Error: there is no device at the given index or name

[yechun1]

build code based on ros-crystal-desktop

$ ros2 run composition api_composition

[INFO] [api_composition]: Load library /data/proj/oa/ros2_ws/install/movidius_ncs_stream/lib/libmovidius_ncs_stream.so
[INFO] [api_composition]: Instantiate class movidius_ncs_stream::NCSComposition
[DEBUG] [movidius_ncs_lib]: NCSImpl get parameters
[INFO] [movidius_ncs_lib]: use device_index = 0
[INFO] [movidius_ncs_lib]: use log_level = 0
[INFO] [movidius_ncs_lib]: use graph_file_path = /opt/movidius/ncappzoo/caffe/SSD_MobileNet/graph
[INFO] [movidius_ncs_lib]: use category_file_path = /opt/movidius/ncappzoo/data/ilsvrc12/voc21.txt
[INFO] [movidius_ncs_lib]: use cnn_type_ = mobilenetssd
[INFO] [movidius_ncs_lib]: use network_dimension = 300
[INFO] [movidius_ncs_lib]: use channel1_mean = 127.5
[INFO] [movidius_ncs_lib]: use channel2_mean = 127.5
[INFO] [movidius_ncs_lib]: use channel3_mean = 127.5
[INFO] [movidius_ncs_lib]: use top_n = 1
[INFO] [movidius_ncs_lib]: use scale = 0.007843
[ERROR] [movidius_ncs_stream]: Error: there is no device at the given index or name

launch ros2 pkg prefix movidius_ncs_launch/share/movidius_ncs_launch/launch/ncs_stream_launch.py

(movidius_ncs_stream) pid 7002: ['/opt/ros/crystal/lib/composition/api_composition_cli', 'movidius_ncs_stream', 'movidius_ncs_stream::NCSComposition'] (stderr > stdout, all > console)
[movidius_ncs_stream] [INFO] [api_composition_cli]: Sending request...
[movidius_ncs_stream] [INFO] [api_composition_cli]: Waiting for response...
[movidius_ncs_stream] [INFO] [api_composition_cli]: Result of load_node: success = true
(movidius_ncs_stream) rc 0
() tear down

[EwingKang]

I've found that the ROS2 RealSense + Movidius package is quite unstable.

First, if we don't consider the OA, running in the sequence of Realsense -> composition -> ncs_stream_launch will lead to the same issue, the NCS node driver could not found the NCS stick.
However, if the order is composition -> ncs_stream_launch -> RealSense, it will almost certainly work.
Notice that after each failed attempt, you'll have to unplug both RealSense and Movidius and plug them back in again.

I think the stability of ROS2 NCS and RealSensee is something that needs to be vastly improve...