Hi Pollen Robotics team and community,
I am having an issue with my Reachy 2023 SDK server.
I have a broken cable on the left arm (I already reported it to be fixed). Previously, despite the broken cable, the SDK server would start and I could still use the other arm, which had a working cable.
I want to clarify that I have not modified anything in the software, I am using SDK 1, and it was working perfectly before.
However, now when I try to launch the SDK server, I get the following error in the dashboard:
reachy systemd[909]: Starting Reachy SDK server service...
reachy systemd[909]: Started Reachy SDK server service.
reachy reachy_sdk_server[3337]: [INFO] [launch]: All log files can be found below /home/reachy/.ros/log/2025-12-17-11-44-19-571608-reachy-3337
reachy reachy_sdk_server[3337]: [INFO] [launch]: Default logging verbosity is set to INFO
reachy reachy_sdk_server[3337]: [ERROR] [launch]: Caught exception in launch (see debug for traceback): Caught multiple exceptions when trying to load file of format [py]:
- DxlCommunicationError: could not parse received data bytearray(b'\x00') after sending DxlPingPacket(id=0)
- InvalidFrontendLaunchFileError: The launch file may have a syntax error, or its format is unknown
I additionally tried launching it directly with the provided script:
./launch.bash
The result is the same error as above and the server hangs. Now I only see one \x00 byte, since the other motors are disconnected or not responding.
I have checked the USB ports:
ls -l /dev/ttyUSB*
crw-rw-rw- 1 root dialout 188, 0 Dec 17 11:58 /dev/ttyUSB0
crw-rw---- 1 root dialout 188, 1 Dec 17 11:59 /dev/ttyUSB1
I tried connecting to each bus individually using Python 3 and pyluos:
from pyluos import Device
device = Device('/dev/ttyUSB0') # or /dev/ttyUSB1
print(device.modules)
However, both buses hang and do not return any modules, indicating that neither bus is responding.
I also tried launching the SDK server using ROS 2:
cd ~/reachy_ws
source install/setup.bash
ros2 launch reachy_sdk_server reachy_sdk_server.launch.py
- The server starts but stays stuck at:
Waiting for /dynamic_joint_states...
Checking ROS 2 topics shows that no joint states are published, only the base topics appear:
ros2 topic list
/back_wheel_rpm
/cmd_vel
/left_wheel_rpm
/odom
/parameter_events
/right_wheel_rpm
/rosout
/scan
/scan_filterd
/tf
This confirms that none of the motors are responding, not even the right arm that was previously working.
I wanted to make sure I could continue working with the arm that had been functional, but now the SDK server cannot start at all, and I cannot access any modules.
Could you please advise how to debug this issue and verify if at least one arm can still work while waiting for the left arm repair?
Thank you in advance!