Trouble connecting multiple cameras

• MartyG

  • July 13, 2022 11:07
  • Edited

  Hi P Woronow  As the problem is occurring a while after the session has started, if the camera's operating temperatures are within recommended maximum limits then it is likely that the problem is occurring due to something other than the camera hardware.  This could include a glitch on the USB port or cable, the computer hardware or the computer's operating system.

   

  The chance of unforeseeable consequences in regards to stability could also increase if you are using Ubuntu as your operating system and are using a kernel that is not currently supported by default in the RealSense SDK.  For example, version 2.50.0 of the RealSense SDK (librealsense) supports kernel 5.4 when installed from packages and up to kernel 5.8 and 5.11 when built from source code. 

   

  Whilst newer non-supported kernels can be used with the SDK, the aforementioned possibility of instability could occur.

   

  A draft kernel patch has recently been released at the link below to add support to the SDK for kernel 5.13 and 5.15.

  https://github.com/IntelRealSense/librealsense/pull/10625

   

  A pre-built package for testing the patch is here:

  https://github.com/mengyui/librealsense2-dkms/releases

   

  May I also ask which method you used to install the SDK?  A build based on kernel patching will be more suited to multiple cameras than one built from source code with the RSUSB backend installation method.

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• P Woronow

  • July 13, 2022 11:20

  As for the operating system, I use Windows. As for the time of turning off the cameras, it is not fixed, sometimes they turn off after 10 seconds and sometimes after 20 minutes. As for the usb cable, I use the manufacturer's cables. I built an SDK based on the github code

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• MartyG

  • July 13, 2022 11:30

  Thanks very much for the information.  A short and unpredictable time period of between 10 seconds and 20 minutes increases the likelihood that there is an issue in the program rather than the hardware.  Are you using the RealSense SDK's RealSense Viewer tool or a program that you have created yourself, please?

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• P Woronow

  • July 13, 2022 11:41

  I made the program in c ++. I am using library Librealsense2 / rs read-only frames in a separate thread. Can I hang the camera while reading the frame?

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• MartyG

  • July 13, 2022 11:54

  A camera connection may 'time out' if new frames are not received for 5 seconds.  If only some of the cameras are stopping then it would seem to be an issue related to individual camera connections and not a freezing / exit of the entire program.

   

  Does your program code use the instruction wait_for_frames() ?  If it does then poll_for_frames() is recommended for a program that is accessing multiple cameras.

  If poll_for_frames() is already used in your program then it is advisable to control when the CPU sleeps and for how long, as described at the link below.

  https://github.com/IntelRealSense/librealsense/issues/2422#issuecomment-423254709

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• P Woronow

  • July 13, 2022 14:27

  I didn't know about it. I'm using "wait_for_frames ()", I'll check your theory and let you know if it helped thanks a lot :)

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