Permission denied opening /dev/bus/usb/003/004

[CesMak]

Hey there,

I want to use a logitech camera c930e with libuvc_ros. I currently have this launch file:

<launch>
  <group ns="camera">
    <node pkg="libuvc_camera" type="camera_node" name="mycam">
      <!-- Parameters used to find the camera -->
      <param name="vendor" value="0x046d"/>
      <param name="product" value="0x0843"/>
      <param name="serial" value=""/>
      <!-- If the above parameters aren't unique, choose the first match: -->
      <param name="index" value="0"/>

      <!-- Image size and type -->
      <param name="width" value="640"/>
      <param name="height" value="480"/>
      <!-- choose whichever uncompressed format the camera supports: -->
      <param name="video_mode" value="mjpeg"/> <!-- or yuyv/nv12/mjpeg -->
      <param name="frame_rate" value="30"/>

      <param name="timestamp_method" value="start"/> <!-- start of frame -->
      <param name="camera_info_url" value="file:///tmp/cam.yaml"/>

      <param name="auto_exposure" value="3"/> <!-- use aperture_priority auto exposure -->
      <param name="auto_white_balance" value="false"/>
    </node>
  </group>
</launch>

This is my device lsusb -v:

Bus 003 Device 004: ID 046d:0843 Logitech, Inc. Webcam C930e
Couldn't open device, some information will be missing
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass          239 Miscellaneous Device
  bDeviceSubClass         2 ?
  bDeviceProtocol         1 Interface Association
  bMaxPacketSize0        64
  idVendor           0x046d Logitech, Inc.
  idProduct          0x0843 Webcam C930e
  bcdDevice            0.13
  iManufacturer           0 
  iProduct                2 
  iSerial                 1 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength         2547
    bNumInterfaces          4
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0x80
      (Bus Powered)
    MaxPower              500mA
    Interface Association:
      bLength                 8
      bDescriptorType        11
      bFirstInterface         0
      bInterfaceCount         2
      bFunctionClass         14 Video
      bFunctionSubClass       3 Video Interface Collection
      bFunctionProtocol       0 
      iFunction               0 
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass        14 Video
      bInterfaceSubClass      1 Video Control
      bInterfaceProtocol      0 
      iInterface              0 
      VideoControl Interface Descriptor:
        bLength                13
        bDescriptorType        36
        bDescriptorSubtype      1 (HEADER)
        bcdUVC               1.00
        wTotalLength          215
        dwClockFrequency       30.000000MHz
        bInCollection           1
        baInterfaceNr( 0)       1
      VideoControl Interface Descriptor:
        bLength                18
        bDescriptorType        36
        bDescriptorSubtype      2 (INPUT_TERMINAL)
        bTerminalID             1
        wTerminalType      0x0201 Camera Sensor
        bAssocTerminal          0
        iTerminal               0 
        wObjectiveFocalLengthMin      0
        wObjectiveFocalLengthMax      0
        wOcularFocalLength            0
        bControlSize                  3
        bmControls           0x00020a2e
          Auto-Exposure Mode

and I also created this file: /etc/udev/rules.d

# UVC cameras
`SUBSYSTEMS=="usb", ENV{DEVTYPE}=="usb_device", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="0843", MODE="0666"`

If I launch the above launch file with camera connected I get this error:

[ERROR] [1551621905.341226531]: Permission denied opening /dev/bus/usb/003/004
[camera/mycam-2] process has died [pid 9685, exit code 255, cmd /opt/ros/kinetic/lib/libuvc_camera/camera_node __name:=mycam __log

any ideas what I did wrong?!

[CesMak]

Close this qustion just found the solution myself:

sudo chmod o+w /dev/bus/usb/001/024 <-- where 024 is port# from the error code

[drjasonharrison-vp-eio]

Since your rules.d isn't giving you write permission, are you sure you are selecting the video device in your udev rule? Does it work if you select the video4linux subsystem? Try this:

SUBSYSTEM=="video4linux", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="0843", MODE="0666"`