No ttyUSB when connecting USB-RS485 to Beaglebone Black

I'm trying to connect a externally powered board to control the motors of a robot to my BeagleBone Black. I'm using ssh over USB(the mini-usb) to control the Beaglebone from my laptop. The BBB is running ubuntu arm:

Linux arm 3.14.22-ti-r31 #1 SMP PREEMPT Sat Oct 25 01:30:27 UTC 2014 armv7l armv7l armv7l GNU/Linux

The external board(a threemxl) I plug in is supposed to use the BBB as host and communicate over the standard USB port of the BBB. For this it uses a USB-RS485 connector. Now when I plug the external board into my laptop running elementary it automatically shows up on /dev/ttyUSB0, but it does not do this on the Beaglebone. This is what dmesg tells me :

[ 5695.486503] usb 2-1: new full-speed USB device number 5 using musb-hdrc
[ 5695.634339] usb 2-1: device v0403 p6001 is not supported
[ 5695.641400] usb 2-1: New USB device found, idVendor=0403, idProduct=6001
[ 5695.641457] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 5695.641498] usb 2-1: Product: USB-RS485 Cable
[ 5695.641536] usb 2-1: Manufacturer: FTDI
[ 5695.641573] usb 2-1: SerialNumber: FTX12FXD

and lsusb with the board connected.

Bus 002 Device 006: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

I'm guessing it is some sort of driver issue. I have tried adding the following udev rule:

SYSFS{idProduct}=="6001", SYSFS{idVendor}=="0403", RUN+="/sbin/modprobe -q ftdi-sio product=0x6001 vendor=0x0403"

But honestly I'm not sure what effect this is supposed to have or how to enforce this rule. Any help would be appreciated.