Users Manual Part 4

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CAN Bus
A Controller Area Network (CAN bus) is a robust vehicle bus standard designed to
allow microcontrollers and devices to communicate with each other in applications
without a host computer.
SAE International
Initially established as the Society of Automotive Engineers, is a U.S.-based, globally
active professional association and standards developing organization for engineering
professionals in various industries. Principal emphasis is placed on transport industries
such as automotive, aerospace, and commercial vehicles.
SAE J1708
SAE J1708 is a standard used for serial communications between ECUs on a heavy
duty vehicle and also between a computer and the vehicle. With respect to Open
System Interconnection model (OSI), J1708 defines the physical layer. Common higher
layer protocols that operate on top of J1708 are SAE J1587 and SAE J1922. The
protocol is maintained by SAE International.
SAE J1939
Society of Automotive Engineers standard SAE J1939 is the vehicle bus recommended
practice used for communication and diagnostics among vehicle components. It is used
in the commercial vehicle area for communication throughout the vehicle, with the
physical layer defined in ISO 11898.
J1850
Defines a serial data protocol. There are two variants- 10.4 Kbit/s (single wire, VPW)
and 41.6 Kbit/s (two wire, PWM). Mainly used by US manufacturers, also known as PCI
(Chrysler, 10.4 Kbit/s), Class 2 (GM, 10.4 Kbit/s), and SCP (Ford, 41.6 Kbit/s).
OBD
On-board diagnostics (OBD) is an automotive term referring to a vehicle's
self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair
technician access to the status of the various vehicle subsystems.
OBD-II diagnostic connector
The OBD-II DLC (post-1996 vehicles) is usually located under the instrument panel on
the driver side, though there are several exceptions. The SAE J1962 specification
provides for two standardized hardware interfaces, called type A and type B. Both are