/ttyUSB0#baudrate=57600: Unsupported protocol: serial. at /home/pedro/.cargo/git/checkouts/zenoh-cc237f2570fab813/b669489/io/zenoh-link/src/lib.rs:140. thread 'main' panicked at 'calledResult::unwrap()on anErrvalue: Unsupported protocol: serial. at /home/pedro/.cargo/git/checkouts/zenoh-cc237f2570fab813/b669489/io/zenoh-link/src/lib.rs:140.', zenoh-bridge-ros2dds/src/main.rs:77:62 note: run withRUST_BACKTRACE=1environment variable to display a backtrace Aborted (core dumped)

Am I doing something wrong? Am I missing any additional configuration in my setup? Any help and recommendations for the project would be appreciated.

[PedroAcero]

Problem solved!!

I had to add the serial features to the Dockerfile:

RUN cargo build --release --features zenoh/transport_serial  

In addition to this, I had to set one side as connecting, and the other as listening:

zenoh-bridge-ros2dds -e "serial//dev/ttyUSB0#baudrate=57600"
zenoh-bridge-ros2dds -l "serial//dev/ttyUSB0#baudrate=57600"  

This question was solved in the Discord community. In their channel they are very active, and they solved my issues with great speed and clarity. I would recommend joining this channel because they are very nice and they keep informed of the updates of this project.