Abstract: An assembly has a tachograph and a data memory, in particular a data memory of a data card. The tachograph has an interface designed to exchange data between the tachograph and the data memory, logic function modules and at least one memory. In a method for operating the tachograph, as a result of high security requirements, the data transfer between the data memory and the tachograph is extremely time-intensive. At the start of the data transfer a virtual reproduction of the data memory is created in the memory of the tachograph and the logic function modules first have read and write access to the virtual reproduction in the memory. Data is then regularly written to the data memory of the data card by a write access to the memory, thus eliminating the differences between the virtual reproduction and the data memory.

Abstract: An assembly has a tachograph and a data memory, in particular a data memory of a data card. The tachograph has an interface designed to exchange data between the tachograph and the data memory, logic function modules and at least one memory. In a method for operating the tachograph, as a result of high security requirements, the data transfer between the data memory and the tachograph is extremely time-intensive. At the start of the data transfer a virtual reproduction of the data memory is created in the memory of the tachograph and the logic function modules first have read and write access to the virtual reproduction in the memory. Data is then regularly written to the data memory of the data card by a write access to the memory, thus eliminating the differences between the virtual reproduction and the data memory.

Abstract: In a method for exchanging data between a tachograph (DTCO) and a terminal device (CALTEST), the data transmission protocol provides for the terminal device (CALTEST) to cause the tachograph (DTCO) to perform a service by indicating at least one service identification (SID). The method further provides for transmitting data in such a way that a flexible compatibility of the tachograph is obtained. The tachograph (DTCO) encompasses an allocation of internal service identifications (IIDS) to external service identifications (EIDS), the external service identifications (EIDS) are used during data exchange with the terminal device (CALTEST), and external service identifications (EIDS) of incoming data are exchanged with matching internal service identifications (IIDS) according to the allocation (mapping list MAP) by a communication module (COMM).

Abstract: The invention relates to a method for secure data transmission, particularly between a tachograph (51) in a commercial vehicle and memory cards (50), where a first subscriber (T1) has a memory (6, 22) with entries (31-35) comprising identifiers (4) and security certificates (Cert) from second subscribers (T2). Methods for secure data transmission are becoming increasingly important and are frequently associated with a high level of computation complexity. For this reason, the object of the invention is to reduce the computation time for this without security losses. It is proposed that the first subscriber (T1) fetch an identifier (4) from the second subscriber (T2) and compare it with stored identifiers (4). If the identifier (4) matches, a security certificate (Cert) associated with this identifier (4) is the basis for a subsequent data transmission, and if the identifier (4) does not match then security certificate verification is performed.