Is J1708 RS485?

J1708 Half-Duplex Collision Detection SAE J1708 is basically an RS485 hardware interface without the typical 120 ohm termination resistors. In typical applications, a half-duplex RS485 transceiver chip is used to connect to the bus.

What is code J1708?

Society of Automotive Engineers standard 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.

What is the maximum data speed of a J1708 1587 data link?

Data on the J1708 moves at 9600 bits per second, which is much slower than today’s modern J1939 network. There can also be a maximum of 20 ECMs, or “nodes”, on the J1708 network.

When was J1708 introduced?

The SAE J1708 specification was defined by the SAE and TMC in 1986. Its main purpose is to address the transmission of electronic signals and information among truck and bus components (i.e. Electronic Control Units or ECUs). J1708 is mainly used on heavy-duty and commercial vehicles.

CAN SAE J1939?

J1939 is a higher-layer protocol based on Controller Area Network (CAN). It provides serial data communications between microprocessor systems (also called Electronic Control Units – ECU) in any kind of heavy-duty vehicles.

What is a J1939 connector?

The SAE J1939/13 Standard defines a standard connector for diagnostic purpose. It does allow access to the vehicle communication links. The connector is a Deutsch HD10 – 9 – 1939 (9 pins, round connector).

What is SAE J1979?

SAE J1979/ISO 15031-5 set includes the communication between the vehicle’s OBD systems and test equipment implemented across vehicles within the scope of the legislated emissions-related OBD.

What does SPN and FMI stand for?

Suspect Parameter Number (SPN) Represents the SPN with error. Every defined SPN can be used in a DTC. Failure Mode Identifier (FMI) Represents the nature and type of error that occurred, e.g., value range violation (high or low), sensor short-circuits, incorrect update rate, calibration error.

What is the sample rate for J1587 data link?

The J1587/1708 data link consists of a pair of 18 gauge twisted wires. The nominal rate of twist required is 1 twist per 25.4 mm (1 inch) or 40 twists per meter (3.28 feet). This twist helps protect against electrical interference.

What is SAE J1939 protocol?

What is SAE J1939 standard?

J1939 is a set of standards defined by SAE (there’s an overview here). They are used in heavy-duty vehicles such as trucks and buses, mobile hydraulics, etc. In many ways, J1939 is similar to the older J1708 and J1587 standards, but J1939 is built on CAN.

Is J1939 the same as NMEA 2000?

J1939 and NMEA 2000 networks are both based on the same hardware (Controller Area Network (CAN)), and both protocols use the same message format (the messages are actually compatible and can coexist on the same network), however, NMEA uses different messages from J1939 for most parameters.