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LibUSB/LibFTDI permissions problem


I'm currently developing an application to communicate with some
embedded hardware via an USB<->RS485 / USB<->RS232 converter Tribotix
USB2Dynamixel which is based on the FTDI chip. Here is information
reported by dmesg about this device:

usb 4-2: USB disconnect, address 5
usb 4-2: new full speed USB device using uhci_hcd and address 7
usb 4-2: configuration #1 chosen from 1 choice
ftdi_sio 4-2:1.0: FTDI USB Serial Device converter detected
ftdi_sio: Detected FT232RL
usb 4-2: FTDI USB Serial Device converter now attached to ttyUSB0
usb 4-2: New USB device found, idVendor=0403, idProduct=6001
usb 4-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 4-2: Product: FT232R USB UART
usb 4-2: Manufacturer: FTDI
usb 4-2: SerialNumber: A7003Nzt

The device is registered as /dev/ttyUSB0. 
ls -lah information:

 crw-rw---- 1 root uucp 188, 0 2009-01-08 17:39 /dev/ttyUSB0

To have access to the device, I added my user to the uucp group.

My application uses LibFTDI to communicate with attached devices and
works properly under a Zenwalk (Slackware) configuration out of the box.
Under Fedora 10 there is a failure while opening the device. LibUSB's
usb_strerror() reports "could not set config 1: Operation not
permitted", LibFTDI's ftdi_get_error_string() reports "inappropriate
permissions on device!". Executing with root rights works. The failure
occurs on ftdi_usb_open

Neither chmodding nor chowning /dev/ttyUSB0 fixes the problem.
setenforce 0 has also no impact on problem resolution, there are no
SELinux reports.

Additionally: after closing the device on execution as root, it gets
removed and the converter has to be replugged.

Is there anything I'm missing?

Thank you in advance!
 -- Dmitri Bachtin

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