ISO 15765-4 pdf download – Road vehicles – Diagnostics on Controller Area Networks (CAN)—Part 4: Requirements for emissions-related systems

ISO 15765-4 pdf download – Road vehicles – Diagnostics onController Area Networks (CAN)—Part 4: Requirements for emissions-related systems.
For legislated-OBD baudrates, the external test equipment shall use the appropriate CAN bit timing parameter values defined in 83
The folowing descriptions of the external test equipment initiakzation make use of the connectors A to F as shown in Figure 1 to reference certain entry arid exit ponts.
4.2 11 bit CAN identifier verification procedure
4.2.1 Request message transmit poc.dur.
The purpose of the 11 bit CAN identifier verification procedure is to determine whether 11 bit CAN identifiers are being used in Iegislated-OBD communication and, if multiple baudrates are specified in the baudrateRecord parameter, to determine the baudrate to be used 11 such communication.
The folowing transmit procedure shall be used to transmit the request message CA the 11 bit CAN identifier verification procedure. The transmit procedure contains provisions for legacy vehicles which use either CAN (same or different physical layer as defined for legislated OBD) or a different protocol (non CAN) on the CAN pins of the ISO 15031-3 diagnostic connector.
Where the vehicle uses a CAN with a physical layer different from that specified for legislated OBO (Clause 8) or a non-CAN protocol on the CAN pins of the OBD connector, the transmit procedure given as follows shall guarantee that in all cases the external test equipment will detect that the vehicle does not support CAN as specified for legislated 080 and will stop the transmission of the request message immediately.
Where the vehicle uses CAN and the physical Layer according to Clause 8. the transmit procedure given as follows shall guarantee that in all cases the external test equipment will detect that it uses the wrong baudrate for the transmission of the request message and will stop disturbing the CAN bus immediately. Under normal in-vehicle conditions (i.e. no error frames during in-vehicle communication when the external test equment is disconnected), the external test equipment will disable its CAN interface prior to the situation where the internal error counters of the 080 ECU(S) reach critical values.
To achieve this, the external test equipment shall support the following features.
Possibdity to stop sending immediately duflng transmission of any CAN frame The CAN interface should be disconnected within 12 ps from reception of a bus error signal. The maximum time for the disconnection is 100 ps. With the CAN interface disconnected, the external test equipment shal not be able to transmit dominant bets on the CAN bus.
– Possibility to immediately detect any error on the CAN bus. The procedure shall be performed as follows See Figure 2.
a) The external test equipment shall set up its CAN interface using the first baudrate contained in the baudrateRecord. It shall use the CAN bit timing parameter values defined for this baudrate (see 8.3). Following the CAN Interface set-up, it shall connect the CAN Interface to the CAN bus.
b) The external test equipment shall transmit a functionalty addressed service 01 hex request message (read-supported PIDs)21 using the leg islated-OBO 11 bit functional request CAN identifier according to 6.32.2.
d) If at least one response message is started, the external test equipment shall continue to receive this previously started response message (only applies to multiple-frame response messages) and shall accept further response messages within 2N which use one of the specified legislated•O8D 11 bIt physical response CAN identifiers,
e) When all started response messages are completely received (positive or negative responses) and the p2c application timer is timed out, this means that the external test equipment has verified that the vehicle supports legislated OBO on CAN using 11 bit CAN identifiers (connector E), If all received response messages are positive response messages, then the external test equipment knows the supported PIDs and the communication parameters of the legislated-OBO ECUs expected to respond to servIce 01 hex data parameter requests. Where one or more of the received response messages are negative response messages with response code 21 hex (busyRepeatRequest), the external test equipment shal start the initialization sequence (Connector A) again after a minimum delay of 200 ms. If the negative response(s) appear(s) on six (6) subsequent sequences, the external test eqspment will assume that the vehicle is not compliant wtth ISO 15765-4 (connector F). This means that the legislated OBD-related ECU(S) shall provide a positive response withe, a maximum of five retries.