Diagnostic & Vehicle Network Protocols Table

SAE J1850 (SAE)

• SAE J1850 defines two physical layers: one optimised for 10.4 kbit/s and one for 41.6 kbit/s.
• California OBD II rules: J1850 may not be used on any 2008 or later model-year vehicle; OBD messages must use the CRC and the three-byte header.
• On the J1962 connector, J1850 uses pin 2 (Bus+) and, for PWM, pin 10 (Bus-).

Sources [1, 10, 12]

SAE J1850 (SAE)

• The 10.4 kbit/s physical layer of SAE J1850.
• Not allowed on 2008 or later model-year vehicles under 13 CCR 1968.2(g)(3.1).

Sources [1, 10, 12]

ISO 9141-2:1994 (ISO)

• ISO's abstract: limited to vehicles with a nominal 12 V supply; a subset of ISO 9141:1989 written to meet California's OBD II rule.
• Not allowed on 2008 or later model-year vehicles under 13 CCR 1968.2(g)(3.2).
• The ELM327 datasheet lists it as '5 baud init, 10.4 kbaud' and notes the K and L lines use 510 ohm pull-ups, as the standard requires.

Sources [1, 10, 11]

ISO 14230-4:2000 (ISO)

• Keyword Protocol 2000 requirements for emission-related OBD; the full protocol is ISO 14230-1 to -3.
• ISO 14230-1:2012 (the physical layer) extends the ISO 9141-2 physical layer to 12 V and 24 V vehicles.
• Not allowed on 2008 or later model-year vehicles under 13 CCR 1968.2(g)(3.3).

Sources [1, 10, 11]

ISO 15765-4:2021 (ISO)

• Allowed from model year 2003 and required on all 2008 and later model-year vehicles in California's OBD II rule, which US EPA rules adopt; emission messages must use 500 kbit/s.
• The ELM327 data sheet lists four CAN variants for it: 11-bit or 29-bit identifiers at 500 or 250 kbit/s (its protocols 6 to 9).
• EU: Euro 6 vehicles must use ISO 15765-4 as the OBD link (Regulation (EC) No 692/2008, Annex XI, Appendix 1, 2.5).
• ISO lists the 2021 edition as current and under systematic review.

Sources [1, 4, 9, 10, 11]

SAE J1979 (SAE); ISO 15031-5:2015

• SAE describes J1979 and ISO 15031-5 as one set covering communication between the vehicle's OBD systems and test equipment for legislated OBD.
• California requires J1979 for the standardised OBD functions on 2003 to 2026 model-year vehicles that use ISO 15765-4.

Sources [1, 11, 13]

SAE J1979-2:2021 (SAE)

• 13 CCR 1968.2(d)(9.2): manufacturers may use J1979-2 instead of J1979 on 2023 to 2026 model years and must use it from model year 2027; it may not be used on 2022 and earlier vehicles.
• Under J1979-2 the vehicle answers UDS-style requests (Service $19 for DTCs, $22 for data, $14 to clear), so the scan tool must support J1979-2.
• US EPA may approve J1979-2 for heavy-duty engines where CARB has approved it (40 CFR 1036.150(v)).

Sources [1, 6]

SAE J1962:2016; ISO 15031-3:2023

• SAE J1962 is technically equivalent to ISO/DIS 15031-3; ISO 15031-3:2023 references the latest J1962 and adds requirements for right-hand-drive vehicles.
• California: Type A connector in the driver's foot-well, no higher than the bottom of the steering wheel; any power pin must be fused and may not exceed 20.0 V DC whatever the vehicle voltage.
• From model year 2021 (phased in from 2019) the connector may not be covered and its mounting must withstand 220 N.

Sources [1, 11, 14]

Directive 98/69/EC; Reg. (EC) 692/2008

• Directive 98/69/EC required OBD on M1 and N1 petrol (positive-ignition) vehicles; its new type-approval dates were 1 January 2000 (M up to 2500 kg and N1 class I) and 1 January 2001 (other N1 and heavier M).
• Diesel M1 cars (up to 6 occupants and 2500 kg) needed OBD from 1 January 2003 for new types and 1 January 2004 for all types.
• As adopted, 98/69/EC allowed ISO 9141-2, ISO 11519-4 (SAE J1850) or ISO DIS 14230-4 and an ISO DIS 15031-3 connector; for Euro 6 vehicles Regulation 692/2008 requires ISO 15765-4.

Sources [8, 9]

40 CFR 86.010-18; 13 CCR 1971.1

• From model year 2013 every OBD module on a vehicle must use one protocol: ISO 15765-4 at 500 kbit/s, or SAE J1939, which may only be used with diesel engines (40 CFR 86.010-18(k)(3)).
• The connector is SAE J1962 Type A when ISO 15765-4 is used and SAE J1939-13 when J1939 is used.
• From model year 2027 the federal heavy-duty OBD requirements move to 40 CFR 1036.110.
• California 13 CCR 1971.1: J1939 OBD messages may use 250 or 500 kbit/s on 2010 to 2015 engines; 250 kbit/s may not be used from model year 2016.

Sources [2, 5]

ISO 27145-1 to -6 (2012-2023)

• ISO says 27145 is intended to become the single communication standard for OBD information, starting on DoCAN (ISO 15765-4) and moving to DoIP (ISO 13400).
• A WWH-OBD test tool first determines whether the vehicle uses legislated OBD (ISO 15031 on DoCAN) or WWH-OBD (ISO 27145 on DoCAN or DoIP).

Sources [11]

ISO 14229-1:2026 (ISO)

• Data-link-independent diagnostic services: read and clear DTCs, read identification and live data, control actuators, start and stop routines.
• Bus-specific parts: 14229-3 UDS on CAN (2022), -4 on FlexRay (2012), -5 on IP (2022), -6 on K-Line (2013), -7 on LIN (2022), -8 on CXPI (2020).
• ISO 15765-3:2004 (UDS on CAN) is withdrawn; ISO lists ISO 14229-3:2012 as its replacement.

Sources [11]

ISO 15765-2:2024 (ISO)

• Splits diagnostic messages longer than one CAN frame into segments; ISO lists it as serving enhanced diagnostics, OBD (ISO 15031 / SAE J1979), WWH-OBD (ISO 27145) and ISO 26021.
• It does not decide whether CAN CC, CAN FD or both are used; that is left to the standards that reference it.

Sources [11]

ISO 15765-3:2004, withdrawn

• Specified UDS (ISO 14229-1) on CAN. ISO's catalogue shows it withdrawn and replaced by ISO 14229-3:2012.

Sources [11]

ISO 13400-2:2025 (ISO)

• IANA registers port 13400 for DoIP: TCP for diagnostic data, UDP for vehicle discovery.
• ISO 13400-2 covers IP address assignment, vehicle announcement and discovery, routing to the vehicle's ECUs and, optionally, TLS.
• ISO 13400-3:2016 uses an IEEE 802.3 100BASE-TX physical layer; ISO 13400-4:2016 adds Ethernet to the ISO 15031-3 (J1962) connector with two pin-assignment options.
• UDS over IP is ISO 14229-5.

Sources [11, 47]

ISO 9141:1989; ISO 14230-1:2012

• ISO 14230-2:2016 describes a UART-based data link on the K-line and explains how ISO 9141 and ISO 14230 initialisation differ.
• On the J1962 connector the K-line is pin 7 and the L-line pin 15; ELM notes many vehicles do not need the L-line for initialisation, but some do.
• UDS can run on K-line (ISO 14229-6).

Sources [10, 11]

ISO 11898-1:2024; Bosch CAN 2.0 (1991)

• 11-bit base-frame identifiers (Bosch CAN 2.0 Part A) or, with Part B, also 29-bit extended identifiers; 0 to 8 data bytes; the lowest identifier wins arbitration.
• Since 2003 all CAN CC implementations must handle both frame formats.
• CiA: at 1 Mbit/s 40 m is the theoretical limit and real networks reach less; lower bit rates allow longer cables, but beyond about 1 km voltage drop needs thicker cable.
• CiA's rule of thumb: keep average bus load at or below 50 percent.

Sources [11, 29, 30, 32, 39]

ISO 11898-2:2026 (ISO)

• Recessive: CAN_H and CAN_L both nominally 2.5 V. Dominant: CAN_H about 3.5 V and CAN_L about 1.5 V. A dominant differential of 0.9 to 2.0 V and a recessive differential of -1.0 to 0.5 V are valid.
• Terminate a line topology with 120 ohm at both ends (sometimes split 2 x 60 ohm with a capacitor to ground). Two 120 ohm resistors in parallel measure 60 ohm between CAN_H and CAN_L with the bus unpowered.
• Low-power (formerly ISO 11898-5) and selective wake-up (formerly ISO 11898-6) transceivers were merged into ISO 11898-2; ISO lists 11898-5 and -6 as withdrawn.

Sources [11, 30]

ISO 11898-3:2006 (ISO)

• CiA: no longer recommended for new designs; new designs use high-speed transceivers with low-power modes instead.

Sources [11, 31, 32]

SAE J2411:2000 (SAE)

• Defines the physical layer and part of the data link for CSMA/CR data links on a single wire.
• CiA: no longer recommended for new designs.

Sources [15, 31]

ISO 11898-1:2024 (ISO); CiA 601

• Up to 64 data bytes per frame, and the data phase can run faster than the 1 Mbit/s arbitration phase. With a 1:8 bit-rate ratio CiA estimates about six times the throughput of CAN CC.
• No remote frames. Stronger CRC (17- or 21-bit plus a stuff-bit counter).
• Data-phase limits depend on the transceivers and topology. CiA's two pages disagree on signal-improvement (SIC) transceivers: one says up to 8 Mbit/s in hybrid topologies, the other that the SIC option limits the data phase to 5 Mbit/s.
• SAE J1939-22 maps J1939 onto CAN FD.

Sources [31, 32, 33, 36]

ISO 11898-1:2024 (ISO); CiA 610

• 1 to 2048 data bytes; an 11-bit priority ID plus a 32-bit acceptance field; up to 256 virtual networks (VCID) on one cable.
• CAN SIC XL transceivers in FAST mode use PWM coding to reach 20 Mbit/s or more, depending on network design.
• CiA (network-design page): CAN XL parts are still mostly in prototype volumes.

Sources [11, 31, 32, 34]

ISO 17987:2016-2025; LIN 2.2A (2010)

• Bytes are sent UART-style with one start bit and one stop bit and no parity; one bit at 19.2 kbit/s lasts 52 microseconds.
• LIN 2.2A: a cluster should not exceed 16 nodes (each extra node lowers network resistance by about 3 percent) and the bus length is at most 40 m.
• SAE J2602 is the SAE recommended practice for LIN; UDS on LIN is ISO 14229-7.

Sources [11, 40, 41]

ISO 17458-1 to -5:2013 (ISO)

• ISO 17458-4 specifies the electrical physical layer for time-triggered networks at up to 10 Mbit/s over dual wires.
• Diagnostic transport on FlexRay is ISO 10681; UDS on FlexRay is ISO 14229-4.

Sources [11]

ISO 21806-1 to -14 (2020-2021)

• ISO 21806 specifies a 150 Mbit/s optical physical layer (part 8), a 150 Mbit/s coaxial physical layer (part 10) and a 50 Mbit/s balanced-media physical layer (part 12).
• MOST25 is not one of the ISO 21806 parts; its figures are not given here because no downloadable source was found.

Sources [11]

IEEE 802.3bw-2015 (IEEE)

• Task-force objectives: 100 Mbit/s over a single balanced twisted pair in automotive conditions, at least 15 m, full duplex only, bit-error ratio 10^-10 or better.
• Approved by the IEEE-SA Standards Board in October 2015.

Sources [42]

IEEE 802.3bp-2016 (IEEE)

• Objectives: point-to-point over one twisted pair with up to four inline connectors for at least 15 m in vehicles, and a goal of at least 40 m for industrial, aircraft, rail, bus and heavy-truck links.
• Approved 30 June 2016.

Sources [43]

IEEE 802.3cg-2019 (IEEE)

• Objectives: a 15 m point-to-point link, a 25 m mixing (multidrop) segment with at least 8 nodes, and a 1 km point-to-point link with up to 10 inline connectors; optional power over the same pair.
• ODVA notes that Ethernet-APL for process instruments is built on 10BASE-T1L from IEEE 802.3cg-2019.

Sources [44, 61]

SAE J1939 family (SAE)

• J1939-21 uses only the classical extended frame format (29-bit identifiers); no other data link layer is permitted.
• Physical layers: J1939-11 (250 kbit/s, shielded twisted pair), J1939-15 (250 kbit/s, unshielded), J1939-14 (500 kbit/s). CAN FD controllers on -11 or -14 networks must be restricted to classical frames; J1939-22 is the CAN FD mapping.
• Intended for light, medium and heavy-duty vehicles on and off road, their trailers, construction and agricultural equipment, and stationary uses such as generator sets.

Sources [2, 16, 17, 18, 19, 36]

SAE J1939-73:2022 (SAE)

• Defines the diagnostic messages (DMs): broadcasting active DTCs, lamp status, reading and clearing DTCs, memory access and security.
• DM1, the active-fault list, is the only DM broadcast continually; the ELM327 datasheet shows it arriving at one-second intervals.

Sources [10, 21]

SAE J1939-71:2022; J1939DA

• SAE: the parameters (SPs) and messages (PGs) that used to be published in J1939-71 are now published in the J1939DA digital annex; J1939-71 keeps the conventions.

Sources [2, 20]

SAE J1939-13:2024 (SAE)

• Connectors for the J1939-11, J1939-15 and J1939-14 media and for ISO 11783-2 (ISOBUS) quad cable.
• Required for US heavy-duty OBD when the J1939 protocol is used (40 CFR 86.010-18(k)(2)).

Sources [5, 22]

SAE J1939-81; J1939-84 (SAE)

• J1939-81 is 'Network Management' and J1939-84 'OBD Communications Compliance Test Cases for Heavy Duty Components and Vehicles' (titles as listed in 13 CCR 1971.1).

Sources [2]

SAE J1708 (stabilized 2016)

• Defines the serial link's hardware and basic protocol between microcomputer modules in heavy-duty vehicles; the data carried is defined in separate application documents.
• Its bit rate and node limits are not shown because no downloadable source was found.

Sources [23]

SAE J1587 (stabilized 2013)

• Defines message formats and data (field size, scale, position, transmit frequency) for modules on a heavy-duty data link; SAE lists J1708 as a related document.

Sources [24]

SAE J1922 (stabilized 2011)

• An interim engine/transmission/ABS/retarder control protocol 'until higher speed communication links are established'.

Sources [25]

ISO 11783 parts 1-14 (ISO)

• ISO 11783-2: 250 kbit/s on twisted non-shielded quad cable, or the backward-compatible twisted-pair physical layer (TPPL).
• ISO 11783-3:2026 maps messages to 29-bit CAN frames and uses J1939-21-based transport. Other parts: -5 network management, -7 implement messages, -10 task controller, -12 diagnostics, -13 file server, -14 sequence control.
• The AEF publishes guidelines that narrow the standard's options so ISOBUS products work together.

Sources [11, 65]

ISO 11992-1 to -4 (ISO)

• For towing and towed vehicles over 3500 kg; part 2 is a J1939-based application layer for braking and running gear, part 4 diagnostics.
• CiA: the 125 kbit/s truck/trailer transceiver is required by European regulations; its physical layer is not compatible with J1939 or ISO 11783.

Sources [11, 31, 38]

SAE J2497 (SAE)

• Bidirectional serial link over the vehicle power supply line between tractor and trailer modules; includes activating the trailer ABS indicator lamp in the tractor.
• SAE's 2024 work item adds attack vectors and mitigations, because research showed J2497 receivers can pick up remote RF-induced signals.

Sources [26]

NMEA 2000 v3.000 (NMEA); IEC 61162-3

• Multi-master, self-configuring network with no central controller; products must be NMEA-certified.
• Elm Electronics: NMEA 2000 uses 250 kbit/s and a data format almost identical to J1939, so a J1939-capable interface can listen to it.

Sources [10, 36, 64]

CiA 301; EN 50325-4; EN 50325-5

• CiA 301 bit timing covers 10 to 1000 kbit/s; predefined identifiers are 11-bit, but 29-bit is supported.
• Each device has an object dictionary: 1000h-1FFFh communication parameters, 2000h-5FFFh manufacturer-specific, 6000h-9FFFh standardised profile parameters.
• CANopen Safety (CiA 304) became EN 50325-5 in 2009; CANopen FD is CiA 1301.

Sources [35, 36, 38]

IEC 62026-3; ODVA

• Thick-trunk lengths: 500 m at 125 kbit/s, 250 m at 250 kbit/s, 100 m at 500 kbit/s; trunk-line/drop-line topology.
• Only CAN CC frames are allowed, and no remote frames.

Sources [37]

MIL-STD-1553C (US DoD, 2018)

• Manchester II bi-phase coding at 1.0 Mbit/s plus or minus 0.1 percent.
• 20-bit words: 3-bit-time sync, 16 bits, odd parity. Remote terminals take any unique address from 0 to 30.

Sources [58]

ISO 15118-2:2014, -3:2015, -20:2022

• Part 2: messages and data model with XML/EXI, V2GTP, TLS, TCP and IPv6. Part 3: physical and data link layer for wired high-level communication. Part 20: second-generation messages including bidirectional power transfer.
• US NEVI-funded chargers must conform to ISO 15118-3, have hardware for 15118-2 and 15118-20, and support Plug and Charge (23 CFR 680.108); charger-to-network links use OCPP (2.0.1 from 28 February 2024).

Sources [7, 11]

IEC 61851-1:2017 (IEC)

• Applies to EV supply equipment up to 1000 V AC or 1500 V DC; covers the equipment's characteristics, the connection to the vehicle and electrical safety. ISO 15118-3 builds on its basic signalling.

Sources [11, 66]

SAE J1772:2024 (SAE)

• Physical, electrical, functional and performance requirements for conductive charging in North America.
• The CCS1 inlet (J1772 combo) adds two DC pins below the J1772 connector (US DOE AFDC). NEVI Level 2 ports must have a J1772 connector and DC ports a CCS Type 1 connector.

Sources [7, 27, 67]

SAE J3400:2024 (SAE)

• Covers AC single-phase or DC power through two current-carrying contacts; the 2024 revision added communication requirements and reference devices.
• US DOE: SAE standardised J3400 from Tesla's NACS design.

Sources [28, 67]

CHAdeMO Association

• 23 CFR 680.104 defines CHAdeMO as a protocol for a DC fast-charging connector interface that specifies physical, electrical and communication requirements. NEVI allows CHAdeMO connectors only with FY2022 funds.

Sources [7, 67]

Modbus over Serial Line V1.02 (Modbus.org)

• One master and up to 247 slaves (addresses 1-247; 0 is broadcast). 19200 bit/s is the required default; even parity is the default and no parity needs 2 stop bits.
• 32 devices are always allowed on an RS-485 segment without a repeater. With AWG 26 or thicker cable at up to 9600 bit/s the trunk can be 1000 m; drops at most 20 m.
• Terminate each end with 150 ohm, or 120 ohm in series with 1 nF when the line is polarised.

Sources [48]

Modbus Messaging on TCP/IP V1.0b

• Servers listen on TCP port 502 by default (Modbus.org; IANA registers 502 as the Modbus Application Protocol). IANA registers port 802 for Modbus Application Protocol Secure.

Sources [47, 49]

TIA-232 (TIA)

• TI: line length is limited by the 2500 pF maximum capacitive load, which gives about 20 m; drivers swing plus or minus 5 to 15 V.

Sources [51]

TIA/EIA-422 (TIA)

• One driver to as many as ten receivers; terminated only at the far end; receivers detect 200 mV differential.

Sources [51]

TIA/EIA-485 (TIA)

• TI: drivers must drive 32 unit loads; 1/8-unit-load transceivers allow up to 256 nodes. Daisy-chain topology, 120 ohm cable terminated with 120 ohm at both ends.
• TI's figures: 10 Mbit/s at 40 ft (12 m) and 4000 ft (1200 m) at 100 kbit/s; its rule of thumb keeps length (m) times rate (bit/s) under 10^7.

Sources [50]

IEC 61158; PI

• Up to 126 I/O devices on a PROFIBUS DP cable. PROFIBUS PA uses MBP (Manchester-coded, bus-powered) transmission with a typical 10-15 mA per device from the bus.

Sources [59]

PI; IEC 61158

• PROFINET specification V2.3 adds fast forwarding, dynamic frame packing and fragmentation for cycle times down to 31.25 microseconds.
• IANA ports registered to PI: 34962 (RT unicast), 34963 (RT multicast), 34964 (context manager).

Sources [47, 60]

ODVA (CIP)

• Uses IEEE 802.3 Ethernet, TCP/IP for messaging and UDP for time-critical I/O; up to 1500 data bytes per frame.
• IANA ports: 44818 (EtherNet/IP messaging) and 2222 (EtherNet/IP I/O).

Sources [47, 61]

ANSI/ASHRAE 135-2024; ISO 16484-5

• First published as ANSI/ASHRAE Standard 135 in 1995 and as ISO 16484-5 in 2004; maintained by ASHRAE SSPC 135.
• Runs over IPv4/IPv6 or on MS/TP twisted pair; IANA registers port 47808 for BACnet.

Sources [47, 62]

ANSI E1.11-2024 (ESTA)

• ESTA's ANSI E1.11 (USITT DMX512-A) is the update of DMX512/1990 for controlling dimmers, colour changers and related equipment. Its electrical figures are not shown: ESTA's free download requires registration and no other downloadable source was found.

Sources [63]

No single standard

• Each byte is framed by a start bit and stop bit(s), with optional parity. Modbus RTU, for example, uses 11 bits: 1 start, 8 data (LSB first), 1 parity, 1 stop; LIN uses 1 start, 8 data and 1 stop with no parity.
• Rates in the Modbus serial spec: 9600 and 19200 required, others such as 1200 to 115200 optional; each rate must be within 1 percent when sending and tolerate a 2 percent error when receiving.

Sources [40, 48]

NXP UM10204 Rev. 7.0 (2021)

• Standard-mode 100 kbit/s, Fast-mode 400 kbit/s, Fast-mode Plus 1 Mbit/s, High-speed mode 3.4 Mbit/s; Ultra Fast-mode is unidirectional at up to 5 Mbit/s.
• 7-bit addressing is mandatory and 10-bit optional. The device count is limited only by bus capacitance: 400 pF in Standard and Fast mode, 550 pF in Fast-mode Plus.

Sources [53]

SMBus 3.3 (SMIF, 2024)

• Unlike I2C, SMBus has a minimum clock of 10 kHz and a clock-low timeout: if the clock is held low for longer than 25 ms (tTIMEOUT,MIN) devices may conclude a device is faulty, and must reset their communication by 35 ms (tTIMEOUT,MAX).

Sources [53, 54]

PMBus Part I Rev. 1.3 (SMIF, 2014)

• Published by the System Management Interface Forum, which also publishes SMBus; NXP's I2C manual lists PMBus among the architectures built on I2C.

Sources [53, 54]

Vendor-defined (e.g. TI SPRUGP2A)

• TI's KeyStone SPI guide describes 3-pin operation and 4-pin operation with a chip-select line per peripheral; the maximum clock is set by each device's datasheet.

Sources [52]

Analog Devices (Maxim) app notes

• Every device has a factory 64-bit ID that includes an 8-bit family code.
• AN126 recommended master timing: a standard-speed write slot of 70 us (6 + 64 or 60 + 10 us) and an overdrive slot of 8.5 to 10 us; reset pulse 480 us (70 us overdrive).
• AN148: radius and weight (total cable) up to 200 m with a slew-controlled FET driver and 1 kohm pull-up, up to 500 m with an active-pull-up master.

Sources [55, 56, 57]

IEEE 1149.1-2013 (IEEE)

• The mandatory terminals are TDI, TDO, TMS and TCK; TRST is optional (Arm ADIv5).
• IEEE SA lists IEEE 1149.1-2013 as an inactive-reserved standard since 21 March 2024.

Sources [45, 46]

Arm ADIv5 (IHI 0031)

• One bidirectional data pin (SWDIO) and a clock (SWCLK): two pins instead of JTAG's usual four. An SWJ-DP port can switch between JTAG and SWD.

Sources [46]