Serial download from a digital tachograph in python

Digital tachographs are a compulsory equipment for heavy trucks in the european union. The companies owning these trucks have to download the data at least once every 3 months.

Without dedicated hardware, this was so far not easily possible in linux, but my python script should make it possible to download the data with a serial cable with the right connector.

Ubuntu package

Ubuntu packages are available in my ppa. You can add my ppa with

sudo apt-add-repository ppa:k-2005

and then install loadVu with

sudo apt-get install loadvu


Start the program with


The data will be saved to a file named after the vehicle and date.
If your serial connection is not /dev/ttyUSB0, you should specify it with the –serial parameter. A possible call would be

./loadvu --serial /dev/ttyUSB1

Extra transfer response parameters

While the commision regulation 1360/2002 defines TREPs 1 to 6

TRTP/TREP Description
1 Overview
2 Daily Activity on a specified date
3 Events and faults
4 Detailed speed
5 Technical data
6 Card download

At least the digital tachographs from Siemens VDO return data on other requests, too. For example Daimler’s TCO-DKG program requests 17,19 and 20 and saves those to an .add file. The vu also returns data requesting trtp 18. To mimic the behaviour of tco-dkg, type

./loadvu --treps 2,3,4,5 -o mycar.esm
./loadvu --treps 17,19,20 -o mycar.add

Download of card data

It is possible to download the data stored in a driver card inserted into the vehicle unit. However, in the current version the script will add vehicle data to the file, so few programs will be able to read it. The current svn of readesm can, but the last release cannot.

./loadvu --treps 6 -o card.esm

Future versions might handle this with more elegance.

Download Speed

With a digital tachograph from 2007, loadvu tells:

$ ./loadvu
Sending 'Request Start Communication Request'
Got the expected response
Sending 'Request Diagnostic Session'
Got the expected response
Sending 'Request Request Byte rate 115200'
Got the expected response
Sending 'Request Stop Communication'
Got the expected response
data saved to UL-XX YYY 2010-11-09 to 2011-11-18 21.54 (CET).esm
Got 222772 Byte in 1789.75275612 seconds. (124.470823827 Byte/s)

It’s slow. Really slow. Considering how many trucks there are, also expensively slow. And it’s not just this script, it’s that slow with any program. Why? Hard to tell. The transfer is slowest when transferring daily activities, where many cryptographic signatures are transferred. However, there is no technical reason why these would have to be generated at every download, as the data really should not change once written.

Enjoy the script.

filetype loadvu-2011.11.tar.gz (4.96 kiB, 2011-11-18)

This entry was posted in Computers, Vehicles and tagged , , , . Bookmark the permalink.

17 Responses to Serial download from a digital tachograph in python

  1. asker says:

    Do you no any freeware/opensource windows/unix cmdline/gui program for downloading driver card data using the chipcard reader (SCR3311)?

  2. Andreas Goelzer says:

    asker: try fahrlinx. Has some bugs, hasn’t had a release in a while, but works with a similar card reader here.

  3. andi says:

    Do you know where can I get that 6-pin connector? Is there any other way than buying an out of the box solution which includes a cable?

  4. Matija says:

    asker, you can check IB.TCR for windows – or direct donwload link

    downloads with any smartcard reader visible by your windows…

    currently, new release with digital signing and server upload is being prepared. it will be most probably shareware or commercial. (version given in upper links is free)

  5. John says:

    Did you try this only on VDO/Siemens equipment? I’ve heard that the VDO tachographs are painfully slow (up to 30 mins), whereas Stoneridge tachos are just slow (about 5 mins). I can’t think of any technical explanation for this, but having seen VDOs PC software “TIS Office”, I strongly suspect incompetence to be the reason.

  6. Tomas says:

    Hi Matija,
    Do you have software for downloading data from VU?

    Thank you in advance!

  7. Matija says:

    Tomas, unfortunately I don’t have VU download solution.
    Had some plans to implement it, but couldn’t get appropriate cable (e.g. usb-to-VU 6pin).

  8. Andreas Goelzer says:

    John: Yes, Siemens equipment, > 30 minutes for a full year download, more or less independent of the baud rate. I suspect incompetence is the reason for this as well.

    andi, matija: From what i understand from skimming the european regulation, the connector should just be a 5 V-uart interface, so I guess a ft232rl and a couple of connectors would be enough. Unfortunately most off-the-shelf usb converters pair the usb-serial-converter with a rs-232 interface with +-15 V, which won’t help much.

    As in my new job I do not have access to trucks or anything else containing a tachograph, I can’t test if it’s really a 5v-serial-interface.

  9. Michal says:

    Here they say that tachograph download cable uses “FT232R chip”:

    Here they have USB-to-tachograph cable for 70eur here

    There must be other way….FT232RL USB to Serial Download Module costs about 7 eur (dealextreme), don’t know if that works. Anyway, prices for tachograph related devices and software are over the roof because of all this obscurity and non-standard techniques. It would be great to have a cheaper alternative, mainly for small businesses.

  10. Andreas Goelzer says:

    Michael: I have several ft232rl lying around, used one in my servo controller ( ). At electronics shops like csd electronics they are around 3.50 € plus shipping in small quantities. And you wouldn’t need much more, the chip, a pcb, connectors and a couple of capacitors.

    The electrical interface is documented quite well in the regulation, so it would be possible to build one.

    However, actually selling electronics is quite difficult, apart from your work and time some expensive lab measurements are needed to be sure you fulfill the EMC requirements, so development costs go up by around 1500 €, so starting by selling some handmade boards is uneconomic.

    I’m really wondering why the price for truck-connectors is still this high. The market isn’t that small, the hardware simple, I guess the people considering it are just so frustrated by the abysmal download speeds.

  11. JANDER says:

    Hello Andreas, first of all I want to thank you for this great project!

  12. ALBERT says:

    Hello Andreas, i download the script , but don’t run in ubuntu 14.04.
    You know why?

  13. Driver says:

    Hi Andreas,

    is there a chance that readsm is also usable with Ubuntu 14.04 (64-bit)? After compiling i have no chance to do the make install command. Do you support that software anymore?

  14. Wendlinger Robert says:

    Hallo Herr Gölzer,

    Ihr loadvu hat mir geholfen, den Download zu verstehen.
    Zu den Send/receive Strukturen habe ich doku gefunden.
    Ich möchte den Download Ohne im Tacho gesteckte Unternehmenskarte ausführen, finde dazu für die Frontschnittstelle keine Doku. Mit CAN kann ich das schon
    mit zugriff per TCP/IP auf einen entfernen Kartenleser.
    Haben Sie info darüber oder bessere Idee, danach zu suchen.
    Gerne können wir auch telefonieren. 0175/4378904
    Wendlinger Robert

  15. Jander says:

    Hello guys !

    Andreas, I’ve been working with your program for years and I’m really grateful to you.

    I wish you a good new year party 31/12/2017

  16. drapolas says:

    you can use mobilena or tachostore of SOLID softwares to download VU.
    there’s softwares can use a serial cable to download data.
    you can check in french topic:

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