nros communicates with standard ROS 2 nodes via rmw_zenoh_cpp. Both sides connect to the same zenohd router (or peer directly).
Quick Start (3 Terminals)
# 1. Start zenoh router
ZENOH_CONFIG_OVERRIDE='listen/endpoints=["tcp/127.0.0.1:7447"];scouting/multicast/enabled=false' ros2 run rmw_zenoh_cpp rmw_zenohd
# 2. Run the nros C talker (see Getting Started for build steps)
./my_c_talker
# 3. Run a ROS 2 listener
source /opt/ros/humble/setup.bash
export RMW_IMPLEMENTATION=rmw_zenoh_cpp
ros2 topic echo /chatter std_msgs/msg/Int32 --qos-reliability best_effort
Requirements
- RMW implementation: set
RMW_IMPLEMENTATION=rmw_zenoh_cpp on the ROS 2 side.
- QoS: nros defaults to BEST_EFFORT reliability. Pass
--qos-reliability best_effort on the ROS 2 subscriber, or configure both sides to use RELIABLE.
- zenohd version: both zenoh-pico (used by nros) and zenohd must be the same version. Version mismatches cause transport failures.
Common Issues
- Topic not visible in
ros2 topic list — nros must declare liveliness tokens (handled automatically by the transport layer). Verify zenohd is reachable from both sides.
- No messages received — check that the data key expression uses
TypeHashNotSupported (Humble) not RIHS01_… in the data topic. This is handled automatically when using the ros-humble feature.
- QoS mismatch — nros defaults to BEST_EFFORT; pass
--qos-reliability best_effort on the ROS 2 subscriber.
- rmw_zenoh not connecting — force client mode on the ROS 2 side:
export ZENOH_CONFIG_OVERRIDE='mode="client";connect/endpoints=["tcp/127.0.0.1:7447"]'
- Humble vs Iron — Humble uses
TypeHashNotSupported; Iron+ uses RIHS01_<sha256> (requires building with the ros-iron feature).
