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The two tachograph versions look almost identical in terms of design. However, the new DTCO 4.1 has a direct identifying feature. A small Bluetooth icon on the top right of the display identifies the new device.

Direct access to the DTCO 4.1 via the VDO Fleet App is possible via this Bluetooth interface. The VDO Fleet App can be downloaded for Android or iOS devices via the following links (paste the links here). With the DTCO 4.1, no additional hardware such as the DTCO SmartLink Pro is required for access. Bluetooth connectivity brings improvements for both drivers and companies.

Even if the DTCO 4.1 is almost unchanged in terms of design and adopts all the improvements that were introduced with the DTCO 4.0(e), almost all hardware and software components have been redesigned or changed compared to the DTCO 4.0(e). The DTCO 4.1 has stored a digital map and automatically records border crossings. The regulations newly introduced with the EU mobility package I have been taken into account, for example the special rule in cross-border freight transport, which makes it possible to take two reduced weekly rest periods in a row.

There is also a so-called "Ex variant" of the DTCO 4.1, which is intended for vehicles that transport dangerous goods in accordance with the ADR agreement. Tachographs that meet the special requirements for the transport of potentially explosive goods or in potentially explosive environments can be identified by the "Ex symbol" above the tachograph display.

Analog tachographs

In vehicles that were registered for the first time on the road before 30.4.2006, analogue tachographs are installed, which record on record sheets (also called speedometer discs).

Digital tachographs – Generation 1

From 1.5.2006, for the first time, registered vehicles used for journeys subject to recording had to be equipped with a digital tachograph. These are referred to as the first generation (G1) of digital tachographs. Since some technical adjustments have had to be made over the years, for example to improve the tamper-proofing of the devices, to record a second motion signal or to integrate the so-called one-minute rule, there are a total of three versions of the first-generation digital tachographs. The first version (G1V1) was installed until 30.9.2011, the second version (G1V2) between 1.10.2011 and 30.9.2012 and the third version (G1V3) between 1.10.2012 and 14.6.2019.

In the case of VDO's DTCOs, release versions 1.0 to 3.0a belong to the first generation.

Digital tachographs – Generation 2

Vehicles registered for the first time on or after 15.6.2019 must have the so-called "intelligent" digital tachograph, which, for example, can transfer fleet management data to the company via the so-called ITS interface (Intelligent Transportation System), is connected to a global satellite navigation system and provides a data set for DSRC remote query (Dedicated Short Range Communication). These devices are called second generation (G2) digital tachographs. Since the 2nd quarter of 2019, the first version (G2V1) of these tachographs has been installed. These are, for example, the DTCO 4.0 and the DTCO 4.0e, which has received some improvements and additional features via software update and, for example, supports the driver when entering the country when crossing the border.

Since August 21, 2023, the second version of the smart tachograph will be installed in new vehicles. The general abbreviation G2V2 has been established for this. VDO sells this tachograph under the designation DTCO 4.1 or since March 2025 under DTCO 4.1a.

This guide is intended for telematics service providers, tachograph workshops, and fleet managers.

The following describes the requirements that must be met to ensure smooth communication between the telematics unit and the VDO DTCO. 

Access from telematics units to DTCO to data
For installed fleet management systems, the DTCO offers four types of messages/protocols that FMS can use:

1. Cyclic CAN messages: The DTCO sends cyclic CAN messages such as time/date or VDO counter messages that can be read by an FMS
2. Diagnostic data
3. D8 info interface
4. Remote download data

List of abbreviations

DSRC: Dedicated Short Range Communication
DTCO: Digital Tachograph
ECU: Electrical Control Unit
FMS: Fleet Management System

ITS: Intelligent Transportation Systems
UDS: Unified Diagnostic Services (according to ISO14229)
UN: United Nations
UTC: Coordinated universal time

  In this guideline the term “telematics unit” and “fleet management system” are used interchangeably.

Introduction:

A digital or smart tachograph record driver activities as well as vehicle data. Data is stored on a driver card as well as in the mass memory of the tachograph. Local access to this data is possible through various interfaces, e.g. front interface, via Bluetooth (ITS interface) or CAN bus. However, data can also be accessed remotely in conjunction with a telematics unit which supports certain data protocols. In particular, remote download of driver card and mass memory is a very efficient procedure to archive data which is required from tachograph regulation point of view.

Data download from the individual driver card is required latest every 28 days (monthly) and the mass storage of the digital tachograph unit must be downloaded latest every 90 days (every quarter of a year).

Additionally, archived files must be held at the disposal of the authorities for a full year.

Moreover, fleet operators want to track vehicle data as well as driver activity data which is also feasible in conjunction with a FMS.

General overview

Overview on interfaces
Generally speaking, the DTCO provides wire bound as well as wireless interfaces in order to get access to vehicle and driver related data.

Data interfaces of a DTCO

CAN 1 is usually connected to the vehicle network, e.g. instrument cluster. CAN 2 is usually reserved for telematics units, but may also be used for tachograph related ECUs, like a CAN–DSRC module.
Moreover, the DTCO offers a (legacy) Info interface via pin 8 which provides a defined set ofparameters for FMS.
Data can be accessed wirelessly via Bluetooth ITS interface. This interface supports UDS as well as remote download (requires license).
Finally, UDS, local and remote download services are provided via the DTCO front interface.

Cybersecurity
Some vehicle manufacturers offer wire bound access to the DTCO only via a dedicated fleet management interface which is operated behind a security gateway. Avoid bypassing the security gateway as the Cybersecurity type approval of the vehicle may no longer be valid in this case.

Data interfaces

Security gateway in a vehicle architecture

Access to data
For installed FMS, the DTCO offers four types of messages /protocols FMS can make use of:

▪ Cyclic CAN messages: The DTCO sends out cyclic CAN messages like Time/Date or VDO counter messages which can be read by a FMS. Usually the number of parameters in cyclic messages is lower than data provided via UDS interface.
▪ Diagnostic data (UDS): The FMS has to actively request data and the DTCO responds to these requests. This is the preferred way to get access to detailed vehicle and driver related data.
▪ D8 Info interface: This is a legacy interface which will no longer be supported in future DTCO releases. The Info interface is a unidirectional interface, where the DTCO periodically broadcasts some fleet management related information (27 parameters in
total).
▪ Remote download data: Remote download is a peer to peer communication between a digital tachograph and a remote download terminal at the fleet company. The FMS acts
as a client and the DTCO as the server. In order to access remote download data, an authentication procedure in conjunction with the company card which is inserted in the remote download terminal is required. 
Note that remote download provides a secured link between the DTCO and the remote download terminal. In order to secure the other data, encryption/signing has to be carried out
by the telematics unit prior to data transmission to the Internet.

Recommendations for robust system design
▪ Avoid any authentication process close to and after UTC lunch time (12.00) and midnight (24.00/00.00)
Why?
The DTCO needs to perform - defined by legislation – a lot of different checks, especially self and cross checks in its memory and controller system. So please avoid any remote authentication or remote download at least 10min. before and 10 minutes after.
▪ Avoid multiple remote downloads per hour. Instead, if you want to download driver card data, make sure that you do not start the remote download process more than once hour. This ensures that the DTCO has sufficient time to complete a potential interrupted
download from a previous session.
▪ Do not install more than one telematics unit in the vehicle.
Why?
Both devices may not interfere each other which may lead to permanent authentication procedures. In the worst case this leads to either ejected driver cards while driving or blocked card ejections.
▪ Check if the vehicle has a dedicated fleet management interface which can be used to connect the external telematics unit to the vehicle network.
▪ Some vehicle manufacturers do not allow a direct connection of a telematics unit with a tachograph due to the vehicle Cybersecurity architecture. In the worst case, the vehicle may lose its Cybersecurity type approval and must not be operated on public roads. The respective regulation is UN R155.
▪ We strictly expect that any remote authentication will be closed after a successful download of data. We need to take care, that the vehicle battery capacity in the truck will not be unduly discharged and the DTCO can go into sleep mode.
▪ For track and trace as well as driver activity monitoring, do not use remote download function. Instead, use UDS commands (e.g. read data by identifier) or evaluate cyclic messages that are transmitted on the CAN bus.
Why?
Remote download is intended for archiving purposes, i.e. archiving driver card data as well as tachograph mass memory. A remote download requires a stable internet connection usually for more than 10 minutes.
▪ If possible, avoid any driver card download when vehicle is moving. 
Why?
When a DTCO driver card download is requested, the DTCO has to write and read the driver card. So, any side effect like vehicle vibration during drive or a longer disconnection, can influence the ongoing process and in the worst case result in an unforeseen card
ejection. Note: this does not have to be considered for any mass memory download.
▪ Train the drivers to keep the DTCO card slots clean and also avoid any dirt on the chip card contacts. Card cleaning kits can be found in the VDO web shop or at the VDO dealer.
▪ Avoid that a driver card is inserted for more than one week in a DTCO. Be sure that at
minimum once per week the card gets ejected in order to avoid any physical contact insulation.
▪ Make sure that data privacy is respected. Only if the (co-)driver has given his consent,data can be transmitted outside the cabin. DTCO provides parameters which contain the driver or co-driver consent information.
▪ No card can be ejected from the DTCO during a remote download. If a driver nevertheless requests his card, the tachograph responds with error code 34. This error code is only a user note and does not represent a device error.

Links: 
FMS Standard Website: https://www.fms-standard.com/Truck/index.htm

No, replacement is not necessary. For one, there is no legal obligation to replace them. Additionally, the DTCO 4.1 also fulfills all requirements with regard to the determination of position data or the automatic recording of border crossings. Therefore, if a vehicle has already been equipped or retrofitted with a DTCO 4.1, it may continue to be operated with this device.

From the summer 2025, a software update will be available to provide the DTCO 4.1 with the same functionalities as the DTCO 4.1a, including the OSNMA-authenticated Galileo position data.

In principle, all software-based functions of the G2V2 tachograph DTCO 4.1/4.1a can be adapted or changed via software updates, for which this is not prohibited by law. Examples of this would be an update of the digital map, the adaptation of the structures in a submenu or additional information for the driver in the VDO counter. We are therefore particularly interested in feedback from drivers and companies about existing potential for improvement. There are limits to adjustments made by an update, for example, in the case of functions whose modification would negatively affect protection against manipulation.

A good example of software-based adaptations, which meant an improvement especially for the drivers, is the update from DTCO 4.0 to the 4.0e version. The update provided the driver with suggestions for entering the country when crossing the border and additional information in the VDO counter that made it easier to comply with working time regulations. In addition, the DTCO 4.0e simply ejected the driver card ten minutes after insertion if no entries are made, instead of reading the card after one minute without manual additions, as it was the case with the DTCO 4.0. The smart tachograph of the second version DTCO 4.1 can also upgrade to the functions of the DTCO 4.1a with a software update without having to replace the whole device.

The processing and evaluation of the data stored by the tachograph offers fleet operators numerous opportunities to document legally compliant behavior or to react precisely in violations occur. The key to this is the VDO Fleet cloud solution. The data, which you either upload manually to our security servers or which is downloaded fully automatically from the tachograph's mass memory and driver cards via remote download, goes through an analysis process at the end of which compliance with numerous requirements has been checked. You receive vehicle and personal evaluations and can use the scorecards provided to see at a glance whether the regulations have been complied with or whether there is potential for improvement in driver or vehicle management. All data, documents and information are archived via the installation-free cloud solution.

Legally compliant transport handling is so important because the risk classification system means that a transport manager and, if necessary, other responsible persons in the company lose their personal reliability if too many or serious violations are committed during the execution of the transports. If personal reliability is in doubt or "revoked", there is a high risk of the continuation of the Community licence (EU licence).

For this reason, the reports and scorecards made available to you via the cloud platform VDO Fleet Tachograph Management not only show violations for driving, working and rest times, but also non-compliance with cabotage regulations and, in the future, also with posting regulations.

These services will also be available to fleets with older tachograph versions via the VDO Link, our plug-and-play device which is connected via the front interface of the tachograph. This is also available for fleets in which older tachograph versions are used.

With VDO Fleet and VDO Link, you take care of your business, we take care of your compliance.

The mass memory from the DTCO 4.(e) and the corresponding driver cards can be downloaded with a DLK Pro S. There will be a software update for the DLK Pro S for the DTCO 4.1/4.1a, which is available via our VDO portal. This software update enables the mass storage device to be downloaded from the DTCO 4.1/4.1a and Generation 2 Version 2 (G2V2) cards.

Older DLK Pro (without S), which have not yet been "upgraded" for Smart Tachographs, need a "DLK Pro License Card Smart TCO ready" in addition to the software update for DTCO 4.1/4.1a in order to be compatible with the DTCO 4.1/4.1a and G2V2 cards. This DLK Pro License Card Smart TCO ready has to be inserted into the DLK Pro once.

In addition, VDO launched a DLK Smart Download Key at the end of 2023, which can already download mass storage data of the DTCO 4.1/4.1a, G2V2 cards and all previous generations of the DTCO.

As an alternative to downloading the data via the 6-pin interface of the DTCO, the DLK Smart Download Key can also download the data from the DTCO 4.1/4.1a via the Bluetooth interface.

A major improvement for drivers carrying out cross-border transport is the fully automatic detection and storage of border crossings. This eliminates the need to stop at a suitable stopping place and manually enter the country via the tachograph menu.

Since the DTCO 4.1/4.1a can communicate via Bluetooth, it is possible to make entries or view evaluations via the VDO Fleet App. For example, manual supplements can be created more conveniently and a quick overview of the working and driving times already worked or the driving breaks and rest periods still to be taken can be obtained. The connection between the smartphone and the tachograph no longer requires additional hardware such as the DTCO SmartLink Pro. The scope of services and information provided by the app depends on whether you, as the driver, have consented to the transfer of personal data or not.

When you remove your driver card, the Bluetooth connection is disconnected. When the driver card is reinserted, the connection is re-established.

The special rules and innovations introduced by the EU Mobility Package I are integrated into DTCO 4.1/4.1a. This applies, for example, to the special rule in international freight transport, which makes it possible to take two reduced weekly rest periods in succession, or to extend driving time by up to two hours at the end of the working week in order to spend a weekly rest period at the place of residence or business location. If a weekly rest period is taken during transport in accompanied combined transport (ferry/train regulation), DTCO 4.1/4.1a also recognises this change from the EU Mobility Package I. In addition, all the improvements introduced with the DTCO 4.0e update will be carried over.

The DTCO 4.1/4.1a gives the driver a warning if the preset maximum speed is exceeded (usually 90 km/h). A warning is also shown on the display if the maximum permissible working time per day or per week is exceeded (>10 h/>60 h) or if a driver card expires about to expire.

The set UTC time is regularly compared with the time transmitted by the satellite positioning system and an adjustment is automatically made in case of minor deviations.

For the company, an advantage of communication via Bluetooth is that no additional hardware is needed to connect to the smartphone, tablet or other devices. The expense of purchasing the DTCO SmartLink Pro is eliminated with the DTCO 4.1/4.1a.

In addition, it is possible to download both the mass storage data and the data of an inserted driver card via Bluetooth when the company card is inserted. The VDO Fleet App can be used for this purpose. If the data is transferred in this way, a separate download key is no longer required. The VDO Fleet app is available for Android and iOS under the following links:

• iOS
• Android

The ITS interface of the DTCO 4.1/4.1a can be used to query and process data from the tachograph for telematics systems, regardless of whether the vehicle's ignition is on or off. The amount of data that can be queried cyclically or dynamically depends on the telematics system used and whether the driver has consented to the transfer of personal data.

Drivers also benefit from the fact that the DTCO 4.1/4.1a can communicate via Bluetooth. Via the VDO Fleet App, entries can be made or evaluations can be viewed. For example, manual supplements can be created more conveniently and a quick overview of the working and driving times already worked or the driving breaks and rest periods still to be taken can be obtained. The connection between the smartphone and the tachograph no longer requires additional hardware such as the DTCO SmartLink Pro. If you do not consent to the transfer of personal data, the scope of services of the app or other applications may be limited.

VDO and our VDO partners offer various training courses for drivers, fleet operators and workshops:

The requirements for Gen1 and Gen2 V1 driver cards were set some years ago and at that time it was not foreseen to store border crossings on these cards. Therefore, border crossing information is not available on the daily printout of these driver cards. However, the DTCO 4.1/4.1a stores border crossings in the mass memory, so they can be displayed on the vehicle's daily printout.

The devices known as transition tachographs also record border crossings fully automatically. The driver, with a DTCO 4.1, only has to enter the country manually at the beginning and end of the daily working time and create the supplements for the times away from the vehicle.

Even if only an "OSNMA test signal" is available during the transitional period, the DTCO 4.1 will mark the data as secure. This can be seen, for example, on a printout via the pictogram that symbolizes a closed padlock.

The EU legislator has stipulated that the DTCO 4.1/4.1a must work with the position and time data of the Galileo satellite system. This system offers the so-called OSNMA (Open Service Navigation Message Authentication) service, which has the function of "testifying" the authenticity of the position and time data, thereby establishing a high level of protection against manipulation.

At the time of the launch of the DTCO 4.1, this system was not yet available in the final version. It is expected that there will only be a test signal until mid-2025 with which the new tachographs will also largely fulfil the legally prescribed functions.

For drivers and companies, this deviation has no effect on day-to-day operations. After the OSNMA service is fully available, it will be possible to upgrade the DTCO 4.1 to the DTCO 4.1 a with full OSNMA functionality via a software update. This update will not be mandatory – however, due to legal requirements, it may be necessary to make an update, e.g. if the map material changes. Software updates can be made in connection with a planned workshop visit.

The legal basis does not result in an obligation to integrate this query into the registration and deregistration process when inserting and removing the driver card. With the DTCO 4.1/4.1a, this information is not automatically requested each time the driver card is entered or removed, since it cannot be assumed for every driver at this point in time that loading or unloading or the boarding or alighting of passengers will be involved.

If the DTCO 4.1/4.1a has already been activated and the vehicle is being towed or transported, the ferry/train setting must be activated. This is necessary to avoid the message "Movement Conflict".

As of DTCO 4.1, the ferry/train setting must generally be activated for every ferry/train crossing (even for short crossings) in order to avoid the message "Movement Conflict".

This amendment corresponds to the currently valid version of Regulation (EU) 2016/799 (21/08/2023).

The ferry/train recording will be finished as soon as:

• Ferry/train is deactivated in the menu,
• the driver card is removed or
• the vehicle drives for at least one calendar minute.

It is therefore essential that you check at your final position during shipment whether the ferry/train setting is active or whether the ferry/train pictogram is visible in the DTCO 4.1/4.1a display.

Since May 21, 2022, anyone who transports goods across borders for a fee with vehicles or towing vehicle-trailer combinations with a maximum permissible mass of more than 2.5 t or who carries out cabotage transport requires a permit under road haulage law, the so-called EU license. Cabotage transport is transport carried out within a country in which the carrier has no place of business, for example, a transport by a German carrier between Warsaw and Gdansk in Poland.

From July 1st, 2026, the obligation to have a 2nd version smart tachograph (G2V2), for example a DTCO 4.1 or DTCO 4.1a, installed in the vehicle will also apply from the "more than 2.5 t limit" for cross-border transport and cabotage transport. Vehicles that cannot be equipped or retrofitted with a corresponding tachograph may not be used for such transport (from July 1, 2026).

In Germany, as of April 2025, it is still unclear which wording will be used to adapt the national legal basis (Driving Personnel Act and Drivers' Ordinance) to the EU law amended by the EU Mobility Package I. Only after the amendment of these legal bases will it become clear whether freight carriers based in Germany will also use tachographs to record carriage that takes place exclusively on the territory of the Federal Republic of Germany with vehicles between more than 2.5 t and no more than 3.5 t maximum permissible mass have to make. As of May 2023, goods transport for third parties for a fee in Germany with a maximum permissible mass of more than 2.8 t must be recorded (by "daily control sheet" or by tachograph, if one is installed), unless an exception under paragraph 1 or 18 of the driving personnel ordinance applies.

As the DTCO 4.1/4.1a must also be able to store an increased amount of additional or extended information on the driver card, new driver cards (Generation 2 Version 2, G2V2 for short) have been issued since July 21, 2023 for new or replacement applications. These can, for example, store up to 1,624 loading and/or unloading processes as well as many other data sets that cannot be recorded at all on G2V1 driver cards. G2V2 driver cards are downward compatible with older digital tachographs and therefore also work in a DTCO 2.2a or 3.0(a) for example.

A mandatory exchange of valid driver cards is not required by law in Germany. An existing driver card can therefore be used until the end of its validity. The DTCO 4.1/4.1a can also "work" with older driver cards (G1 or G2V1 driver card).

As from December 31, 2024, the period of time that must be documented or carried has been extended to the current day and the preceding 56 calendar days, you as a driver should not forget that after the expiry date you should not carry your old driver card for a further 28 days, as before, but for a further 56 days.

The border crossings are stored on the new G2V2 driver cards and are therefore visible on the daily printout. In addition, border crossings are also visible on the vehicle's daily print out.

The DTCO 4.1/4.1a or all G2V2 tachographs only accept second-generation workshop cards. Since these G2 workshop cards were introduced a few years ago and the workshop cards have to be renewed annually, there are no longer any valid G1 workshop cards in the EU member states. This means that you can use the existing workshop card until the end of its validity.

In the case of checks by authorities, drivers do not have to fear a penalty for a violation. It is purely a device anomaly, not a driver error.

The control authorities were informed by Continental/VDO about the anomaly and its cause.

It is important for you as the vehicle operator with an affected tachograph to know:

• The warning message does not have any serious consequences.
• The message does not affect the functioning of the device. The DTCO 4.1 does not need to be replaced. The issue also does not render the tachograph applicable for a complaint.
• In principle, all data is stored in the device. The technical data can be printed out in full. There are only restrictions in the download of the technical data. The tachograph continues to meet the legal requirements.
• All driving and rest periods are duly stored.

In summary: Apart from the fact that the messages "Error 25" and "Event 15" are stored and can be viewed, there are no effects.

When entering the vehicle registration number and the country of registration with the company card on a DTCO 4.1, the following effects will occur:

1. When downloading the technical data block, calibration purpose 5 is missing. In addition, an inconsistent signature is provided for this block of data. This can cause issues with some of the download tools available in the market.
2. When printing the technical data for the first time, the message "Error 25" will occur. In the printout, the message "Error 25" corresponds to the message "Event 15". The message "Error 25" only occurs on DTCO 4.1 and only if the vehicle registration number and country of registration have been entered with a company card. The message "Error 25" does not occur if the vehicle registration number and the country of registration have been entered with the workshop card.

Note: The message does not affect the functioning of the device. All data is stored in the device.

When entering the vehicle registration number and the country of registration with the company card on a DTCO 4.1, the following effect will occur:

When downloading the technical data block, calibration purpose 5 is missing. In addition, an inconsistent signature is provided for this block of data. This can cause issues with some of the download tools available in the market.

All VDO download tools and archiving solutions will perform the download of the complete data despite this inconsistency in the signature.

Under certain circumstances, a fleet may experience interference when using the download tools of other providers. Download tools from other providers will sometimes refuse the download of data from the mass storage completely. Continental/VDO has informed the manufacturers of download solutions as far as they are known. In case of malfunctions, please contact the provider of your download tool.

Note: By downloading the overview block, the license plate number and the country of registration are still included in the downloaded data. Thanks to the signature of the overview block, it is still possible to unambiguously assign the tachograph to the vehicle.

When entering the vehicle registration number and the country of registration with the company card on a DTCO 4.1, the following effects will occur:

1. When downloading the technical data block, calibration purpose 5 is missing. In addition, an inconsistent signature is provided for this block of data. This can cause issues with some of the download tools available in the market.
2. When printing the technical data for the first time, the warning message 25 will occur. In the printout, message "Error 25" corresponds to the message "Event 15".
   The message "Error 25" only occurs on DTCO 4.1 and only if the vehicle registration number and country of registration have been entered with a company card. The message "Error 25" does not occur if the vehicle registration number and the country of registration have been entered with the workshop card.

Note: The message does not affect the functioning of the device. All data is stored in the device.

If the vehicle registration number and the country of registration are entered with a workshop card before the DTCO is put into operation for the first time, the issue with the inconsistent signature of the technical data block will not occur. In this case, there are no consequences whatsoever.

If the end customer entered information on vehicle registration number and country of registration using a company card,

If the end customer entered information on vehicle registration number and country of registration using a company card, you should avoid printing of the tachograph technical data for the time being to avoid message "Error 25".

Note: In day-to-day fleet operations, a printout of the technical data is not necessary and is not required by law. The occurring of the message "Error 25" is only produced once through the printout.

The message itself does not have any problematic effects for fleets, as all data is still correctly available in the mass storage and can be retrieved in principle.

However, depending on how a download tool is set up by the manufacturer, it can happen that the download tool completely blocks the download of data from the tachograph's mass storage due to the message "Error 25".

Providers of download tools can remedy this by increasing the error tolerance during the download and thus allowing the data from the mass storage to be downloaded despite the message "Error 25".

A more detailed description and further information for programmers has been summarized by Continental/VDO in a technical information.

The message "Error 25" will be downloaded and archived. However, this has no concrete impact on everyday fleet life. The control authorities were also informed by Continental/VDO about this issue and its origin.

These anomalies have been resolved for DTCO 4.1a devices available since March 2025. For all those who have already equipped or retrofitted their vehicles with a DTCO 4.1, a software update will be available from summer 2025, which will solve this issue. You will receive further information on this during your next visit to a VDO partner workshop.

The EU regulation states that all driving times of a driver must be documented without gaps – preferably on the driver’s card. If this is not possible, a driver must carry a confirmation (EU form) from the company covering the last 28 days before he starts the trip.

The calculation of the times is done using fixed parameters, which are defined in the EU regulation – irrespective of the digital tachograph’s manufacturer.

Article 34 (7) of the EU regulation No. 165/2014 stipulates the following: “The driver shall enter in the digital tachograph the symbols of the countries in which the daily working period started and finished.” So yes, it’s necessary to enter the country symbol at the start and end of your daily work period even if the country has not changed and/or the driver card remained in the device overnight. The legal requirements do not suggest any rule according to which a country symbol only has to be entered if the country has changed.

A driver card with an expired validity date will no longer be accepted by the tachograph. The “Card invalid” error message will appear in the display and the card will be ejected. This also means that no further data will be saved on the expired card. In this case, the driver or the company must apply for or purchase a new card from the card-issuing body which is responsible.

This message means that the driver card or mass memory download is due, hence the “0 days” in the display.

An authorised workshop can program the DTCO so that this message appears in the display a few days beforehand.

So you must read out the driver card and/or the mass memory of the digital tachograph.

The driver card must be read out at least every 28 days and the mass memory data at least every 90 days.

You’ll need a company card and a driver card to operate the tachograph properly.

You can apply for these cards either at your local trade office or at vehicle registration and technical inspection authority offices.

The first step is to register the tachograph with the company card.

Make sure you have enough printer paper rolls in the vehicle.

You must also comply with the regular intervals that are prescribed for checking the device, meaning you must visit an authorised tachograph specialist workshop every 2 years.

Tachograph repairs and calibrations may only be carried out by authorised specialist workshops.

You can usually find relevant information in the operating manual, which must always be in the vehicle. If you don’t have this manual, we recommend that you purchase one from our dealers or a specialist workshop.

For reading out the driver cards (every 28 days at the latest) and the mass memory of the digital tachograph (every 90 days at the latest), we recommend our current DLK Pro Downloadkey with the article number A2C59515252. It contains an integrated card reader for reading out driver cards. If you have this key, you don’t need a licence card to unlock the integrated card reader.

However, the key only reads out and archives the data – you can’t display and evaluate any data with it.

Our TIS-Web Data Management online solution is ideal for evaluating driver and vehicle data.

The monthly fees for this depend on the number of vehicles and users recorded and the range of functions used, which can be flexibly selected in various user levels.

All you have to do is transfer the vehicle and driver card data to the TIS-Web platform. The data is then backed up in a professional data centre.

We do not offer access to TIS-Web in our webshop. We recommend that you contact one of our specialist dealers for this.

We can offer you our DLK Pro TIS-Compact (article number A2C59515262) as an alternative here. It’s almost like the DLK Pro Download Key, because if you have it, you don’t need a licence card to activate the integrated card reader. However, the difference is that the DLK Pro TIS-Compact is restricted to a fleet of up to 5 vehicles and up to 10 drivers. This key also differs from the normal DLK Pro in that it contains software you can install on your PC or laptop. This means you can store the data locally on your computer and also display and evaluate it. If you decide to use the DLK Pro TIS-Compact, you don’t need additional TIS-Web access.

The buffer batteries in the digital tachographs must be replaced every 2 years as part of the periodic DTCO tests.

This ensures that the digital tachograph is not damaged. The DTCO must continue to safely store the data for 1 year after disconnection from an external supply voltage (e.g. the vehicle battery).

If the buffer batteries are not replaced every 2 years, there is a risk that they will discharge. This means that the data stored in the DTCO will be irrevocably lost and the DTCO will no longer function.

The only thing you can do then is to replace the device.

One special feature of the DTCO 1381 Release 2.1 is the integrated VDO counter, which shows the remaining driving and rest times in real time on the device’s display.

Please note that the VDO counter function of the DTCO Rel. 2.1, which is directly installed by the vehicle manufacturer ex works, must be activated with an additional DTCO VDO Counter Update card.

The VDO counter is already enabled in our “DTCO 1381 Rel. 2.1 active” retrofit devices. If you have this release, you don’t need an update card.

“Out of Scope” mode means that the vehicle is travelling outside the scope of the regulation. This is possible for trips outside EU countries, for example, and may also be possible for trips on non-public roads. However, it may be open to interpretation and it is sometimes evaluated differently from state to state. As the manufacturer of the tachographs, we cannot make any legally binding statements in this case. We highly recommend that you contact your trade supervisory authority.

It is of course possible to replace the DTCO in your vehicle with a new device. Depending on the vehicle type, a vehicle-specific version can be used if necessary, or alternatively, you can use a “Universal DTCO”, which is then parameterised accordingly.

In any case, this work must be done by an authorised tachograph specialist workshop.

You can find suitable specialist workshops here. 

The DLK Pro Download Key S will remain in the VDO portfolio alongside the DLK Smart Download Key. The DLK Pro Download Key S is the basic version of the download tools. The DLK Smart Download Key is the premium version.

No. The DLK Smart Download Key is already "ready" for the DTCO 4.1 and the corresponding tachograph cards.

All versions of the DTCO from version 1.x to 4.1 can be downloaded with the DLK Smart Download Key. This also includes the tachograph cards of the various generations (Gen. 1, Gen. 2V1 and Gen. 2V2). In addition, the DLK Smart Download Key is also compatible with authorised digital and intelligent tachographs from competitors.

The DLK Smart Download Key can automatically transfer the downloaded data via Bluetooth to the VDO Fleet App on the mobile phone*. From there, it is possible to transfer the data to the customer's VDO Fleet account, where it can be archived and analysed. The VDO Fleet App will be available in January 2024.

It is also possible to automatically upload the data to the VDO Fleet Portal* using the PC application KeyTools via the "DLK Automatic Uploader" of the DLK Smart Download Key.

* A VDO Fleet Tachograph Management licence is required for automatic data processing and archiving.

The DLK Smart Download Key is not limited to a specific number of drivers or vehicles. The available memory is also sufficient for several thousand downloads.

If you already have a DLK Pro Download Key S, you can download free updates from our customer portal myVDO to keep your DLK compatible with the latest tachographs: Dashboard (vdo.com)

Since the interface of the digital tachograph is technically defined by EU regulation, the speed of the data download can only be influenced to a limited extent, as this interface does not generally permit fast data transmission.

Question:
I have no data from the truck during a certain period, but the driver card data is read out correctly. I use the DLK Pro. Why?

Answer:
1) Do you also regularly load the mass memory from your digital tachograph into your archiving software? If not, then it’s possible that only certain sections are taken from the mass memory data for reporting purposes, depending on the archiving software. If only data from the driver card is downloaded, that is insufficient and does not comply with the legal requirements.

2) If only some of the vehicle data is missing (gaps), then this may be due to the following reasons: Because the download key is set to “Since the last download” by default, only the (vehicle) data that has been added since the last download is downloaded. If the (vehicle) download is now interrupted for any reason (accidental removal, etc.) then the download key notes the date of the download but the interruption prevents it from downloading any data – so data will be missing. When data is downloaded again, then only the most recent data is requested (since the last download, even if this was defective). However, the old, missing data will no longer be downloaded.

The solution:
Set DLK Pro to “entire mass memory” (Workplace/Keytools/Start.exe) and repeat the download. When the download has completed, all the data should be available again. You can then set the DLK Pro back to “Since the last download”. It also downloads more quickly with this setting.

Question:
We’re interested in the DLK Pro Download Key. Is there any limitation on the number of vehicles and drivers that can be downloaded? Eight vehicles and 14 drivers can currently be downloaded. At present, we use an older VDO download stick + card reader to send our data in ddd format to an external company for evaluation and archiving. Can we carry on doing this with the DLK Pro?

Answer:
The DLK Pro Downloadkey has no limitation in terms of drivers and vehicles, it’s only the amount of memory that’s limited. You can use the “new” Downloadkey in the same way as the older one, but a card reader is already integrated into the newer version. Only the DLK Pro TIS Compact is limited – but only in the evaluation function (5 vehicles, 10 drivers), not with the download itself. If you want to send the driver’s card or vehicle data automatically, we recommend our Remote Download Device DLD. The DLD system gets the data into the office 100% automatically, so you won’t have to chase after your drivers or vehicles for information if you use this system.

Question:
I have several trucks. In the case of one vehicle, it’s vital that I get all the tachograph data. The truck has been with me since September 2014, but the UN card was apparently not inserted until February 2016. Right now I can only read the data from today to February 2016. Is there any way to get the “missing” data (September 2014 - February 2016)?

Answer:
If your company card was inserted into the digital tachograph for the first time in February 2016, the data should also be downloadable before the company lock was set in February 2016 (free data). However, from the information you’ve given us, we believe that another company must have already been registered before that – so you can’t download this data with your company card. An authorised workshop can download all the data using its workshop card, but it’s only allowed to release the free data (without a company lock) and the data protected with your company lock to you.

Question:
I have the VDO Download Key DLK Pro to read out the tachograph data. When I plug the DLK into the tachograph in the truck, it takes about 15 minutes, then it lights up green. So far, so good. But when I insert the driver’s card in the DLK, I get a “No Authorization” message. I also can’t view driver activity on my PC. I can see that something has taken place on this date, but nothing more. Do I need additional software for this and is it mandatory? Is this readout process correct and sufficient?

Answer:
You obviously have a download key that hasn’t been unlocked yet. It was not automatically included from the outset, but was activated via an additional activation card. The current versions already have this included. From March on, there will probably be an update in which the DLK Pro card readers that have not yet been activated will be activated free of charge. However, it’s mandatory to read out the driver card as well. Depending on the archiving software, this can also be downloaded using an additional card reader (external USB). Alternatively, the download key can also download the driver card while downloading the mass memory (here the driver card must also be inserted in the digital tachograph and the driver card download must be enabled in the DLK settings). In all cases, the data is archived and evaluated using archiving software (e.g. TIS-Web). Simply downloading the data does not comply with legal requirements.

To use the app, a DTCO® version 2.0a or higher, the DTCO SmartLink Pro and a smartphone with Android or iOS are required.

The use of the app is free of charge, as long as the necessary hardware is available. The VDO SmartLink Pro can be ordered on DTCO® SmartLink Pro (Android + iOS) |VDO online shop (vdo-shop.com).

The connection is made via Bluetooth. After successful pairing, the main menu (the three dashes in the upper left corner of the image) will take you to the option "Connect SmartLink" This requires the six-digit PIN, which is visible on the label of the SmartLink. After that, only the DTCO token (visible on the DTCO display) has to be entered.

It is recommended to eject the driver card in advance by remote control. Then, all corresponding activities can be entered in the menu via the "Manual supplement" option. As soon as the tachograph is ready to receive the data, it switches to transmission mode.

The calendar is downloaded via the "Driver activity" function and shows driving times, rest times, other activities, on-call times as well as distances traveled.

The upper half of the screen of the main menu shows the remaining driving time until the next break. The "VDO Counter" function provides more details.

The last activities can be seen in the sub-tabs of the VDO counter: these are driving time, rest time and history. Driving data and a rest time register are also available. Under "History" you will find daily and weekly data.

In the VDO Counter menu, the desired activity can be set under "Daily" and then under "Change activity".

First, the connection to the DTCO must be allowed under "Driver entry" and "Remote/remote control". The current connection status can be viewed in the app under "Setting" and then under "Diagnostics".

Under VDO Fleet - Downloads you will find a detailed description in different languages.

The app support email address is app-support@continental.com.