Once stopped, cannot find the camera again.

[JNiss3]

Camera ModelSR300HardwareJetson TX2 with Orbitty CarrierOperating System & VersionUbuntu 16.04Kernel Version (Linux Only)4.4.15-tegra on Jetson TX2

Problematic Szenario

The camera is connected to the Jetson over a USB 3.0 Hub and a USB 3.0 extension cable with booster. Once the camera is started with "roslaunch realsense_camera sr300_nodelet_rgbd.launch" everything works fine. Then I stop the camera with ctrl + C. When I then start the camera again with the launch file, it does not find the camera and lsusb does not show the camera.

The error is:

[ERROR] [1497343628.338504027]: /camera/driver - No cameras detected!

Working Szenario

1. The camera is connected to the Jetson only over the USB 3.0 Hub. I can launch the camera with the launch file, stop it with ctrl + C and restart the camera. Everything works fine.

2. The camera is connected to the Jetson (but with developer kit not orbitty carrier) over the same USB 3.0 Hub and USB 3.0 extension cable with booster. Everything works fine.

Does someone has an idea what to test or a solution? Thanks for your support!

[MartyG]

How long is your USB extension cable, please? RealSense cameras do not do well with extension cables due to the large amount of data that they transmit. The maximum length that others have had most success with is 1 m. It was found that with 2 m cables, the camera would not function except in cases where a premium high-grade 2 m extension cable was used.

[JNiss3]

Thanks for your fast answer! I am not sure how long the cable is exactly. I think it is 3m, but as decribed in the working szenario, when I connect the camera with this USB extension cable and the Jetson with the developer kit, it works. Only with the Orbitty Carrier Board it does not work.

[MartyG]

Ok, so you are using Ctrl-C to shut down the nodelet manager of ROS. There is nothing wrong with shutting ROS processes down this way as far as I know, and as you said, it works fine for you except when using the Orbitty Carrier Board. I'm not a ROS expert, but I wonder if Ctrl-C also shuts down the Orbitty board.

There was a case where someone could not relaunch an Arduino board with ROS after doing Ctrl-C.

https://github.com/hbrobotics/ros_arduino_bridge/issues/31 Using Ctrl+C on an Embedded Board can cause re-connection problem · Issue # 31 · hbrobotics/ros_arduino_bridge · GitHub

In that case, the connection problems were fixed by using the master branch.