I am not able to start owserver without sudo on a LinkUSB with ftdi addressing.

I have an udev rule that works for owserver and the LinkUSB, creating a symbolic link to /dev/ttyUSB<n> and setting the group to 'owsrv' and the mode to group can read/write /dev/ttyUSB<n> looking like:


SUBSYSTEMS=="usb", ATTRS{manufacturer}=="FTDI", ATTRS{product}=="FT232R USB UART", ATTRS{serial}=="A800bXHr", GROUP="owsrv", MODE="0664", SYMLINK+="LinkUSB"

BUT since the owserver with ftdi addressing takes down ttyUSB<n>, like syslog says:

/ftdi_sio ttyUSB0: FTDI USB Serial Device converter now disconnected from ttyUSB0
    ftdi_sio 3-1.1:1.0: device disconnected/

(btw: it does not have the courtesy to put it back afterwards either ;) )

So, a different interface has to be used by owserver with ftdi direct communication and like Johan mentioned

    "chown/chgrp some node in /dev/usb/something"

I check there first, but my /dev has no /usb directory, but it has a bunch of 'usbdevX' which lsusb tells me that usbdev3.17 is my LinkUSB:

/lsusb
    ...
Bus 003 Device 017: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
    ...
/
so, for test-purposes I changed the manually the group of usbdev3.17 to 'owsrv' and added 'rw' for the group

/ls -al /dev/usbdev3.17
    crw-rw---- 1 root owsrv 189, 272 Aug  8 19:48 /dev/usbdev3.17
/
but still owserver gives me 'permission denied' in the debug

/DEBUG MODE
    libow version:
        3.2p1
  DEBUG: ow_daemon.c:(170) main thread id = 3069509632
  DEBUG: ow_inotify.c:(80) No configuration files to monitor
CONNECT: ow_dnssd.c:(81) Zeroconf/Bonjour is disabled since dnssd library isn't found
   CALL: ow_parsename.c:(104) path=[]
DEBUG: owlib.c:(77) Global temp limit 0C to 100C (for fake and mock adapters)
  DEBUG: ow_com.c:(47) Auto initialization of ftdi:s:0x0403:0x6001:A800bXHr
CONNECT: ow_ftdi.c:(213) [Permission denied] Failed to open FTDI device with description 's:0x0403:0x6001:A800bXHr': -4 = usb_open() failed
  DEBUG: ow_link.c:(328) Detecting ftdi LINK using 9600 bps
CONNECT: ow_ftdi.c:(213) [Permission denied] Failed to open FTDI device with description 's:0x0403:0x6001:A800bXHr': -4 = usb_open() failed
/...
CONNECT: owlib.c:(216) Cannot open LINK bus master at ftdi:s:0x0403:0x6001:A800bXHr
  DEBUG: ow_link.c:(857) LINK_close called on already closed connection
DEFAULT: owlib.c:(52) No valid 1-wire buses found

Question is: *which device is to change permissions and group, so owserver with a LinkUSB with ftdi addressing can be started without sudo?*
Next question ;)  what would the udev rule look like?



Sidenote: the keys of udev seem to change rather often. What was SYSFS years ago, seems now to be ATTRS.
I found, that a good way to check what udev knows about your device is:

/udevadm info -a -p $(udevadm info -q path -n ttyUSB0)/

the option -p expects a systempath, which I found rather hard to figure out, until I found the above solution, where the path /$(udevadm info -q path -n ttyUSB0) /rather cleverly is given by udevadm itself, which in my case results in:

//devices/platform/sw-ehci.2/usb3/3-1/3-1.1/3-1.1:1.0/ttyUSB0/tty/ttyUSB0/

but I have no idea where in the system this path exists. Is that only in udev-land or what?
I found the same info in

    ls -al /sys/bus/usb-serial/devices/
...
lrwxrwxrwx 1 root root 0 Aug 9 19:36 ttyUSB0 -> ../../../devices/platform/sw-ehci.2/usb3/3-1/3-1.1/3-1.1:1.0/ttyUSB0

and again where does this symlink point to? I don't know where it resides...

Sidenote 2: to get the ttyUSB<n> back, once owserver took it down, instead of getting up, walking over to the actual device un- and re-plugging it, it is more efficient :) to unload and reload the ftdi_sio module:

    sudo /rmmod ftdi_sio
    sudo modprobe ftdi_sio


/Martin/
/
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