Can't access turtlebot through ttyUSB0

edit

I had a similar problem, and I'd like to add something to dvbot's extremely helpful response. I couldn't communicate to the my turtlebot netbook, and my Turtlebot Dashboard was all gray. Under Diagnostic, I had the error: TurtleBot Node: Failed to open port /dev/ttyUSB0. Please make sure the Create cable is plugged into the computer.

When trying to implement dvbot's recommendation, I realized my turtlebot netbook didn't have the file /etc/udev/rules.d/52-turtlebot.rules, and I did not have permission to create it. I went here, and found good instructions from tredegar (halfway down the page) in how to overcome the problem. For your convenience, I am recopying some of tredegar's recommendation. To become root issue the command:

sudo -i

Then to create the file you can use the command

gedit /etc/udev/rules.d/52-turtlebot.rules

or use your favorite editor. Once you populate the content with dvbot's code, restart udev:

/etc/init.d/udev  restart

I'm still very new to this, but I do know this worked for me: once I restarted udev, my Turtlebot Dashboard went from gray to greens and reds. Both my workstation and turtlebot netbook are running Ubuntu 11.10 and ros electric. Hope this is useful.

If you are still having this problem, I resolved it by changing adding the turtlebot user to the 'dialout' group. That group owns /dev/ttyUSB0 so by being a member of that group you are added to the ownership. It doesn't affect any other permission at least so that U can detect at this point. I'll keep you posted, unless you already fixed it using another method. Just sharing the info as I find it.

You could check the permissions of ttyUSB0

ls -la /dev/

If the perms are not 666 or a+rw then you need to boot with usb that has permission to access. Basically you need to create a new rule in /etc/udev/rules.d:

Create a new file with your specific permissions (higher numbers override existing rules):

cd /etc/udev/rules.d/
touch 80-turtlebot.rules
sudo pico 80-turtlebot.rules

Add the following lines for every usb device:

#serial usb
SUBSYSTEM=="usb", ATTRS{idProduct}=="6001", ATTRS{idVendor}=="0403", MODE="0666", GROUP="turtlebot"

To find the product id and vendor id, do lsusb -v, I think if you just do regular lsusb its vendor:product. Shift + PgUp to view previous parts of the cli.

finally reboot

sudo reboot