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

4.1. StartCommunication Service U.K.

CPR_006 Upon receiving a StartCommunication indication primitive, the VU shall check if the requested communication link can be initialised under the present conditions. Valid conditions for the initialisation of a communication link are described in document ISO 14230-2. U.K.

CPR_007 Then the VU shall perform all actions necessary to initialise the communication link and send a StartCommunication response primitive with the Positive Response parameters selected. U.K.

CPR_008 If a VU that is already initialised (and has entered any diagnostic session) receives a new StartCommunication Request (e.g. due to error recovery in the tester) the request shall be accepted and the VU shall be reinitialised. U.K.

CPR_009 If the communication link cannot be initialised for any reason, the VU shall continue operating as it was immediately prior to the attempt to initialise the communication link.. U.K.

CPR_010 The StartCommunication Request message must be physically addressed. U.K.

CPR_011 Initialising the VU for services is performed through a ‘fast initialisation’ method, U.K.

• There is a bus-idle time prior to any activity.

• The tester then sends an initialisation pattern.

• All information which is necessary to establish communication is contained in the response of the VU.

CPR_012 After completion of the initialisation, U.K.

• All communication parameters are set to values defined in Table 4 according to the key bytes.

• The VU is waiting for the first request of the tester.

• The VU is in the default diagnostic mode, i.e. StandardDiagnosticSession.

• The calibration I/O signal line is in the default state, i.e. disabled state.

CPR_014 The data rate on the K-line shall be 10 400 Baud. U.K.

CPR_016 The fast initialisation is started by the tester transmitting a Wake up pattern (Wup) on the K-line. The pattern begins after the idle time on K-line with a low time of Tinil. The tester transmits the first bit of the StartCommunication Service after a time of Twup following the first falling edge. U.K.

CPR_017 The timing values for the fast initialisation and communications in general are detailed in the tables below. There are different possibilities for the idle time: U.K.

• First transmission after power on, Tidle = 300 ms.

• After completion of a StopCommunication Service, Tidle = P3 min.

• After stopping communication by time-out P3 max, Tidle = 0.

Table 3
Timing values for fast initialisation
Parameter		min value	max value
Tinil	25 ± 1 ms	24 ms	26 ms
Twup	50 ± 1 ms	49 ms	51 ms

Table 4
Communication timing values
Timing Parameter	Parameter Description	lower limit values [ms]	upper limit values [ms]
		min.	max.
P1	Inter byte time for VU response	0	20
P2	Time between tester request and VU response or two VU responses	25	250
P3	Time between end of VU responses and start of new tester request	55	5 000
P4	Inter byte time for tester request	5	20

CPR_018 The message format for fast initialisation is detailed in the following tables. (NOTE: Hex means hexadecimal) U.K.

Table 5
StartCommunication Request Message
Byte #	Parameter Name	Hex Value	Mnemonic
#1	Format byte — physical addressing	81	FMT
#2	Target address byte	EE	TGT
#3	Source address byte	tt	SRC
#4	StartCommunication Request Service Id	81	SCR
#5	Checksum	00-FF	CS

Table 6
StartCommunication Positive Response Message
Byte #	Parameter Name	Hex Value	Mnemonic
#1	Format byte — physical addressing	80	FMT
#2	Target address byte	tt	TGT
#3	Source address byte	EE	SRC
#4	Additional length byte	03	LEN
#5	StartCommunication Positive Response Service Id	C1	SCRPR
#6	Key byte 1	EA	KB1
#7	Key byte 2	8F	KB2
#8	Checksum	00-FF	CS

CPR_019 There is no negative response to the StartCommunication Request message, if there is no positive response message to be transmitted then the VU is not initialised, nothing is transmitted and it remains in its normal operation. U.K.