No Frames Received!

[liyuan1a]

Required Info
Camera Model	{ L515}
Firmware Version	(Open RealSense Viewer --> 2.50.0)
Operating System & Version	{Win (10)
Kernel Version (Linux Only)	(e.g. 4.14.13)
Platform	PC
SDK Version	{ legacy / 2.<?>.<?> }
Language	{C/C#/labview/nodejs/opencv/pcl/python/unity }
Segment	{Robot/Smartphone/VR/AR/others }

Issue Description

<Describe your issue / question / feature request / etc..>

Why does "No Frames Received!" appear after the software Intel RealSence Viewer runs for a period of time?

[MartyG-RealSense]

Hi @liyuan1a The "No frames received!" warning means that new images (frames) are no longer being received. It looks as though one particular camera in your set of multiple L515s is being affected whilst the others are working normally.

On the affected camera, could you first try unplugging the micro-sized end of the USB cable from the base of the camera, reversing the connector's orientation and plugging it back into the L515 camera, please (USB-C cables are two-way insertion at the micro-sized end). Does doing so make any difference?

[liyuan1a]

We have tried this. After restarting the camera L515, we can receive frames, but after a period of time (about 30s, 1 min or 5 min), some cameras still suddenly appear "No frames received!". It seems that the L515 camera is unstable, which has a great impact on our measurement. How to keep the camera stable during operation？ In addition, when we run, sometimes some cameras are disconnected. We need to restart the computer to connect the camera normally again.

[MartyG-RealSense]

Using several RealSense cameras simultaneously on the same computer can place a high processing burden on the computer's CPU, so a computer with an i7 CPU or higher is recommendable.

I note though that in your lower image you are experiencing time_diff_keeper polling warnings with only one L515 enabled. Would it be possible to download and run the 2.51.1 version of the Intel.RealSense.Viewer.exe program to confirm whether the warnings still occur in that version? Downloading this Viewer will not overwrite your existing 2.50.0 version.

https://github.com/IntelRealSense/librealsense/releases/tag/v2.51.1

The Intel.RealSense.Viewer.exe file should be launched from the folder on your computer that you downloaded it to and not with the Viewer shortcut icon on the Windows desktop.

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Multiple L515s can also experience interference if their fields of view overlap. A solution for this can be to use the L515 multiple camera synchronization system described in the Intel white-paper document at the link below.

https://dev.intelrealsense.com/docs/lidar-camera-l515-multi-camera-setup

The paper states that "[multiple L515 cameras] can be hardware synchronized so that separate cameras project light staggered in time (i.e. to reduce optical interference) and data streams do not occur simultaneously (reducing USB peak bandwidth issues)".

If the cameras are connected directly to USB ports on the computer or to a USB hub that is powered by the computer, using a mains electricity powered USB 3 hub attached to a mains power socket can provide higher stability of power supply to the ports that the cameras are attached to.

[MartyG-RealSense]

Hi @liyuan1a Do you have an update about this case that you can provide, please? Thanks!

[MartyG-RealSense]

Case closed due to no further comments received.