Commission Implementing Regulation (EU) 2016/799Show full title

2.2. Data download protocol U.K.

The protocol is structured on a master-slave basis, with the IDE playing the master role and the VU playing the slave role.

The message structure, types and flow are principally based on the Keyword Protocol 2000 (KWP) (ISO 14230-2 Road vehicles — Diagnostic systems — Keyword protocol 2000 — Part2: Data link layer).

The application layer is principally based on the current draft to date of ISO 14229-1 (Road vehicles — Diagnostic systems — Part 1: Diagnostic services, version 6 of 22 February 2001).

2.2.1 Message structure U.K.

DDP_002 All the messages exchanged between the IDE and the VU are formatted with a structure consisting of three parts: U.K.

• Header composed by a Format byte (FMT), a Target byte (TGT), a Source byte (SRC) and possibly a Length byte (LEN),

• Data field composed by a Service Identifier byte (SID) and a variable number of data bytes, which can include an optional diagnostic session byte (DS_) or an optional transfer parameter byte (TRTP or TREP).

• Checksum composed by a Checksum byte (CS).

Header				Data field					Checksum
FMT	TGT	SRC	LEN	SID	DATA	…	…	…	CS
4 bytes				Max 255 bytes					1 byte

The TGT and SRC byte represent the physical address of the recipient and originator of the message. Values are F0 Hex for the IDE and EE Hex for the VU.

The LEN byte is the length of the Data field part.

The Checksum byte is the 8 bit sum series modulo 256 of all the bytes of the message excluding the CS itself.

FMT, SID, DS_, TRTP and TREP bytes are defined later in this document.

DDP_003 In the case where the data to be carried by the message is longer than the space available in the data field part, the message is actually sent in several sub messages. Each sub message bears a header, the same SID, TREP and a 2-byte sub message counter indicating the sub message number within the total message. To enable error checking and abort the IDE acknowledges every sub message. The IDE can accept the sub message, ask for it to be re-transmitted, request the VU to start again or abort the transmission. U.K.

DDP_004 If the last sub message contains exactly 255 bytes in the data field, a final sub message with an empty (except SID TREP and sub message counter) data field must be appended to show the end of the message. U.K.

Example:

Header	SID	TREP	Message	CS
4 Bytes	Longer than 255 Bytes

Will be transmitted as:

Header	SID	TREP	00	01	Sub message 1	CS
4 Bytes	255 Bytes

Header	SID	TREP	00	02	Sub message 2	CS
4 Bytes	255 Bytes

…

Header	SID	TREP	xx	yy	Sub message n	CS
4 Bytes	Less than 255 Bytes

or as:

Header	SID	TREP	00	01	Sub message 1	CS
4 Bytes	255 Bytes

Header	SID	TREP	00	02	Sub message 2	CS
4 Bytes	255 Bytes

…

Header	SID	TREP	xx	yy	Sub message n	CS
4 Bytes	255 Bytes

Header	SID	TREP	xx	yy + 1	CS
4 Bytes	4 bytes

2.2.2 Message types U.K.

The communication protocol for data download between the VU and the IDE requires the exchange of 8 different message types.

The following table summarises these messages.

[F1 Message Structure		Max 4 Bytes Header				Max 255 Bytes Data			1 Byte CheckSum
IDE ->	<- VU	FMT	TGT	SRC	LEN	SID	DS_ / TRTP	DATA	CS
Start Communication Request		81	EE	F0		81			E0
Positive Response Start Communication		80	F0	EE	03	C1		EA, 8F	9B
Start Diagnostic Session Request		80	EE	F0	02	10	81		F1
Positive Response Start Diagnostic		80	F0	EE	02	50	81		31
Link Control Service
Verify Baud Rate (stage 1)
9 600 Bd		80	EE	F0	04	87		01,01,01	EC
19 200 Bd		80	EE	F0	04	87		01,01,02	ED
38 400 Bd		80	EE	F0	04	87		01,01,03	EE
57 600 Bd		80	EE	F0	04	87		01,01,04	EF
115 200 Bd		80	EE	F0	04	87		01,01,05	F0
Positive Response Verify Baud Rate		80	F0	EE	02	C7		01	28
Transition Baud Rate (stage 2)		80	EE	F0	03	87		02,03	ED
Request Upload		80	EE	F0	0A	35		00,00,00,00,00,FF,FF, FF,FF	99
Positive Response Request Upload		80	F0	EE	03	75		00,FF	D5
Transfer Data Request
Overview		80	EE	F0	02	36	01 or 21		97
Activities		80	EE	F0	06	36	02 or 22	Date	CS
Events & Faults		80	EE	F0	02	36	03 or 23	Date	99
Detailed Speed		80	EE	F0	02	36	04 or 24	Date	9 A
Technical Data		80	EE	F0	02	36	05 or 25	Date	9B
Card download		80	EE	F0	02	36	06	Slot	CS
Positive Response Transfer Data		80	F0	EE	Len	76	TREP	Data	CS
Request Transfer Exit		80	EE	F0	01	37			96
Positive Response Request Transfer Exit		80	F0	EE	01	77			D6
Stop Communication Request		80	EE	F0	01	82			E1
Positive Response Stop Communication		80	F0	EE	01	C2			21
Acknowledge sub message		80	EE	F0	Len	83		Data	CS
Negative responses
General reject		80	F0	EE	03	7F	Sid Req	10	CS
Service not supported		80	F0	EE	03	7F	Sid Req	11	CS
Sub function not supported		80	F0	EE	03	7F	Sid Req	12	CS
Incorrect Message Length		80	F0	EE	03	7F	Sid Req	13	CS
Conditions not correct or Request sequence error		80	F0	EE	03	7F	Sid Req	22	CS
Request out of range		80	F0	EE	03	7F	Sid Req	31	CS
Upload not accepted		80	F0	EE	03	7F	Sid Req	50	CS
Response pending		80	F0	EE	03	7F	Sid Req	78	CS
Data not available		80	F0	EE	03	7F	Sid Req	FA	CS]

Textual Amendments

F1 Substituted by Commission Implementing Regulation (EU) 2018/502 of 28 February 2018 amending Implementing Regulation (EU) 2016/799 laying down the requirements for the construction, testing, installation, operation and repair of tachographs and their components (Text with EEA relevance).

Notes: U.K.

• [F2 TRTP 21 to 25 are used for Generation 2 type of VU data download requests, TRTP 01 to 05 are used for Generation 1 type of VU data download requests, which can only be accepted by the VU in the frame of drivers' control performed by a non EU control authority, using a first generation control card.

• TRTP 11 to 19 and 31 to 39 are reserved for manufacturer specific download requests.]

• Sid Req = the Sid of the corresponding request.

• TREP = the TRTP of the corresponding request.

• Dark cells denote that nothing is transmitted.

• The term upload (as seen from the IDE) is used for compatibility with ISO 14229. It means the same as download (as seen from the VU).

• Potential 2-byte sub message counters are not shown in this table.

• Slot is the slot number, either “1” (card on driver slot) or “2” (card on co-driver slot)

• In case the slot is not specified, the VU shall select slot 1 if a card is inserted in this slot and it shall select slot 2 only in case it is specifically selected by the user.

2.2.2.1 Start Communication Request (SID 81) U.K.

DDP_005 This message is issued by the IDE to establish the communication link with the VU. Initial communications are always performed at 9 600 baud (until baud rate is eventually changed using the appropriate Link control services). U.K.

2.2.2.2 Positive Response Start Communication (SID C1) U.K.

DDP_006 This message is issued by the VU to answer positively to a start communication request. It includes the 2 key bytes ‘EA’‘8F’ indicating that the unit supports protocol with header including target source and length information. U.K.

2.2.2.3 Start Diagnostic Session Request (SID 10) U.K.

DDP_007 The Start Diagnostic Session request message is issued by the IDE in order to request a new diagnostic session with the VU. The sub function ‘default session’ (81 Hex) indicates a standard diagnostic session is to be opened. U.K.

2.2.2.4 Positive Response Start Diagnostic (SID 50) U.K.

DDP_008 The Positive Response Start Diagnostic message is sent by the VU to answer positively to Diagnostic Session Request. U.K.

2.2.2.5 Link Control Service (SID 87) U.K.

DDP_052 The Link Control Service is used by the IDE to initiate a change in baud rate. This takes place in two steps. In step one the IDE proposes the baud rate change, indicating the new rate. On receipt of a positive message from the VU the IDE sends out confirmation of the baud rate change to the VU (step two). The IDE then changes to the new baud rate. After receipt of the confirmation the VU changes to the new baud rate U.K.

2.2.2.6 Link Control Positive Response (SID C7) U.K.

DDP_053 The Link Control Positive Response is issued by the VU to answer positively to Link Control Service request (step one). Note that no response is given to the confirmation request (step two). U.K.

2.2.2.7 Request Upload (SID 35) U.K.

DDP_009 The Request Upload message is issued by the IDE to specify to the VU that a download operation is requested. To meet the requirements of ISO14229 data is included covering address, the size and format details for the data requested. As these are not known to the IDE prior to a download, the memory address is set to 0, format is unencrypted and uncompressed and the memory size is set to the maximum. U.K.

2.2.2.8 Positive Response Request Upload (SID 75) U.K.

DDP_010 The Positive Response Request Upload message is sent by the VU to indicate to the IDE that the VU is ready to download data. To meet the requirements of ISO 14229 data is included in this positive response message, indicating to the IDE that further Positive Response Transfer Data messages will include 00FF hex bytes maximum. U.K.

2.2.2.9 Transfer Data Request (SID 36) U.K.

[F1 DDP_011 The Transfer Data Request is sent by the IDE to specify to the VU the type of data that are to be downloaded. A one byte Transfer Request Parameter (TRTP) indicates the type of transfer. U.K.

There are six types of data transfer. For VU data download, two different TRTP values can be used for each transfer type:

Data transfer type	TRTP value for generation 1 type of VU data download	TRTP value for generation 2 type of VU data download
Overview	01	21
Activities of a specified date	02	22
Events and faults	03	23
Detailed speed	04	24
Technical data	05	25

Data transfer type	TRTP value
Card download	06]

[F1 DDP_054 It is mandatory for the IDE to request the overview data transfer (TRTP 01 or 21) during a download session as this only will ensure that the VU certificates are recorded within the downloaded file (and allow for verification of digital signature). U.K.

In the second case (TRTP 02 or 22) the Transfer Data Request message includes the indication of the calendar day ( format) to be downloaded.]

2.2.2.10 Positive Response Transfer Data (SID 76) U.K.

DDP_012 The Positive Response Transfer Data is sent by the VU in response to the Transfer Data Request. The message contains the requested data, with a Transfer Response Parameter (TREP) corresponding to the TRTP of the request. U.K.

[F1 DDP_055 In the first case (TREP 01 or 21), the VU will send data helping the IDE operator to choose the data he wants to download further. The information contained within this message is: U.K.

• Security certificates,

• Vehicle identification,

• VU current date and time,

• Min and Max downloadable date (VU data),

• Indication of cards presence in the VU,

• Previous download to a company,

• Company locks,

• Previous controls.]

2.2.2.11 Request Transfer Exit (SID 37) U.K.

DDP_013 The Request Transfer Exit message is sent by the IDE to inform the VU that the download session is terminated. U.K.

2.2.2.12 Positive Response Request Transfer Exit (SID 77) U.K.

DDP_014 The Positive Response Request Transfer Exit message is sent by the VU to acknowledge the Request Transfer Exit. U.K.

2.2.2.13 Stop Communication Request (SID 82) U.K.

DDP_015 The Stop Communication Request message is sent by the IDE to disconnect the communication link with the VU. U.K.

2.2.2.14 Positive Response Stop Communication (SID C2) U.K.

DDP_016 The Positive Response Stop Communication message is sent by the VU to acknowledge the Stop Communication Request. U.K.

2.2.2.15 Acknowledge Sub Message (SID 83) U.K.

DDP_017 The Acknowledge Sub Message is sent by the IDE to confirm receipt of each part of a message that is being transmitted as several sub messages. The data field contains the SID received from the VU and a 2-byte code as follows: U.K.

• MsgC+1 Acknowledges correct receipt of sub message number MsgC.

  Request from the IDE to the VU to send next sub message

• MsgC indicates a problem with the receipt of sub message number MsgC.

  Request from the IDE to the VU to send the sub message again.

• FFFF requests termination of the message.

  This can be used by the IDE to end the transmission of the VU message for any reason.

The last sub message of a message (LEN byte < 255) may be acknowledged using any of these codes or not acknowledged.

The VU responses that will consist of several sub messages are:

• Positive Response Transfer Data (SID 76)

2.2.2.16 Negative Response (SID 7F) U.K.

DDP_018 The Negative Response message is sent by the VU in response to the above request messages when the VU cannot satisfy the request. The data fields of the message contains the SID of the response (7F), the SID of the request, and a code specifying the reason of the negative response. The following codes are available: U.K.

• 10 general reject

  The action cannot be performed for a reason not covered below.

• 11 service not supported

  The SID of the request is not understood.

• 12 sub function not supported

  The DS_ or TRTP of the request is not understood, or there are no further sub messages to be transmitted.

• 13 incorrect message length

  The length of the received message is wrong.

• 22 conditions not correct or request sequence error

  The required service is not active or the sequence of request messages is not correct.

• 31 Request out of range

  The request parameter record (data field) is not valid.

• 50 upload not accepted

  The request cannot be performed (VU in a non appropriate mode of operation or internal fault of the VU).

• 78 response pending

  The action requested cannot be completed in time and the VU is not ready to accept another request.

• [F1 FA data not available

  The data object of a data transfer request are not available in the VU (e.g. no card is inserted, generation 1 type of VU data download requested outside the frame of a driver’s control by a non EU control authority…).]

2.2.3 Message flow U.K.

A typical message flow during a normal data download procedure is the following:

IDE		VU
Start Communication Request	⇨
	⇦	Positive Response
Start Diagnostic Service Request	⇨
	⇦	Positive Response
Request Upload	⇨
	⇦	Positive Response
Transfer Data Request Overview	⇨
	⇦	Positive Response
Transfer Data Request #2	⇨
	⇦	Positive Response #1
Acknowledge Sub Message #1	⇨
	⇦	Positive Response #2
Acknowledge Sub Message #2	⇨
	⇦	Positive Response #m
Acknowledge Sub Message #m	⇨
	⇦	Positive Response (Data Field < 255 Bytes)
Acknowledge Sub Message (optional)	⇨
…
Transfer Data Request #n	⇨
	⇦	Positive Response
Request Transfer Exit	⇨
	⇦	Positive Response
Stop Communication Request	⇨
	⇦	Positive Response

2.2.4 Timing U.K.

DDP_019 During normal operation the timing parameters shown in the following figure are relevant: U.K.

Figure 1

Message flow, timing

Where:

P1

=

Inter byte time for VU response.

P2

=

Time between end of IDE request and start of VU response, or between end of IDE acknowledge and start of next VU response.

P3

=

Time between end of VU response and start of new IDE request, or between end of VU response and start of IDE acknowledge, or between end of IDE request and start of new IDE request if VU fails to respond.

P4

=

Inter byte time for IDE request.

P5

=

Extended value of P3 for card downloading.

The allowed values for the timing parameters are showed in the following table (KWP extended timing parameters set, used in case of physical addressing for faster communication).

a If the VU responds with a Negative Response containing a code meaning ‘request correctly received, response pending’, this value is extended to the same upper limit value of P3.
Timing Parameter	Lower limitValue (ms)	Upper limitValue (ms)
P1	0	20
P2	20	1 000a
P3	10	5 000
P4	5	20
P5	10	20 minutes

2.2.5 Error handling U.K.

If an error occurs during the message exchange, the message flow scheme is modified depending on which equipment has detected the error and on the message generating the error.

In figure 2 and figure 3 the error handling procedures for the VU and the IDE are respectively shown.

2.2.5.1 Start Communication phase U.K.

DDP_020 If the IDE detects an error during the Start Communication phase, either by timing or by the bit stream, then it will wait for a period P3 min before issuing again the request. U.K.

DDP_021 If the VU detects an error in the sequence coming from the IDE, it shall send no response and wait for another Start Communication Request message within a period P3 max. U.K.

2.2.5.2 Communication phase U.K.

Two different error handling areas can be defined:

1.

The VU detects an IDE transmission error.

DDP_022

For every received message the VU shall detect timing errors, byte format errors (e.g. start and stop bit violations) and frame errors (wrong number of bytes received, wrong checksum byte).

DDP_023

If the VU detects one of the above errors, then it sends no response and ignores the message received.

DDP_024

The VU may detect other errors in the format or content of the received message (e.g. message not supported) even if the message satisfies the length and checksum requirements; in such a case, the VU shall respond to the IDE with a Negative Response message specifying the nature of the error.

Figure 2

VU error handling

2.

The IDE detects a VU transmission error.

DDP_025

For every received message the IDE shall detect timing errors, byte format errors (e.g. start and stop bit violations) and frame errors (wrong number of bytes received, wrong checksum byte).

DDP_026

The IDE shall detect sequence errors, e.g. incorrect sub message counter increments in successive received messages.

DDP_027

If the IDE detects an error or there was no response from the VU within a P2 max period, the request message will be sent again for a maximum of three transmissions in total. For the purposes of this error detection a sub message acknowledge will be considered as a request to the VU.

DDP_028

The IDE shall wait at least for a period of P3 min before beginning each transmission; the wait period shall be measured from the last calculated occurrence of a stop bit after the error was detected.

Figure 3

IDE error handling

2.2.6 Response Message content U.K.

This paragraph specifies the content of the data fields of the various positive response messages.

Data elements are defined in Appendix 1 data dictionary.

Remark: For generation 2 downloads, each top-level data element is represented by a record array, even if it contains only one record. A record array starts with a header; this header contains the record type, the record size and the number of records. Record arrays are named by ‘…RecordArray’ (with header) in the following tables. U.K.

2.2.6.1 Positive Response Transfer Data Overview U.K.

DDP_029 [F1 The data field of the ‘Positive Response Transfer Data Overview’ message shall provide the following data in the following order under the SID 76 Hex, the TREP 01 or 21 Hex and appropriate sub message splitting and counting:] U.K.

[F1 Data structure generation 1 (TREP 01 Hex)]
Data element		Comment
		VU Security certificates
		Vehicle identification
		VU current date and time
		Downloadable period
		Type of cards inserted in the VU
		Previous VU download
		All company locks stored. If the section is empty, only noOfLocks = 0 is sent.
		All control records stored in the VU. If the section is empty, only noOfControls = 0 is sent
		RSA signature of all data (except certificates) starting from VehicleIdentificationNumber down to last byte of last VuControlActivityData.

[F1 Data structure generation 2 (TREP 21 Hex)]
Data element		Comment
		Member state certificate
		VU certificate
		Vehicle identification
		Vehicle registration number
		VU current date and time
		Downloadable period
		Type of cards inserted in the VU
		Previous VU download
		All company locks stored. If the section is empty, an array header with noOfRecords = 0 is sent
		All control records stored in the VU. If the section is empty, an array header with noOfRecords = 0 is sent
		ECC signature of all preceding data except the certificates.

2.2.6.2 Positive Response Transfer Data Activities U.K.

DDP_030 [F1 The data field of the ‘Positive Response Transfer Data Activities’ message shall provide the following data in the following order under the SID 76 Hex, the TREP 02 or 22 Hex and appropriate sub message splitting and counting:] U.K.

[F1 Data structure generation 1 (TREP 02 Hex)]
Data element		Comment
		Date of day downloaded
		Odometer at end of downloaded day
		Cards insertion withdrawal cycles data. If this section contains no available data, only noOfVuCardIWRecords = 0 is sent. When a VuCardIWRecord lies across 00:00 (card insertion on previous day) or across 24:00 (card withdrawal the following day) it shall appear in full within the two days involved.
		Slots status at 00:00 and activity changes recorded for the day downloaded.
		Places related data recorded for the day downloaded. If the section is empty, only noOfPlaceRecords = 0 is sent.
		Specific conditions data recorded for the day downloaded. If the section is empty, only noOfSpecificConditionRecords=0 is sent
		RSA signature of all data starting from TimeReal down to last byte of last specific condition record.

[F1 Data structure generation 2 (TREP 22 Hex)]
Data element		Comment
		Date of day downloaded
		Odometer at end of downloaded day
		Cards insertion withdrawal cycles data. If this section contains no available data, an array header with noOfRecords = 0 is sent. When a VuCardIWRecord lies across 00:00 (card insertion on previous day) or across 24:00 (card withdrawal the following day) it shall appear in full within the two days involved.
		Slots status at 00:00 and activity changes recorded for the day downloaded.
		Places related data recorded for the day downloaded. If the section is empty, an array header with noOfRecords = 0 is sent.
[F1		GNSS positions of the vehicle when the accumulated driving time of the vehicle reaches a multiple of three hours. If the section is empty, an array header with noOfRecords = 0 is sent.]
		Specific conditions data recorded for the day downloaded. If the section is empty, an array header with noOfRecords =0 is sent
		ECC signature of all preceding data.

2.2.6.3 Positive Response Transfer Data Events and Faults U.K.

DDP_031 [F1 The data field of the ‘Positive Response Transfer Data Events and Faults’ message shall provide the following data in the following order under the SID 76 Hex, the TREP 03 or 23 Hex and appropriate sub message splitting and counting:] U.K.

[F1 Data structure generation 1 (TREP 03 Hex)]
Data element		Comment
		All faults stored or on-going in the VU. If the section is empty, only noOfVuFaults = 0 is sent.
		All events (except over speeding) stored or on-going in the VU. If the section is empty, only noOfVuEvents = 0 is sent.
		Data related to last over speeding control (default value if no data).
		All over speeding events stored in the VU. If the section is empty, only noOfVuOverSpeedingEvents = 0 is sent.
		All time adjustment events stored in the VU (outside the frame of a full calibration). If the section is empty, only noOfVuTimeAdjRecords = 0 is sent.
		RSA signature of all data starting from noOfVuFaults down to last byte of last time adjustment record

[F1 Data structure generation 2 (TREP 23 Hex)]
Data element		Comment
		All faults stored or on-going in the VU. If the section is empty, an array header with noOfRecords = 0 is sent.
		All events (except over speeding) stored or on-going in the VU. If the section is empty, an array header with noOfRecords = 0 is sent.
		Data related to last over speeding control (default value if no data).
		All over speeding events stored in the VU. If the section is empty, an array header with noOfRecords = 0 is sent.
		All time adjustment events stored in the VU (outside the frame of a full calibration). If the section is empty, an array header with noOfRecords = 0 is sent.
[ F3 ]
		ECC signature of all preceding data.

2.2.6.4 Positive Response Transfer Data Detailed Speed U.K.

DDP_032 [F1 The data field of the ‘Positive Response Transfer Data Detailed Speed’ message shall provide the following data in the following order under the SID 76 Hex, the TREP 04 or 24 Hex and appropriate sub message splitting and counting:] U.K.

[F1 Data structure generation 1 (TREP 04)]
Data element		Comment
		All detailed speed stored in the VU (one speed block per minute during which the vehicle has been moving) 60 speed values per minute (one per second).
		RSA signature of all data starting from noOfSpeedBlocks down to last byte of last speed block.

[F1 Data structure generation 2 (TREP 24)]
Data element		Comment
		All detailed speed stored in the VU (one speed block per minute during which the vehicle has been moving) 60 speed values per minute (one per second).
		ECC signature of all preceding data.

2.2.6.5 Positive Response Transfer Data Technical Data U.K.

DDP_033 [F1 The data field of the ‘Positive Response Transfer Data Technical Data’ message shall provide the following data in the following order under the SID 76 Hex, the TREP 05 or 25 Hex and appropriate sub message splitting and counting:] U.K.

[F1 Data structure generation 1 (TREP 05)]
Data element		Comment
		All calibration records stored in the VU.
		RSA signature of all data starting from vuManufacturerName down to last byte of last VuCalibrationRecord.

[F1 Data structure generation 2 (TREP 25)]
Data element		Comment
		All MS pairings stored in the VU
		All external GNSS facility couplings stored in the VU
		All calibration records stored in the VU.
		All card insertion data stored in the VU.
		ECC signature of all preceding data.