In order to allow any downloading of data from any Vehicle Unit (VU) using an Intelligent Dedicated Equipment (IDE), the technical protocol and procedures to download data from a VU to an IDE have been standardised and specified in Annex 1B to Regulation (ECC) n°3821/85 (Appendix 1B to the Annex to the AETR).
Annex 1B to Regulation (ECC) n°3821/85 gives the following definition of “Downloading”:
“Copy of a part or of a complete set of data stored in the data memory of the vehicle or in the memory of the driver card. Downloading may not alter or delete any stored data. Downloaded data are protected in such a way as to make attempts to data manipulation detectable; origin of downloaded data must be authenticable. Downloaded data are kept in a format that can be used by any authorised person”.
General downloading procedure
The VU allows data downloading only in Calibration mode, Control mode or in Company mode. The download protocol is structured on a master-slave basis, with the IDE playing the master role and the VU playing the slave role. In order to carry on a VU data download, the operator must perform the following operations:
- Insert a control card or a company card in the VU,
- Connect the IDE to the VU download connector (external interface),
- Establish the connection between the VU and the IDE,
- Select on the IDE the data to download and send the request to the VU,
- Close the download session.
The result of one download session is one physical file in the IDE.
Establishing the connection between the VU and the IDE
When the IDE and the VU are physically connected, they exchange technical messages in order to start the communication link and agree on a communication speed (baud rate).
The operator will then press on the IDE a button to start the download session. The VU respond to this request with the following data:
- Vehicle Identification (VIN, VRN, Registering Member State),
- Oldest and most recent dates of activity data held in the VU data memory,
- Last company download date with company identification,
- Company locks (dates and company identification of lock ins and lock outs),
- Previous controls (law enforcement) with dates, control card number, type of control and downloaded periods.
These data when presented on the screen of the IDE help the IDE operator (whether from a company or a law enforcement authority) selecting which set of data he wishes to download and for which period.
Selecting data to download on the IDE
Four choices are then be presented to the IDE operator:
- Download driver activities between two calendar dates (typed by the operator),
- Download events and faults data,
- Download detailed speed over 24-hour data,
- Download technical data.
Once the data chosen have been downloaded (with their digital signature), the operator may re-select another choice of data to download or close the download session.
Closing the download session
When pressing the close download session button, the IDE stores within its memory all the data received since the beginning of the session and stop the communication. The VU records in its memory the necessary data about the download session.