How to use Turtlebot with a serial port other than USBtty0?

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Hi,

I am trying to get Turtlebot to run with a bluetooth serial port on /dev/rfcomm0 instead of USBtty0. I've confirmed that the connection to the Roomba SCI with my Rootooth device via rfcomm0 works correctly outside of Turtlebot and I've replaced the only occurrence of the string USBtty0, I could find in any of the config files, but it still tries to connect to USBtty0 instead of rfcomm0. Can anyone tell me where/how that device name is configured?

Thank you!