AT commands

A command language supported by the ELM327 with “AT” meaning “attention.”


Name of the Nissan Leaf CAN bus which carries predominantly infotainment data. Exposed on pins 3 and 11 of the diagnostic connector.


Abbreviation for controller area network.

CAN protocol

Transport protocol (layer 4) and network (layer 3) protocol implemented on a CAN bus. The OBD-II protocol used by the Nissan Leaf is ISO 15765-4 CAN (11-bit ID, 500 kBd).


Name of the Nissan Leaf CAN bus exposed on pins 6 and 14 of the diagnostic connector.

communication protocol

A system of rules that allow two or more entities of a communications system to transmit information.

controller area network

A vehicle bus standard designed to allow microcontrollers and devices to communicate without a host computer.

diagnostic connector

A physical connector used to access on-board diagnostics and data streams. The OBD-II diagnostic connector (defined in ISO 15031-3) is a 16-pin connector which, on a Nissan Leaf, is located beneath the steering column.

diagnostic tool

An electronic device that interfaces with a vehicle’s diagnostic connector.


A proprietary, pre-programmed, microcontroller produced by ELM Electronics Inc.[1] for communicating with a vehicle’s on-board diagnostics interface. The ELM327 command protocol is one of the most popular PC-to-OBD interface standards and is also implemented by other vendors.

ELM327 compatible

Used to describe a device capable of translating the on-board diagnostics interface and which supports the ELM327 command set.


Name of the Nissan Leaf CAN bus which carries data related to the traction battery and electric motor drive system. Exposed on pins 12 and 13 of the diagnostic connector.


Unit named after Gary Giddings who is credited with discovering the significance of 5B3 SoH, GID byte F.

ISO 15031-3

Document published by the International Organization for Standardization[2] (ISO) titled Road vehicles — Communication between vehicle and external equipment for emissions-related diagnostics — Part 3: Diagnostic connector and related electrical circuits: Specification and use.

ISO 15765-4

Document published by the International Organization for Standardization[2] (ISO) titled Road vehicles — Diagnostic communication over Controller Area Network (DoCAN) — Part 4: Requirements for emissions-related systems.


Abbreviation for kilobaud where 1 kBd = 1000 Bd (baud).


Abbreviation for revision two of the on-board diagnostics standardised interface.

on-board diagnostics

A term referring to a vehicle’s self-diagnostic and reporting capability.

parameter ID

A hexadecimal code used to identify data on a CAN bus.


Abbreviation for parameter ID.

SAE J1962

Document published by SAE International[3] titled Diagnostic Connector Equivalent to ISO/DIS 15031-3:December 14, 2001. This document specifies the functional requirements for the physical OBD-II diagnostic connector. The equivalent international standard is ISO 15031-3.


State of Heath. Measure of the ability of a battery to store and deliver electrical energy relative to a new battery.

terminal application

Application that sends and receives text data over a serial interface.

Type A diagnostic connector

A diagnostic connector defined in Figure A.1 of ISO 15031-3.