I'm trying to open a Serial communication between a Raspberry Pi 3 (model B, running on Raspbian) and a device (a traffic counter to be precise).

I've a USB to Serial cable, using the rs232 standard. (so I'm not using the GPIO)

My goal is to be able to open a serial communication between this device and my rpi3 using python and the pyserial library.

(on windows everything works fine, I open a COMx port and I can then communicate with the device)

My problem: When I plug my Serial to USB cable, the rpi3 don't even create a ttyUSB0 device. What is going on ? How could I open a serial communication in python ?

dmesg -w

[ 3482.730866] usb 1-1.4: new full-speed USB device number 9 using dwc_otg
[ 3482.891077] usb 1-1.4: New USB device found, idVendor=0403, idProduct=9bf0
[ 3482.891093] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3482.891102] usb 1-1.4: Product: TrafficCounter USB Adapter
[ 3482.891110] usb 1-1.4: Manufacturer: TrafficCounter
[ 3482.891118] usb 1-1.4: SerialNumber: FTVNFDLZ

If I run a

I obtain:
['/dev/ttyS0', '/dev/ttyAMA0', '/dev/ttyprintk']

And I can see my device with lsusb:


Bus 001 Device 009: ID 0403:9bf0 Future Technology Devices International, Ltd 

/dev/ttyS0 and /dev/ttyAMA0 are inbuilt UARTS /dev/ttyprintk MAY be yours.

NOT all USB devices/drivers are "tty".

Unplug the device, list /dev then plug in and see what has changed.


You need to load the ftdi-sio module manually with modprobe and specifying vendor and product id, or follow the guidelines in their manual at


Afterwards, you'll have a /dev/ttyUSBn.


Thank's for your answers, unfortunately that did not resolve my problem.

I guess that ftdi_sio module do not support anymore the "vendor" and "product" attribute. So

modprobe ftdi_sio vendor=0x0403 product = 0x9bf0

Didn't work for me.

What worked:

I'v added my vendorid and productid in /sys/bus/usb-serial/drivers/ftdi_sio/new_id

sudo nano /sys/bus/usb-serial/drivers/ftdi_sio/new_id

and then i just add:

0403 9bf0

How to automate this process --> here

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