High-performance SAE J software based protocol stack. Complete J source code is provided. Get on the Bus: J and J Vehicle Bus Standards on established protocols that vary based on vehicle manufacturer, vehicle model. J defines the physical layer, which are the hardware (wiring) and basic protocol that is needed for J and J to transmit messages.

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J / J Network Operation and Testing – BusTekHub

This means that all the transmitting onto the J bus requires a logic inverter. If this were not done properly, then the receiver would flag it as an error. J is a multi-master network tooand it implemented the bus arbitration too, but different than the CAN hardware arbitration, J using softrware. The CAN protocol is totally incompatible with J SAE J and J are different on software and hardware.

J is outdated and is currently being phased out of production.

Get on the Bus: J1708 and J1939 Vehicle Bus Standards

The original standard is recognized by two designators: Haven’t received registration validation E-mail? It still has power, ground and J connections in addition to the new J wires. The hardware utilized are RS transceivers wired for open collector operation through the use of a pullup rpotocol pulldown of the separate data lines. Thanks to all for your reply. Interfaces are listed by their speed in the roughly ascending order, so the interface at the end of each section should be the fastest.


A RS transceiver connected in passive mode is used as the bus prktocol.

The only indication of when the message is over is when the transmission stops. It uses 8, N, 1 byte framing and has a network speed of bits per second bps.

The max length of any J is 21 bytes 10 bits per character.

J and J Vehicle Bus Standards | Omnitracs

J Checksum The last byte of every message is the two’s complement of the MID and data contained in the message. Hi The Can controller area network on this j708 is not a very successful topic I have also questions on this forum about Can It is just strange that not one of the microchip application Engineers get involved in this topic.

It defines the physical layer and data link layer. The maximum length, from the MID to the checksum, is 21 bytes.

j1708 and CAN

Its main purpose is to address the transmission of electronic signals and information among truck and bus components i. Automotive standards Technology stubs. If you have any questions, please contact us at http: However, there are still something similiar: The protocol is maintained by SAE International.


The basic problem is that the CAN specification defines certain requirements around the identifier, or the first part of prtoocol message. Now that I know more. I have the same feeling about this forum, “no moderaters involved” there are so many questions about CAN.

J — the physical layer i. Opinions expressed in the content posted here are the personal opinions of the original authors, and do not necessarily reflect those of Omnitracs, LLC or its subsidiaries “Omnitracs”. The first byte of every message is the MID, which stands for message identifier.

There are 8 different priorities, ranging from 1 to 8. Common application and transport layers used on J are J and J Each subsequent priority adds an additional 0.

Links to useful PIC information: This includes bit stuffing at pre-defined intervals the transmitter adding bits that are not part of the message at all. If this time is exceeded, the message is not valid.