Network & DDS Configuration

The RBQ ROS 2 driver uses CycloneDDS as its middleware. This page explains how to configure the network so that your developer PC can discover and exchange topics with the robot.

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Network topology

Host	Role	Default IP
Wi-Fi Access Point	L2 bridge between robot and user PC	192.168.0.1
Robot PC (Motion)	Runs rbq_driver, publishes all topics	192.168.0.10
Developer PC	Runs your ROS 2 nodes	192.168.0.12 (DHCP)

Both machines must be on the same subnet (192.168.0.0/24) and reachable via ping before DDS discovery will work.

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Required setup

1. Set the RMW implementation

Both the robot driver and your terminal must use CycloneDDS:

export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp

Add to ~/.bashrc to persist across terminals:

echo 'export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp' >> ~/.bashrc
source ~/.bashrc

2. Domain ID

ROS_DOMAIN_ID is not set by the robot or any RBQ script — both sides use the default domain 0. No extra configuration is needed.

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Verify connectivity

# 1. Ping the robot
ping 192.168.0.10

# 2. Check topics appear
ros2 topic list

# 3. Echo a live topic
ros2 topic echo /rbq/imu/IMU_state --once

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Firewall

If ros2 topic list returns nothing but ping succeeds, UFW may be blocking multicast:

# Allow DDS traffic on the Wi-Fi interface (replace wlp4s0)
sudo ufw allow in on wlp4s0
sudo ufw allow out on wlp4s0

# Or disable UFW entirely for testing
sudo ufw disable

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Troubleshooting

No topics appear

1. Confirm both machines are on the same subnet: ping 192.168.0.10
2. Confirm RMW_IMPLEMENTATION=rmw_cyclonedds_cpp is set in every terminal you use
3. If you have multiple network interfaces (Wi-Fi + Ethernet), specify the correct one explicitly:

export CYCLONEDDS_URI='<CycloneDDS><Domain><General><Interfaces>
  <NetworkInterface name="wlp4s0"/>
</Interfaces></General></Domain></CycloneDDS>'

Replace wlp4s0 with your Wi-Fi interface name (ip link show to check).

Topics appear but lag or drop

Multicast may be unreliable over some Wi-Fi routers. Add a unicast peer hint:

export CYCLONEDDS_URI='<CycloneDDS><Domain><General>
  <Interfaces><NetworkInterface name="wlp4s0"/></Interfaces>
</General><Discovery><Peers><Peer address="192.168.0.10"/></Peers></Discovery>
</Domain></CycloneDDS>'

rbq_msgs types show as unknown

The custom message package must be built and sourced on your PC:

cd ros2
colcon build --packages-select rbq_msgs
source install/setup.bash