ISO / DIS Road Vehicles - Diagnostic Systems ISO / DIS - 2: KEYWORD PROTOCOL - PART 2: DATA LINK LAYER. ISO specifies data link layer services tailored to meet the requirements of UART-based vehicle communication systems on K-Line as specified in. ISO. First edition. Road vehicles - Diagnostic systems- Details of the software products used to create this PDF file can be found in the.
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de données. STANDARD. ISO. Third edition. Reference number. ISO (E). This document is a preview generated by EVS. ISO All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means. there are many types of diagnostic systems defined by ISO and SAE . ISO  specifies common requirements of diagnostic services which allow a tester.
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Changes are indicated by changing the font from "Arial" to "Times New Roman"! It has been established in order to define common requirements for the implementation of diagnostic services for diagnostic systems.
To achieve this, the standard is based on the Open System Interconnection O: Basic Reference Model in accordance with ISO which structures communication systems into seven layers. When mapped on this model, the services used by a diagnostic tester and an Electronic Control Unit ECU are broken into: Application Diagnostic Data Service. Scope This national Standard specifies common requirements of diagnostic services which allow a tester to control diagnostic functions in an on-vehicle Electronic Control Unit e.
It specifies only layer 2 data link layer. Included are all definitions which are necessary to implement the services described in "Keyword Protocol - Part 3: Implementation on a serial link described in "Keyword Protocol - Part 1: This Standard does not specify the requirements for the implementation of diagnostic services. The physical layer may be used as a multi-user-bus, so a kind of arbitration or bus management is necessary. If arbitration is used it shall comply to the technique described in Attachment A.
The car manufacturers are responsible for the correct working of bus management. Communication between ECUs are not part of this document. The vehicle diagnostic architecture of this standard applies to: This document applies to the diagnostic communications over the diagnostic data link; the diagnostic communications over the internal data link may conform to this document or to another protocol.
In vehicle 2, the ECUs are directly connected to the diagnostic data link. Normative Reference The following standards contain provisions which, through reference in this text, constitute provisions of this document. All standards are subject to revision, and parties to agreement based on this document are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. ISO Dec, SAEJ June, ISO Physical topology Keyword Protocol is a bus concept s.
Figure 3 shows the general form of this serial link. Special cases are node-to-nodeconnections, that means there is only one ECU on the line, which also can be a bus converter. Message structure This section describes the structure of a message.
The message structure consists of three parts: The area of data bytes always begins with a Service Identification. Use of the data bytes for communication services is described in this document. Use of the data bytes for diagnostic services is described in "Keyword Protocol - Part 3: A format byte includes information about the form of the message.
A separate length byte allows message lengths up to bytes. The tester is informed about use of header bytes by the key bytes s. Define the form of the header which will be used by the message: Define the length of the data field of a message, i. A message length of 1 to 63 bytes is possible. It may be a physical or a functional address. Requirements For Emission related Systems.
The target address of a physically addressed request shall be interpreted as a physical server ECU address, the source address is the physical address of the client tester. In the response message the target and source addresses are also physical addresses HM2. Physical addresses shall be according to SAE JPart 1, or as specified by the vehicle manufacturer.
The target address of a functionally addressed request shall be interpreted as a functional group address, the source address is the physical address of the client tester. In the response messages the target and source addresses are physical addresses, i. Functional addressing requires that the servers ECUs must support arbitration see appendix A.
It must be a physical address also in the case where the target address is a functional address. There are the same possibilities for the values as described for physical target address bytes. It allows the user to transmit messages with data fields longer then 63 bytes. With shorter messages it may be omitted. This byte defines the length of the data field of a message, i. A data length of 1 to bytes is possible. For messages with data fields of less than 64 bytes there are two possibilities: Length may be included in the format byte or in the additional length byte.
An ECU may support both possibilities, the tester is informed about this capability through the keybytes see section 5. These are shown diagramatically below. The first byte of the data field is the Service Identification Byte. It may be followed by parameters and data depending on the selected service. These bytes are defined in "Keyword Protocol - Part 3: Implementation" for diagnostic services and in section 5 of this document for communication services.
Tester request P 4 ECU 1 response Time between end of ECU response and start of new tester request, or time between end of tester request and start of new tester request if ECU fails to respond. P3 shall be measured from the last byte in the latest response message from any ECU responding. Inter byte time in tester request. There are two sets of default timing parameters, normal and extended. Only normal timing parameters are supported by this document Swedish Implementation Standard.
Table 1a shows the timing parameters which are used as default all values in ms. The P2max timing parameter value shall always be a single byte value in the AccessTimingParameter service. The timing modifications shall be activated by implementation of the AccessTimingParameter service. Users must take care for limits listed above and the following restrictions: He also has to make sure that the chosen communication parameters are possible for all ECUs which participate in the session.
The possible values depend on the capabilities of the ECU. In some cases the ECU possibly needs to leave its normal operation mode for switching over to a session with different communication parameters. For complete timing diagrams see appendix B. This response code shall only be used by a server in case it cannot send a positive or negative response message based on the client's request message within the active P2 timing window.
PeriodicTransmission shall be supported in connection with physical addressing, normal and modified timing. The description below explains in steps how the PeriodicTransmission mode shall be activated, handled and de-activated.
Step 1: To enable the PeriodicTransmission mode in the client tester and the server ECU the client tester shall transmit a startDiagnosticSession request message containing the diagnosticMode parameter for the PeriodicTransmission. After the reception of the first positive response message from the server ECU the PeriodicTransmission mode is enabled and periodic transmission mode communication structure and timing becomes active.
The timing parameters can be changed within the possible limits of the periodic transmission timing parameter set see Table 1d with the communication service AccessTimingParameters. After reception of a stopDiagnosticSession or stopComunication positive response message the periodicTransmissionMode is disabled and the default diagnostic session with the default timing values, defined by the key bytes becomes active.
After reception of a stopDiagnosticSession or stopComunication negative response message the periodicTransmissionMode shall continue. Step 2: Step 3: It is important for the client tester to guarantee a minimum size of the jump-in window for the start of a request message.
P1max shall not exceed P2min. This is required in order to support resynchronisation between the server ECU and client tester to meet the error handling requirements.
Default and optimised timing parameter values The timing table below specifies the timing parameter values with the diagnostic mode standardDiagnosticModeWithPeriodicTransmission. Table 1d - Timing parameter - periodic transmission. All values in ms Timing minimum values Parameter lower limit default resolution 1 P1 0 P2 7 0. When implementing the standardDiagnosticModeWithPeriodicTransmission the following limits and restrictions must be considered as listed below: For complete timing diagrams and message flow examples see appendix B and C.
The data segments shall be transmitted consecutively in repeated response messages. Each message shall be transmitted within the timing window P2.
The data field of each response message shall consist of the Service ID and the corresponding data segment see figure 5. Data segmentation shall be detected by the client tester by comparing source addresses and Service IDs which must be identical for all response messages during segmentation.
Server ECU response data segmentation shall only be used when the data length exceeds the maximum length that the server ECU can transmit in a single message.
Data segmentation shall not be supported in periodic transmission mode. Requirements For Emission Related Systems. If data segmentation is used the following restriction shall apply: HM2 Target address: Length of data segment Data i.
Header i: Number of bytes received equals message length as defined in the format byte or length byte or Time-out of inter byte time in the received message P1max exceeded in ECU transmission, P4max exceeded in tester transmission whichever occurs first. Communication services Some services are necessary to establish and maintain communication.
They are not diagnostic services because they do not appear on the application layer. A description of implementation on the physical layer of Keyword Protocol is added. In order to perform any diagnostic service, communication must be initialised and the communication parameters need to be appropriate to the desired diagnostic mode.
A chart describing this is shown in figure 6. N o AccessComm. Communication Service 2: Valid conditions for the initialisation of a diagnostic communication link are described in section 5. Then the ECU shall perform all actions necessary to initialise the communication link and send a StartCommunication response primitive with the Positive Response parameters selected.
If the communication link cannot be initialised by any reason, the ECU shall maintain its normal operation. There are general facts that applies to the fast initialisation procedure: Application layer — Part 4: Requirements for emissions-related systems Annex A of this part of ISO is given for information only. Subcommittee SC 3. ISO consists of the following parts. International organizations.
Electrical and electronic equipment. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Road vehicles — Diagnostic systems — Keyword protocol — Part 2: Data link layer.
Road vehicles — Diagnostic systems — Requirements for interchange of digital information. Road vehicles — Electrical disturbance by conduction and coupling — Part 2: Commercial vehicles with nominal 24 V supply voltage — Electrical transient conduction along supply lines only. Road vehicles — Communication between vehicle and external equipment for emissions-related diagnostics— Part 3: Diagnostic connector and related electrical circuit: Road vehicles — Diagnostic systems — Keyword protocol — Part 3: Application layer.
It is based on the physical layer described in ISO All standards are subject to revision. At the time of publication. Road vehicles — Electrical disturbance by conduction and coupling — Part 1: Passenger cars and light commercial vehicles with nominal 12 V supply voltage — Electrical transient conduction along supply lines only.
The arrows indicate the direction of data flow. Figure 1 — Possible system configurations 4. After conveying this information. If lines K and L are used for purposes other than inspection.. Line L is a unidirectional line and is only used during initialization to convey address information or.
Line K is a bidirectional line. This includes the completion of the initialization sequence and all other communication services as described in ISO and the subsequent communication as described in ISO and ISO Figure 1 shows the system configurations allowed. Vehicle battery voltage.
It is used during initialization to convey address information or. At all other times.
For example. On other vehicles without ground and supply pins. NRZ coding shall be used.. In addition. Figure 2 illustrates the worst case on signal levels. For electrical specifications of diagnostic testers. The capacitance contribution of the on-board wiring is termed COBW. The sum of the input capacitance of all the ECUs on the bus is defined thus: When the diagnositc tester is linked to an ECU. Manufacturers of diagnostic testers are encouraged to extend these limits of correct operation for vehicle battery voltage VB and working temperature.
The formula to be used is given in ISO They apply to nominal 12 V 24 V systems for which the diagnostic tester shall operate correctly in the range 8 V to 16 V 16 V to 32 V of the vehicle battery voltage VB. These values are derived from the circuit resistance and baud rate tolerances sees clauses 6 and 7.
Values for CECU.. If a higher or lower maximum communication speed is chosen then the designer will reduce or increase the allowed capacitance accordingly. In addition the sink resistance shall be designed so the slope time of the falling edge is as in 5. This value shall not exceed the limits specified in 5. In case of problems e. When the serial communication of the ECU is not in operation and the diagnostic tester is connected. VB and ground shall also be made available to the tester but need not come directly from the ECU.
The 5 baud address shall be transmitted with a tolerance of 6 0. No capacitance value per ECU is given for 24 V systems. This value may change if a different number of ECUs are connected. If an internal resistance is used between line K and VB. If an internal resistance is used between line L and VB.. VB and ground shall be made available to the diagnostic tester but need not come directly from an ECU.