Title of Invention	A SYSTEM WITH A TACHOGRAPH AND A DATA STORE FOR DATA INTERCHANGE BETWEEN THE TACHOGRAPH AND THE DATA STORE
Abstract	A system (1) having a tachograph (DTCO) and having a data store (13, 14), particularly a data store (13, 14) on a data card (4, 5), where the tachograph (DTCO) has an interface which is used for data interchange between the tachograph (DTCO) and the data store (13, 14), which tachograph (DTCO) has logic functional modules (FM) and at least one memory (DMEM) and the logic functional modules (FM) are in a form such that at the start of the data transmission a virtual map (VI) of the data store (13, 14) is first of all created in the memory (DMEM) of the tachograph (DTCO), subsequent read and write access operations by the logic functional modules (FM) are first of all effected on the virtual map (VI) in the memory (DMEM), and a write operation is regularly effected by accessing the data store (13, 14) on the data card (4, 5), during which the differences between the virtual map (VI) and the data store (13, 14) are aligned, characterized in that the regular read and write access is effected at periodic intervals of time and/or when a particular volume of data needs to be aligned between the virtual map (VI) and the data store (13, 14) on the basis of changes in the map.

Title of Invention

A SYSTEM WITH A TACHOGRAPH AND A DATA STORE FOR DATA INTERCHANGE BETWEEN THE TACHOGRAPH AND THE DATA STORE

Abstract

A system (1) having a tachograph (DTCO) and having a data store (13, 14), particularly a data store (13, 14) on a data card (4, 5), where the tachograph (DTCO) has an interface which is used for data interchange between the tachograph (DTCO) and the data store (13, 14), which tachograph (DTCO) has logic functional modules (FM) and at least one memory (DMEM) and the logic functional modules (FM) are in a form such that at the start of the data transmission a virtual map (VI) of the data store (13, 14) is first of all created in the memory (DMEM) of the tachograph (DTCO), subsequent read and write access operations by the logic functional modules (FM) are first of all effected on the virtual map (VI) in the memory (DMEM), and a write operation is regularly effected by accessing the data store (13, 14) on the data card (4, 5), during which the differences between the virtual map (VI) and the data store (13, 14) are aligned, characterized in that the regular read and write access is effected at periodic intervals of time and/or when a particular volume of data needs to be aligned between the virtual map (VI) and the data store (13, 14) on the basis of changes in the map.

Full Text	FIELD OF THE INVENTION The invention relates to an arrangement having a tachograph and having a data store, particularly a data store on a data card, where the tachograph has an interface which is used for data interchange between the tachograph and the data store, which tachograph has logic functional modules and at least one memory. BACKGROUND OF THE INVENTION In line with EC regulation No 3821/85, in future the tachographs used in commercial vehicles to record operating data will no longer, as conventionally, use analogue means to write on a paper tachograph disk but rather will store the speed over time digitally in a data store, namely a data store on a data card. The EC regulation contains extensive details as to how the data to be recorded, which need to meet the requirements for legal evidence, inter alia, are to be stored and to be protected against manipulation. To meet the stringent requirements of the regulation, very complex cryptological protection mechanisms and authentication processes need to be implemented. Particular focus in this context is on allowing the transmission of data between the data store on the data card and the tachograph. A data card holding apparatus is already the subject matter of German laid-open specification DE 103 21 252 Al, which describes an antimanipulation holder for a card in a tachograph as described above. Particularly the transmission of data between the data store on the data card and a memory in the tachograph needs to be protected against manipulation, since experience shows that such attacks are to be feared in this area. For this reason, pertinent tachographs and data cards respectively provide an encryption unit as an integral component which is used to transmit data in cryptologically protected form exclusively using a session key. This protection is extremely complex, however, and requires a lot of patience from the user, since access times are extended almost intolerably on account of the protection of the data transmission between the tachograph and the data card. In line with ISO 7816, the read/write access to the data store on the data card is furthermore limited to a length of 256 bytes, which means that the communication via the serial connection used at this location takes place very slowly on the basis of the EC regulation. DE 195 33 515 Al discloses a tachograph arrangement. A driver's card has a nonvolatile overrideable memory for storing control data. The tachograph arrangement has a device for writing control data to the memory on the driver's card and for reading the control data stored in said memory. A temporary control data store and a control device are provided. The control device controls the operation of the tachograph arrangement such that when the driver' s card is inserted into the tachograph the control data stored in the driver's card are loaded into the temporary control data store, are updated in the temporary control data store while the driver's card remains in the tachograph, and the updated control data are loaded into the control data store of the driver's card when said driver's card is removed. Control data are secondary data which are obtained by further processing of primary data relating to the operation of driving, particularly by means of addition over time. The secondary data contain relevant information about the working time regime. GB 2 271 180 A discloses an electronic tachograph with a vehicle position-finding unit. The tachograph has a central processing unit and a memory to which the processing unit has direct access. The processing unit also uses information from a removable memory card which is associated with the driver or co-driver. The memory card sends information such as the identity of the driver and driver parameters. The information received from the memory card is held in the tachograph's memory. The memory also contains outputs from the processing unit which are supplied to the memory card. OBJECT OF THE INVENTION Against the background of the prior art, it is an object of the invention to shorten access times when dealing with the tachograph without losses of security, or particularly in respect of the communication between the tachographs and the data card. SUMMARY OF THE INVENTION To achieve the object, it is proposed that the logic functional modules be in a form such that at the start of the data transmission a virtual map of the data store is first of all created in the memory of the tachograph, subsequent read and write access operations by the logic functional modules are first of all effected on the virtual map in the memory, and a write operation is regularly effected by accessing the data store on the data card, during which the differences between the virtual map and the data store are aligned. In this context, the regular read and write access is effected at periodic intervals of time and/or when a particular volume of data needs to be aligned between the virtual map and the data store on the basis of changes in the map. One particular advantage of the invention is the saving of a large number of data transmission cycles between the tachograph and the data store or the data card. Since pertinent tachographs regularly have two holding apparatuses for two data cards, the saving of this complexity has almost double the effect. Since the regularly interrupt-controlled recording signals from the speed sensor, which queue up at a high frequency, mean that the tachograph's processing unit utilizes the central processing unit to a relatively high degree during operation, the load relief based on the invention is a great advantage. Regular alignment can take place comparatively rarely, for example at intervals of 12 hours in each case. In the event of a request to remove the data card from the tachograph or when the data store is separated from the tachograph, alignment is necessary between the virtual map in the memory and the data store on the data card. The request for removal is regularly made when the commercial vehicle is at a standstill, however, which means that the high-frequncy speed signal is not queuing and the central processing unit is relieved of load anyway. This allows acceptable access times to be implemented despite the necessary alignment when the data store is separated from the tachograph. As an alternative or in addition to regular read and write access to the data store, particularly the data card, by the tachograph at periodic intervals of time, preferably every 12 hours, such data interchange can also take place when a particular volume of data needs to be aligned between the virtual map and the data store on the basis of changes in the map. A minimum standard which would nevertheless satisfy pertinent security provisions is the option of aligning the virtual map with the data store before the data store is separated from the tachograph. Advantageously, the tachograph is in a form such that the data card is held completely by the tachograph's data card holding apparatus and cannot be removed from the appliance directly, but rather the user communicates a removal request to the appliance by pushing a button, whereupon the data card is ejected from the tachograph following an appropriate interchange of data. Although a modern tachograph is regularly already provided with all the security mechanisms possible from a mechanical point of view which protect the data transmission between the data store and the tachograph against manipulation, the data transmission between the data store and the tachograph regularly takes place in encrypted form. The data store is used to record particularly the speed data from the commercial vehicle and the activities of the vehicle driver. In this regard, the available storage space on the data card is relatively limited, which means that a portion of the data store is expediently in the form of a ring memory and in this way the oldest recordings are always overwritten with the most recent. Taking this into account, the map of the ring memory may advantageously be in the form of a linear memory, with a start address for the first entry and an end address for the last entry, where a stipulated addressing order provides for the call to the end address to be followed by the call to the start address. In this context, it is expedient if, although the virtual map of the data store maps the architecture of the data store, the data stored in the ring memory are mapped in the map only in part. Full transmission of the entire content of the data store, for example when the card is inserted into the tachograph, sometimes takes an unacceptably long time, the old data not necessarily having any corresponding practical benefit in this context. It therefore makes sense if the virtual map, following initial production, first of all maps only the data from the last entry block in the ring memory of the data store. To avoid excess complexity for the data transmission, it makes sense if the virtual map has at least one associated change pointer, namely the data store of the tachograph stores the location of the virtual map of the ring memory at which the first change since the last alignment was made. In one advantageous development of the invention, a write operation in the virtual map extending from the end address to the start address of the map involves at least one change pointer marking the location in front of the end address at which the changes after the last alignment have started and at least one second change pointer marks the location at which the write operation was continued after the end address. Such marking over the address jump in the ring memory ensures conflictless alignment between the data store and the memory of the tachograph. The reliability of this operation can be additionally increased if the change pointers additionally also comprise information about the number of bytes which have been stored in the ring memory starting from the indicated location since the last alignment. A lot of time may be lost when various logic functional modules effect read or write access to the map and fixed time windows have been prescribed for this. Although such operations may also be carried out under interrupt control, this destabilizes operations in the central processing unit. It is therefore particularly expedient to coordinate the logic functional modules effecting read or write access to the map using a central status variable. In this context, it makes sense if the functional modules regularly request the status variable and, when the status variable has a particular value which is associated with the respective requesting functional module, initiate queuing write operations. As a ready message, so to speak, provision may be made for the logic functional modules which carry out the write access operations on the memory area of the map to change the status variable following the conclusion of the queuing tasks. Conflictless coordination of these access operations on the data store is assured particularly if the logic functional modules comprise a map status module which regularly retrieves the status variable and allocates it a new value if another functional module has previously changed the value, which new value is associated with a particular functional module for the purpose of allocating the write access. The invention provides particular runtime advantages if the functional modules comprise an encryption unit which is used to encrypt elements of the data transmission between the tachograph and the data store. To this end, the data store may likewise have an encryption unit. On the basis of the special inventive marking of the data from the virtual map which are to be aligned, the invention provides further advantages when the electrical power supply fails. In this case, the arrangement may provide that when the power supply has failed, any other access to the data store is first of all preceded by identification data from the data store being compared with those from the virtual map of the data store. This configuration makes sense because, when the supply voltage is cut off, an attempt at manipulation may possibly provide for the data store to be replaced. The advantage of the invention at this junction is particularly that the virtual map of the data store, including the identification data, is already available and hence merely a comparison is necessary. If a power failure occurs directly before a data transmission commences, or directly after such a data transmission concludes, it is thus necessary merely to authenticate the data store when the power has returned. In accordance with one advantageous development of the invention, a power failure during a read operation from the data store expediently has the effect that the functional modules remain in the present state until the power returns and then continue the read operation from this state after identification data have first of all been compared with one another, preferably reciprocally. Unless express mention has been made, the functional features always relate to a form of the arrangement according to which the claimed function can be performed using the inventive arrangement. Besides the inventive arrangement, the subject matter of the invention is also an inventive method for operating an arrangement as claimed in at least one or a combination of the claims. In this context, particularly the claimed features of the invention are the subject matter of an inventive method even in the absence of an express appropriate back reference. The invention is described in more detail below with reference to a specific exemplary embodiment without any restrictive action for the purposes of clarification. In the drawing: Figure 1 shows a schematic illustration of an arrangement based on the invention, Figure 2 shows a schematic illustration of the flow of the fundamental processes during operation of an arrangement based on the invention, Figure 3 shows a schematic illustration of the implementation of a ring memory from a virtual depiction based on the invention, Figure 4 shows a schematic illustration of the cooperation of logic functional modules with the memory, coordinated by means of a status variable based on the invention. Figure 1 shows an arrangement 1 based on the invention having a tachograph DTCO which is connected to a sensor S providing a speed signal n and has data card holders 3 into which data cards 4, 5 can be inserted. The tachograph DTCO has various logic functional modules FM which comprise, inter alia, a central processing unit CPU, an interface management module IF, an encryption module KRY, a memory MEM and a printer controller PRN. In addition, the tachograph DTCO also has a display unit 6, various operator control elements 7, a power supply U and a print module 8. The individual functional modules FM are connected to one another so as to transmit signals. The data cards 4, 5 respectively have an interface 11, 12 which can connect to an interface (not shown in more detail) of the tachograph DTCO for the purpose of data transmission. The data cards 4, 5 can use this interface 11, 12 to transmit respective information stored in a data store 13, 14 on the data card 4, 5 to the tachograph 2, with encryption modules KRY both in the data cards 4, 5 and in the tachograph DTCO ensuring cryptologically protected transmission. Figure 2 shows the schematic flow of the production of a virtual map VI in a memory DMEM of the tachograph DTCO on the basis of the data store 13 on the data card 4. In Figure 2, the reference symbols for the elements which correspond to those of the actual data store 13 have been provided with a small dash. In a first step (1), the tachograph DTCO and the data store 13 on the data card 4 connect to one another for the purpose of signal transmission, and an authentication operation (Auth.) is automatically initiated between these two participants in the communication. Following successful authentication (Auth.), the tachograph DTCO creates a virtual map VI in its memory DMEM from the data store 13 on the data card 4. This involves the total structure of the data store being mapped in the virtual map VI. This comprises a first memory portion 16, 16' of the usual nature and a second memory portion 17, 17', which is in the form of a ring memory RNG, RNG' . Following production of the virtual map VI in the memory DMEM of the tachograph DTCO, the recording mode of the tachograph 2 essentially takes place in step (3), during which the speed signal n is recorded in the virtual map VI. Every 12 hours, the virtual map VI is aligned (not shown) with the data store 13 on the data card 4. This alignment essentially involves the entries in the ring memory RNG being aligned with one another. In the event of a removal request (EJECT) on the digital tachograph DTCO, as shown in step (4) , the virtual map VI is first of all aligned with the data store 13 and then the data card 4 is ejected. Figure 3 shows the alignment of the virtual map VI, particularly the ring memory RNG', with the data store 13 or its ring memory RNG. A crucial factor in this context is the structure of the ring memory RNG in the virtual map VI, which has an actually linear structure, with a prescribed addressing order SEQADR allowing addressing of the last memory location Xst in this linear memory to be followed by the addressing of a first memory location 1st. In the ring memory RNG of the data card, this corresponds to the memory locations lstrng and Xstrng. The ring memory RNG' of the tachograph DTCO or of the memory DMEM has change pointers p1, p2 which are used to mark the changes which have been made following the last alignment of the virtual map with the data store 13. In this context, the start of the changed entry is registered using the pointer denoted by p1, the situation shown in figure 3 showing an entry which is denoted by d head and act., which extends via the end address Xst and the start address 1st of the virtual map VI, and besides the first change pointer p1, a second change pointer p2 also marks the location at which the write operation was continued after the end address Xst, namely at the start address 1st. The entry comprises a header and the stored types of operation by the vehicle driver act.. The change pointers p1, p2 respectively also have appended information in nl, n2 about the number of bytes which have been stored since the last alignment in the ring memory starting from the indicated location. Accordingly, the respective start point for the data to be aligned and the length are indicated by means of the change pointer. Figure 4 schematically shows the coordination of the functional modules FM when writing to the virtual map VI using a card data status CDS. Various functional modules FM, for example the central processing unit CPU, an active hardware protection element AH, an interface manager IF, a print module PRN or a sensor Sen, write to the memory DMEM or its virtual map VI largely autonomously. So that no conflicts arise in this context, a central status variable CDS is provided which is assigned a value reciprocally by the functional modules FM and a map status module CDSA. In this case, the map status module CDSA assigns the status variable CDS a respective value which is associated with a functional module FM. The functional modules FM regularly request the value of the status variable CDS and initiate queuing write operations on the map VI if the value corresponds to the value which is associated with the relevant functional module. Following conclusion of the write operation, the functional module assigns the status variable CDS a new value which indicates conclusion of the write operation to the map status module, so that the status variable CDS can be assigned a new value. WE CLAIM 1. A system (1) having a tachograph (DTCO) and having a data store (13, 14), particularly a data store (13, 14) on a data card (4, 5), where the tachograph (DTCO) has an interface which is used for data interchange between the tachograph (DTCO) and the data store (13, 14), which tachograph (DTCO) has logic functional modules (FM) and at least one memory (DMEM) and the logic functional modules (FM) are in a form such that at the start of the data transmission a virtual map (VI) of the data store (13, 14) is first of all created in the memory (DMEM) of the tachograph (DTCO), subsequent read and write access operations by the logic functional modules (FM) are first of all effected on the virtual map (VI) in the memory (DMEM), and a write operation is regularly effected by accessing the data store (13,14) on the data card (4, 5), during which the differences between the virtual map (VI) and the data store (13, 14) are aligned, characterized in that the regular read and write access is effected at periodic intervals of time and/or when a particular volume of data needs to be aligned between the virtual map (VI) and the data store (13,14) on the basis of changes in the map. 2. The system (1) as claimed in claim 1, wherein the regular read and write access is effected every 12 hours. 3. The system (1) as claimed in claim 1, wherein before the data store (13, 14) is separated from the tachograph (DTCO) the virtual map (VI) is aligned with the data store (13,14). 4. The system (1) as claimed in claim 1, wherein the data transmission between the data store (13, 14) and the tachograph (DTCO) takes place in encrypted form. 5. The system (1) as claimed in claim 1, wherein the data store (13,14) has a ring memory (RNG). 6. The system (1) as claimed in claim 5, wherein the map (VI) of the ring memory (RNG1) is in the form of a linear memory (DMEM), with a start address (1st) for the first entry and an end address (xst) for the last entry, where a stipulated addressing order (ADRSEQ) provides for the call to the end address (xst) to be followed by the call to the start address (1st). 7. The system (1) as claimed in claim 1, wherein the virtual map (VI) of the data store (13, 14) maps the architecture of the data store (13, 14), and the data stored in the ring memory (RNG) are mapped in the map (VI) only in part. 8. The system (1) as claimed in one of claims 5-7, wherein the virtual map (VI), following initial production, first of all maps only the data from the last entry block in the ring memory (RNG) of the data store (13,14). 9. The system (1) as claimed in one of claims 5-7, wherein the virtual map (VI) has at least one associated change pointer (p1, p2), namely the data store (13,14) of the tachograph (DTCO) stores the location of the virtual map (VI) of the ring memory (RNG) at which the first change since the last alignment was made. 10. The system (1) as claimed in claim 9, wherein a write operation in the virtual map (VI) extending from the end address (xst) to the start address (1st) of the map (VI) involves at least one first change pointer (p1) marking the location in front of the end address (xst) at which the changes after the last alignment have started and at least one second change pointer (p2) marks the location at which the write operation was continued after the end address (xst). 11. The system (1) as claimed in claim 9 or 10, wherein the change pointers (pi) additionally also comprise information about the number (n1, n2) of bytes which have been stored in the ring memory (RNG') starting from the indicated location since the last alignment. 12. The system (1) as claimed in one of the preceding claims, wherein single instances of the logic functional module (FM) effect read or write access operations on the map (VI) and in this context are coordinated by means of a central status variable (CDS). 13. The system (1) as claimed in one of the preceding claims, wherein single instances of the logic functional modules (FM) effect write access operations on memory areas of the map (VI) and in this context are coordinated by means of a central status variable, the functional modules (FM) regularly requesting the status variable (CDS) and, when the status variable (CDS) has a particular value which is associated with the respective requesting functional module (FM), initiating queuing write operations. 14. The system (1) as claimed in the preceding claim, wherein the logic functional modules (FM) which effect the write access operations on a memory area of the map (VI) change the status variable (CDS) following the conclusion of the queuing write access operations. 15. The system (1) as claimed in the preceding claim, wherein the logic functional modules (FM) comprise a map status module (CDSA) which regularly retrieves the status variable (CDS) and allocates it a new value if another functional module (FM) has previously changed the value, which new value is associated with a particular functional module (FM) for the purpose of allocating the write access. 16. The system (1) as claimed in one of the preceding claims, wherein the arrangement (1) comprises an electrical power supply (U) and is in a form such that, when the latter has failed, any other access to the data store (13, 14) is first of all preceded by identification data from the data store (13, 14) being compared with those from the virtual map of the data store (13,14). 17. The system (1) as claimed in the preceding claim, wherein it is in a form such that, in the event of a power failure, directly before entering a read or write operation from or to the data store (13,14), when the power has returned, it first of all compares identification data from the data store (13, 14) with those from the virtual map of the data store (13, 14) and then starts the read or write operation. 18. The system (1) as claimed in the preceding claim, wherein in the event of a power failure during a read operation from the data store (13, 14) the functional modules (FM) remain in the present state until the power returns and then continue the read operation from this state after identification data from the data store (13, 14) have first of all been compared with those from the virtual map (VI) of the data store (13,14). 19. The system (1) as claimed in one of the preceding claims, wherein in the event of a power failure directly following the conclusion of a read or write operation from or to the data store (13, 14), when the power has returned, identification data from the data store (13, 14) are first of all compared with those from the virtual map of the data store (13,14). 20. A method for operating a system (1) as claimed in one of the preceding claims. ABSTRACT TITLE : "A SYSTEM WITH A TACHOGRAPH AND A DATA STORE FOR DATA INTERCHANGE BETWEEN THE TACHOGRAPH AND THE DATA STORE" A system (1) having a tachograph (DTCO) and having a data store (13, 14), particularly a data store (13, 14) on a data card (4, 5), where the tachograph (DTCO) has an interface which is used for data interchange between the tachograph (DTCO) and the data store (13, 14), which tachograph (DTCO) has logic functional modules (FM) and at least one memory (DMEM) and the logic functional modules (FM) are in a form such that at the start of the data transmission a virtual map (VI) of the data store (13, 14) is first of all created in the memory (DMEM) of the tachograph (DTCO), subsequent read and write access operations by the logic functional modules (FM) are first of all effected on the virtual map (VI) in the memory (DMEM), and a write operation is regularly effected by accessing the data store (13, 14) on the data card (4, 5), during which the differences between the virtual map (VI) and the data store (13, 14) are aligned, characterized in that the regular read and write access is effected at periodic intervals of time and/or when a particular volume of data needs to be aligned between the virtual map (VI) and the data store (13, 14) on the basis of changes in the map.

Full Text

FIELD OF THE INVENTION
The invention relates to an arrangement having a tachograph and having a data
store, particularly a data store on a data card, where the tachograph has an
interface which is used for data interchange between the tachograph and the
data store, which tachograph has logic functional modules and at least one
memory.
BACKGROUND OF THE INVENTION
In line with EC regulation No 3821/85, in future the tachographs used in
commercial vehicles to record operating data will no longer, as conventionally,
use analogue means to write on a paper tachograph disk but rather will store the
speed over time digitally in a data store, namely a data store on a data card. The
EC regulation contains extensive details as to how the data to be recorded,
which need to meet the requirements for legal evidence, inter alia, are to be
stored and to be protected against manipulation. To meet the stringent
requirements of the regulation, very complex cryptological protection
mechanisms and authentication processes need to be implemented. Particular
focus in this context is on allowing the transmission of data between the data
store on the data card and the tachograph. A data card holding apparatus is
already the subject matter of German laid-open specification DE 103 21 252 Al,
which describes an antimanipulation holder for a card in a tachograph as
described above. Particularly the transmission of data between the data store on
the data card and a memory in the tachograph needs to be protected against
manipulation, since experience shows that such attacks are to be feared in this
area. For this reason, pertinent tachographs and data cards respectively provide
an encryption unit as an integral component

which is used to transmit data in cryptologically protected form exclusively using
a session key. This protection is extremely complex, however, and requires a lot
of patience from the user, since access times are extended almost intolerably on
account of the protection of the data transmission between the tachograph and
the data card. In line with ISO 7816, the read/write access to the data store on
the data card is furthermore limited to a length of 256 bytes, which means that
the communication via the serial connection used at this location takes place
very slowly on the basis of the EC regulation.
DE 195 33 515 Al discloses a tachograph arrangement. A driver's card has a
nonvolatile overrideable memory for storing control data. The tachograph
arrangement has a device for writing control data to the memory on the driver's
card and for reading the control data stored in said memory. A temporary control
data store and a control device are provided. The control device controls the
operation of the tachograph arrangement such that when the driver' s card is
inserted into the tachograph the control data stored in the driver's card are
loaded into the temporary control data store, are updated in the temporary
control data store while the driver's card remains in the tachograph, and the
updated control data are loaded into the control data store of the driver's card
when said driver's card is removed. Control data are secondary data which are
obtained by further processing of primary data relating to the operation of
driving, particularly by means of addition over time. The secondary data contain
relevant information about the working time regime.
GB 2 271 180 A discloses an electronic tachograph with a vehicle position-finding
unit. The tachograph has a central processing unit and a memory to

which the processing unit has direct access. The processing unit also uses information
from a removable memory card which is associated with the driver or co-driver. The
memory card sends information such as the identity of the driver and driver parameters.
The information received from the memory card is held in the tachograph's memory.
The memory also contains outputs from the processing unit which are supplied to the
memory card.
OBJECT OF THE INVENTION
Against the background of the prior art, it is an object of the invention to shorten access
times when dealing with the tachograph without losses of security, or particularly in
respect of the communication between the tachographs and the data card.
SUMMARY OF THE INVENTION
To achieve the object, it is proposed that the logic functional modules be in a form such
that at the start of the data transmission a virtual map of the data store is first of all
created in the memory of the tachograph, subsequent read and write access operations
by the logic functional modules are first of all effected on the virtual map in the
memory, and a write operation is regularly effected by accessing the data store on the
data card, during which the differences between the virtual map and the data store are
aligned. In this context, the regular read and write access is effected at periodic
intervals of time and/or when a particular volume of data needs to be aligned between
the virtual map and the data store on the basis of changes in the map.
One particular advantage of the invention is the saving of a large number of data
transmission cycles between the tachograph and the data store or the data card. Since
pertinent tachographs regularly have two holding apparatuses for two data cards, the
saving of this complexity has almost

double the effect. Since the regularly interrupt-controlled recording signals from
the speed sensor, which queue up at a high frequency, mean that the
tachograph's processing unit utilizes the central processing unit

to a relatively high degree during operation, the load relief
based on the invention is a great advantage. Regular alignment
can take place comparatively rarely, for example at intervals
of 12 hours in each case. In the event of a request to remove
the data card from the tachograph or when the data store is
separated from the tachograph, alignment is necessary between
the virtual map in the memory and the data store on the data
card. The request for removal is regularly made when the
commercial vehicle is at a standstill, however, which means
that the high-frequncy speed signal is not queuing and the
central processing unit is relieved of load anyway. This allows
acceptable access times to be implemented despite the necessary
alignment when the data store is separated from the tachograph.
As an alternative or in addition to regular read and write
access to the data store, particularly the data card, by the
tachograph at periodic intervals of time, preferably every 12
hours, such data interchange can also take place when a
particular volume of data needs to be aligned between the
virtual map and the data store on the basis of changes in the
map. A minimum standard which would nevertheless satisfy
pertinent security provisions is the option of aligning the
virtual map with the data store before the data store is
separated from the tachograph. Advantageously, the tachograph
is in a form such that the data card is held completely by the
tachograph's data card holding apparatus and cannot be removed
from the appliance directly, but rather the user communicates a
removal request to the appliance by pushing a button, whereupon
the data card is ejected from the tachograph following an
appropriate interchange of data. Although a modern tachograph
is regularly already provided with all the security mechanisms
possible from a mechanical point of view which protect the data
transmission between the data store and the tachograph against

manipulation, the data transmission between the data store and
the tachograph regularly takes place in encrypted form. The
data store is used to record particularly the speed data from
the commercial vehicle and the activities of the vehicle
driver. In this regard, the available storage space on the data
card is relatively limited, which means that a portion of the
data store is expediently in the form of a ring memory and in
this way the oldest recordings are always overwritten with the
most recent. Taking this into account, the map of the ring
memory may advantageously be in the form of a linear memory,
with a start address for the first entry and an end address for
the last entry, where a stipulated addressing order provides
for the call to the end address to be followed by the call to
the start address. In this context, it is expedient if,
although the virtual map of the data store maps the
architecture of the data store, the data stored in the ring
memory are mapped in the map only in part. Full transmission of
the entire content of the data store, for example when the card
is inserted into the tachograph, sometimes takes an
unacceptably long time, the old data not necessarily having any
corresponding practical benefit in this context. It therefore
makes sense if the virtual map, following initial production,
first of all maps only the data from the last entry block in
the ring memory of the data store.
To avoid excess complexity for the data transmission, it makes
sense if the virtual map has at least one associated change
pointer, namely the data store of the tachograph stores the
location of the virtual map of the ring memory at which the
first change since the last alignment was made.
In one advantageous development of the invention, a write
operation in the virtual map extending from the end address to
the start address of the map involves at least

one change pointer marking the location in front of the end
address at which the changes after the last alignment have
started and at least one second change pointer marks the
location at which the write operation was continued after the
end address. Such marking over the address jump in the ring
memory ensures conflictless alignment between the data store
and the memory of the tachograph. The reliability of this
operation can be additionally increased if the change pointers
additionally also comprise information about the number of
bytes which have been stored in the ring memory starting from
the indicated location since the last alignment.
A lot of time may be lost when various logic functional modules
effect read or write access to the map and fixed time windows
have been prescribed for this. Although such operations may
also be carried out under interrupt control, this destabilizes
operations in the central processing unit. It is therefore
particularly expedient to coordinate the logic functional
modules effecting read or write access to the map using a
central status variable. In this context, it makes sense if the
functional modules regularly request the status variable and,
when the status variable has a particular value which is
associated with the respective requesting functional module,
initiate queuing write operations. As a ready message, so to
speak, provision may be made for the logic functional modules
which carry out the write access operations on the memory area
of the map to change the status variable following the
conclusion of the queuing tasks. Conflictless coordination of
these access operations on the data store is assured
particularly if the logic functional modules comprise a map
status module which regularly retrieves the status variable and
allocates it a new value if another functional module has
previously changed the value, which new value is associated
with a particular functional module for the purpose of
allocating the write access.

The invention provides particular runtime advantages if the
functional modules comprise an encryption unit which is used to
encrypt elements of the data transmission between the
tachograph and the data store. To this end, the data store may
likewise have an encryption unit.
On the basis of the special inventive marking of the data from
the virtual map which are to be aligned, the invention provides
further advantages when the electrical power supply fails. In
this case, the arrangement may provide that when the power
supply has failed, any other access to the data store is first
of all preceded by identification data from the data store
being compared with those from the virtual map of the data
store. This configuration makes sense because, when the supply
voltage is cut off, an attempt at manipulation may possibly
provide for the data store to be replaced. The advantage of the
invention at this junction is particularly that the virtual map
of the data store, including the identification data, is
already available and hence merely a comparison is necessary.
If a power failure occurs directly before a data transmission
commences, or directly after such a data transmission
concludes, it is thus necessary merely to authenticate the data
store when the power has returned. In accordance with one
advantageous development of the invention, a power failure
during a read operation from the data store expediently has the
effect that the functional modules remain in the present state
until the power returns and then continue the read operation
from this state after identification data have first of all
been compared with one another, preferably reciprocally.
Unless express mention has been made, the functional features
always relate to a form of the arrangement according to which
the claimed function can be performed

using the inventive arrangement. Besides the inventive
arrangement, the subject matter of the invention is also an
inventive method for operating an arrangement as claimed in at
least one or a combination of the claims. In this context,
particularly the claimed features of the invention are the
subject matter of an inventive method even in the absence of an
express appropriate back reference.
The invention is described in more detail below with reference
to a specific exemplary embodiment without any restrictive
action for the purposes of clarification. In the drawing:
Figure 1 shows a schematic illustration of an arrangement
based on the invention,
Figure 2 shows a schematic illustration of the flow of the
fundamental processes during operation of an
arrangement based on the invention,
Figure 3 shows a schematic illustration of the implementation
of a ring memory from a virtual depiction based on
the invention,
Figure 4 shows a schematic illustration of the cooperation of
logic functional modules with the memory, coordinated
by means of a status variable based on the invention.
Figure 1 shows an arrangement 1 based on the invention having a
tachograph DTCO which is connected to a sensor S providing a
speed signal n and has data card holders 3 into which data
cards 4, 5 can be inserted. The tachograph DTCO has various
logic functional modules FM which comprise, inter alia, a
central processing unit CPU, an interface management module IF,
an encryption module KRY, a memory MEM and a printer controller
PRN. In addition, the tachograph DTCO also has a display unit
6, various operator control elements 7, a power supply U and a
print module 8. The individual

functional modules FM are connected to one another so as to
transmit signals. The data cards 4, 5 respectively have an
interface 11, 12 which can connect to an interface (not shown
in more detail) of the tachograph DTCO for the purpose of data
transmission. The data cards 4, 5 can use this interface 11, 12
to transmit respective information stored in a data store 13,
14 on the data card 4, 5 to the tachograph 2, with encryption
modules KRY both in the data cards 4, 5 and in the tachograph
DTCO ensuring cryptologically protected transmission.
Figure 2 shows the schematic flow of the production of a
virtual map VI in a memory DMEM of the tachograph DTCO on the
basis of the data store 13 on the data card 4. In Figure 2, the
reference symbols for the elements which correspond to those of
the actual data store 13 have been provided with a small dash.
In a first step (1), the tachograph DTCO and the data store 13
on the data card 4 connect to one another for the purpose of
signal transmission, and an authentication operation (Auth.) is
automatically initiated between these two participants in the
communication. Following successful authentication (Auth.), the
tachograph DTCO creates a virtual map VI in its memory DMEM
from the data store 13 on the data card 4. This involves the
total structure of the data store being mapped in the virtual
map VI. This comprises a first memory portion 16, 16' of the
usual nature and a second memory portion 17, 17', which is in
the form of a ring memory RNG, RNG' . Following production of
the virtual map VI in the memory DMEM of the tachograph DTCO,
the recording mode of the tachograph 2 essentially takes place
in step (3), during which the speed signal n is recorded in the
virtual map VI. Every 12 hours, the virtual map VI is aligned
(not shown) with the data store 13 on the data card 4. This
alignment essentially involves the entries in the ring memory
RNG

being aligned with one another. In the event of a removal
request (EJECT) on the digital tachograph DTCO, as shown in
step (4) , the virtual map VI is first of all aligned with the
data store 13 and then the data card 4 is ejected.
Figure 3 shows the alignment of the virtual map VI,
particularly the ring memory RNG', with the data store 13 or
its ring memory RNG. A crucial factor in this context is the
structure of the ring memory RNG in the virtual map VI, which
has an actually linear structure, with a prescribed addressing
order SEQADR allowing addressing of the last memory location
Xst in this linear memory to be followed by the addressing of a
first memory location 1st. In the ring memory RNG of the data
card, this corresponds to the memory locations lstrng and
Xstrng.
The ring memory RNG' of the tachograph DTCO or of the memory
DMEM has change pointers p1, p2 which are used to mark the
changes which have been made following the last alignment of
the virtual map with the data store 13. In this context, the
start of the changed entry is registered using the pointer
denoted by p1, the situation shown in figure 3 showing an entry
which is denoted by d head and act., which extends via the end
address Xst and the start address 1st of the virtual map VI,
and besides the first change pointer p1, a second change
pointer p2 also marks the location at which the write operation
was continued after the end address Xst, namely at the start
address 1st. The entry comprises a header and the stored types
of operation by the vehicle driver act.. The change pointers
p1, p2 respectively also have appended information in nl, n2
about the number of bytes which have been stored since the last
alignment in the ring memory starting from the indicated
location. Accordingly, the respective start point for the

data to be aligned and the length are indicated by means of the
change pointer.
Figure 4 schematically shows the coordination of the functional
modules FM when writing to the virtual map VI using a card data
status CDS. Various functional modules FM, for example the
central processing unit CPU, an active hardware protection
element AH, an interface manager IF, a print module PRN or a
sensor Sen, write to the memory DMEM or its virtual map VI
largely autonomously. So that no conflicts arise in this
context, a central status variable CDS is provided which is
assigned a value reciprocally by the functional modules FM and
a map status module CDSA. In this case, the map status module
CDSA assigns the status variable CDS a respective value which
is associated with a functional module FM. The functional
modules FM regularly request the value of the status variable
CDS and initiate queuing write operations on the map VI if the
value corresponds to the value which is associated with the
relevant functional module. Following conclusion of the write
operation, the functional module assigns the status variable
CDS a new value which indicates conclusion of the write
operation to the map status module, so that the status variable
CDS can be assigned a new value.

WE CLAIM
1. A system (1) having a tachograph (DTCO) and having a data store (13,
14), particularly a data store (13, 14) on a data card (4, 5), where the
tachograph (DTCO) has an interface which is used for data interchange
between the tachograph (DTCO) and the data store (13, 14), which
tachograph (DTCO) has logic functional modules (FM) and at least one
memory (DMEM) and the logic functional modules (FM) are in a form
such that at the start of the data transmission a virtual map (VI) of the
data store (13, 14) is first of all created in the memory (DMEM) of the
tachograph (DTCO), subsequent read and write access operations by the
logic functional modules (FM) are first of all effected on the virtual map
(VI) in the memory (DMEM), and a write operation is regularly effected
by accessing the data store (13,14) on the data card (4, 5), during which
the differences between the virtual map (VI) and the data store (13, 14)
are aligned, characterized in that the regular read and write access is
effected at periodic intervals of time and/or when a particular volume
of data needs to be aligned between the virtual map (VI) and the data
store (13,14) on the basis of changes in the map.
2. The system (1) as claimed in claim 1, wherein the regular read and write
access is effected every 12 hours.
3. The system (1) as claimed in claim 1, wherein before the data store (13,
14) is separated from the tachograph (DTCO) the virtual map (VI) is
aligned with the data store (13,14).

4. The system (1) as claimed in claim 1, wherein the data transmission
between the data store (13, 14) and the tachograph (DTCO) takes place
in encrypted form.
5. The system (1) as claimed in claim 1, wherein the data store (13,14) has
a ring memory (RNG).
6. The system (1) as claimed in claim 5, wherein the map (VI) of the ring
memory (RNG1) is in the form of a linear memory (DMEM), with a start
address (1st) for the first entry and an end address (xst) for the last
entry, where a stipulated addressing order (ADRSEQ) provides for the call
to the end address (xst) to be followed by the call to the start address
(1st).
7. The system (1) as claimed in claim 1, wherein the virtual map (VI) of the
data store (13, 14) maps the architecture of the data store (13, 14), and
the data stored in the ring memory (RNG) are mapped in the map (VI)
only in part.
8. The system (1) as claimed in one of claims 5-7, wherein the virtual map
(VI), following initial production, first of all maps only the data from the
last entry block in the ring memory (RNG) of the data store (13,14).
9. The system (1) as claimed in one of claims 5-7, wherein the virtual map
(VI) has at least one associated change pointer (p1, p2), namely the data
store (13,14) of the tachograph (DTCO) stores the location of the virtual

map (VI) of the ring memory (RNG) at which the first change since the
last alignment was made.
10. The system (1) as claimed in claim 9, wherein a write operation in the
virtual map (VI) extending from the end address (xst) to the start
address (1st) of the map (VI) involves at least one first change pointer
(p1) marking the location in front of the end address (xst) at which the
changes after the last alignment have started and at least one second
change pointer (p2) marks the location at which the write operation was
continued after the end address (xst).
11. The system (1) as claimed in claim 9 or 10, wherein the change pointers
(pi) additionally also comprise information about the number (n1, n2) of
bytes which have been stored in the ring memory (RNG') starting from
the indicated location since the last alignment.
12. The system (1) as claimed in one of the preceding claims, wherein single
instances of the logic functional module (FM) effect read or write access
operations on the map (VI) and in this context are coordinated by means
of a central status variable (CDS).
13. The system (1) as claimed in one of the preceding claims, wherein single
instances of the logic functional modules (FM) effect write access
operations on memory areas of the map (VI) and in this context are
coordinated by means of a central status variable, the functional modules
(FM) regularly requesting the status variable (CDS) and, when the status

variable (CDS) has a particular value which is associated with the
respective requesting functional module (FM), initiating queuing write
operations.
14. The system (1) as claimed in the preceding claim, wherein the logic
functional modules (FM) which effect the write access operations on a
memory area of the map (VI) change the status variable (CDS) following
the conclusion of the queuing write access operations.
15. The system (1) as claimed in the preceding claim, wherein the logic
functional modules (FM) comprise a map status module (CDSA) which
regularly retrieves the status variable (CDS) and allocates it a new value
if another functional module (FM) has previously changed the value,
which new value is associated with a particular functional module (FM)
for the purpose of allocating the write access.
16. The system (1) as claimed in one of the preceding claims, wherein the
arrangement (1) comprises an electrical power supply (U) and is in a
form such that, when the latter has failed, any other access to the data
store (13, 14) is first of all preceded by identification data from the data
store (13, 14) being compared with those from the virtual map of the
data store (13,14).
17. The system (1) as claimed in the preceding claim, wherein it is in a form
such that, in the event of a power failure, directly before entering a read
or write operation from or to the data store (13,14), when the power has
returned, it first of all compares identification data from the

data store (13, 14) with those from the virtual map of the data store (13,
14) and then starts the read or write operation.
18. The system (1) as claimed in the preceding claim, wherein in the event of
a power failure during a read operation from the data store (13, 14) the
functional modules (FM) remain in the present state until the power
returns and then continue the read operation from this state after
identification data from the data store (13, 14) have first of all been
compared with those from the virtual map (VI) of the data store (13,14).
19. The system (1) as claimed in one of the preceding claims, wherein in the
event of a power failure directly following the conclusion of a read or
write operation from or to the data store (13, 14), when the power has
returned, identification data from the data store (13, 14) are first of all
compared with those from the virtual map of the data store (13,14).
20. A method for operating a system (1) as claimed in one of the preceding
claims.

ABSTRACT

TITLE : "A SYSTEM WITH A TACHOGRAPH AND A DATA STORE FOR
DATA INTERCHANGE BETWEEN THE TACHOGRAPH AND THE DATA
STORE"
A system (1) having a tachograph (DTCO) and having a data store (13, 14),
particularly a data store (13, 14) on a data card (4, 5), where the tachograph
(DTCO) has an interface which is used for data interchange between the
tachograph (DTCO) and the data store (13, 14), which tachograph (DTCO) has
logic functional modules (FM) and at least one memory (DMEM) and the logic
functional modules (FM) are in a form such that at the start of the data
transmission a virtual map (VI) of the data store (13, 14) is first of all created in
the memory (DMEM) of the tachograph (DTCO), subsequent read and write
access operations by the logic functional modules (FM) are first of all effected on
the virtual map (VI) in the memory (DMEM), and a write operation is regularly
effected by accessing the data store (13, 14) on the data card (4, 5), during
which the differences between the virtual map (VI) and the data store (13, 14)
are aligned, characterized in that the regular read and write access is effected at
periodic intervals of time and/or when a particular volume of data needs to be
aligned between the virtual map (VI) and the data store (13, 14) on the basis of
changes in the map.

A SYSTEM WITH A TACHOGRAPH AND A DATA STORE FOR DATA INTERCHANGE BETWEEN THE TACHOGRAPH AND THE DATA STORE

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