Startup failure

[CaptD]

Hey,

I used a urg-04lx-ug01 on a mobile robot. I added urg_node in startup application in ubuntu 16.04, and added chmod 666 /dev/ttyACM0 in the script and sleep for 2 seconds before launching the node. However, the urg lidar cannot be opened sometimes, one failure out of ten boots. When it failed, I could see /dev/ttyACM0, but was not able to launch the node manually. All I need to do is unplug the usb cable and replug it, and then the lidar resume working.

Is this a driver issue or a hardware issue? How can I avoid this issue?

Thanks in advance!

[dietriro]

Hi you can maybe try adding the user that you are starting the node with to the dialout group:

usermod -aG user dialout

This allows the user to always read from /dev/ttyACM0 without having to modify any access rights. Maybe it is just a race condition, that would be my idea. If it is an implementation bug I have no clue what it can be.