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

4.4. Message Format U.K.

All messages exchanged between the ITS Unit and the VU interface shall be formatted with a structure consisting of three parts: A header composed by a target byte (TGT), a source byte (SRC) and a length byte (LEN).

The data field composed by a service identifier byte (SID) and a variable amount of data bytes (maximum 255).

The checksum byte is the 1 byte sum series modulo 256 of all the bytes of the message excluding the CS itself.

The message shall be Big Endian.

Table 2

General message format

Header			Data Field					Checksum
TGT	SRC	LEN	SID	TRTP	CC	CM	DATA	CS
3 bytes			Max. 255 bytes					1 byte

Header U.K.

TGT and SRC: the ID of the Target (TGT) and Source (SRC) devices of the message. The VU Interface shall have the default ID “EE”. This ID cannot be changed. The ITS Unit shall use the default ID “A0” for its first message of the communication session. The VU Interface shall then assign an unique ID to the ITS Unit and informs it of this ID for future messages during the session.

The LEN byte shall only take into account the ‘DATA’ part of the Data Field (see Table 2), the 4 first bytes are implicit.

The VU Interface shall confirm the authenticity of the message's sender by cross-checking its own IDList with the Bluetooth data by checking the ITS Unit listed at the provided ID is currently in the range of the Bluetooth connection.

Data Field U.K.

Besides the SID, the Data Field shall also contain other parameters: a transfer request parameter (TRTP) and Counter bytes.

[F1 If the data to be handled is larger than the available space in one message, it will be split in several submessages. Each submessage shall have the same Header and SID, but will contain a 2-bytes counter, Counter Current (CC) and Counter Max (CM), to indicate the submessage number. To enable error checking and abort the receiving device acknowledges every submessage. The receiving device can accept the submessage, ask for it to be re-transmitted, request the sending device to start again or abort the transmission.]

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).

If not used, CC and CM shall be given the value 0xFF.

For instance, the following message

HEADER	SID	TRTP	CC	CM	DATA	CS
3 bytes	Longer than 255 bytes					1 byte

Shall be transmitted as such:

HEADER	SID	TRTP	01	n	DATA	CS
3 bytes	255 bytes					1 byte

HEADER	SID	TRTP	02	n	DATA	CS
3 bytes	255 bytes					1 byte

…

HEADER	SID	TRTP	N	N	DATA	CS
3 bytes	Max. 255 bytes					1 byte

Table 3 contains the messages the VU and the ITS Unit shall be able to exchange. The content of each parameter is given in hexadecimal. Aren't represented in the table CC and CM for clarity, see above for complete format.

Table 3

Detailed message content

Message	Header			DATA			Checksum
	TGT	SRC	LEN	SID	TRTP	DATA
RequestPIN	ITSID	EE	00	01	FF
SendITSID	ITSID	EE	01	02	FF	ITSID
SendPIN	EE	ITSID	04	03	FF	4*INTEGER (0..9)
PairingResult	ITSID	EE	01	04	FF	BOOLEAN (T/F)
SendPUC	EE	ITSID	08	05	FF	8*INTEGER (0..9)
BanLiftingResult	ITSID	EE	01	06	FF	BOOLEAN (T/F)
RequestRejected	ITSID	EE	08	07	FF	Time
RequestData
standardTachData	EE	ITSID	01	08	01
personalTachData	EE	ITSID	01	08	02
gnssData	EE	ITSID	01	08	03
standardEventData	EE	ITSID	01	08	04
personalEventData	EE	ITSID	01	08	05
standardFaultData	EE	ITSID	01	08	06
manufacturerData	EE	ITSID	01	08	07
ResquestAccepted	ITSID	EE	Len	09	TREP	Data
DataUnavailable
No data available	ITSID	EE	02	0A	TREP	10
Personal data not shared	ITSID	EE	02	0A	TREP	11
NegativeAnswer
General reject	ITSID	EE	02	0B	SID Req	10
Service not supported	ITSID	EE	02	0B	SID Req	11
Sub function not supported	ITSID	EE	02	0B	SID Req	12
Incorrect message length	ITSID	EE	02	0B	SID Req	13
Conditions not correct or request sequence error	ITSID	EE	02	0B	SID Req	22
Request out of range	ITSID	EE	02	0B	SID Req	31
Response pending	ITSID	EE	02	0B	SID Req	78
ITSID Mismatch	ITSID	EE	02	0B	SID Req	FC
ITSID Not Found	ITSID	EE	02	0B	SID Req	FB

RequestPIN (SID 01) U.K.

This message is issued by the VU Interface if a non-blacklisted but non-whitelisted ITS unit is sending any data request.

SendITSID (SID 02) U.K.

This message is issued by the VU Interface whenever a new device is sending a request. This device shall use the default ID “A0” before getting assigned an unique ID for the communication session.

SendPIN (SID 03) U.K.

This message is issued by the ITS Unit to be whitelisted from the VU interface. The content of this message is a 4 INTEGER between 0 and 9 code.

PairingResult (SID 04) U.K.

This message is issued by the VU Interface to inform the ITS Unit if the PIN code it sent was correct. The content of this message shall be a BOOLEAN with the value ‘True’ if the PIN code was correct and ‘False’ otherwise.

SendPUC (SID 05) U.K.

This message is issued by the ITS Unit to lift a blacklist sanction from the VU interface. The content of this message is a 8 INTEGER between 0 and 9 code.

BanLiftingResult (SID 06) U.K.

This message is issued by the VU Interface to inform the ITS Unit if the PUC code it sent was correct. The content of this message shall be a BOOLEAN with the value ‘True’ if the PUC code was correct and ‘False’ otherwise.

RequestRejected (SID 07) U.K.

This message is issued by the VU Interface as a reply to any message from a blacklisted ITS Unit except ‘SendPUC’. The message shall contain the remaining time the ITS Unit is blacklisted, following the ‘Time’ sequence format as defined in Annex 3.

RequestData (SID 08) U.K.

This message for data accessing is issued by the ITS Unit. A one byte transfer request parameter (TRTP) indicates the type of data required. There are several types of data:

• standardTachData (TRTP 01): Data available from the tachograph classified as non-personal.

• personalTachData (TRTP 02): Data available from the tachograph classified as personal.

• gnssData (TRTP 03): GNSS data, always personal.

• standardEventData (TRTP 04): Recorded event data classified as non-personal.

• personalEventData (TRTP 05): Recorded event data classified as personal.

• standardFaultData (TRTP 06): Recorded faults classified as non-personal.

• manufacturerData (TRTP 07): data made available by the manufacturer.

See Annex 3 of this appendix for more information about the content of each data type.

See Appendix 12 for more information about the format and content of GNSS data.

See Annex IB and IC for more information about event data code and faults.

ResquestAccepted (SID 09) U.K.

This message is issued by the VU Interface if a ITS Unit ‘RequestData’ message has been accepted. This message contains a 1-byte TREP, which is the TRTP byte of the associated RequestData message, and all the data of the requested type.

DataUnavailable (SID 0A) U.K.

This message is issued by the VU Interface if, for a certain reason, the requested data aren't available to be sent to a whitelisted ITS Unit. The message contains a 1byte TREP which is the TRTP of the required data and a 1 byte error code specified in the table 3. The Following codes are available:

• No data available (10): The VU interface can't access the VU data for unspecified reasons.

• Personal data not shared (11): The ITS Unit tries to retrieve personal data when they are not shared.

NegativeAnswer (SID 0B) U.K.

These messages are issued by the VU Interface if a request cannot be completed for any other reason than the unavailability of the data. These messages are typically the result of a bad request format (Length, SID, ITSID…) but aren't limited to that. The TRTP in the Data Field contains the SID of the request. The Data Field contains a code identifying the reason of the negative answer. The following codes are available:

• General Reject (code: 10)

• The action can't be performed for a reason which isn't cited below nor in section (Enter DataUnavailable section number).

• Service not supported (code: 11)

• The request's SID isn't understood.

• Sub function not supported (code: 12)

• The request's TRTP isn't understood. It can be for instance missing or out of accepted values.

• Incorrect message length (code: 13)

• The length of the received message is wrong (mismatch between the LEN byte and the actual message length).

• Conditions not correct or request sequence error (code: 22)

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

• Request out of range (code: 33)

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

• Response pending (code: 78)

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

• ITSID Mismatch (code: FB)

• The SRC ITSID doesn't match the associated device after comparison with the Bluetooth information.

• ITSID Not Found (code: FC)

• The SRC ITSID isn't associated with any device.

Lines 1 through 72 (FormatMessageModule) of the ASN.1 code in Annex 3 specify the messages format as described in table 3. More details about the messages content is given below.