A set of python scripts to work with SAE J1708 protocol over serial port communication.

SAE J1708 protocol is used in various heavy-duty equipment (e.g., lorries, loaders, diggers, etc.) and is a simple communication protocol supporting CRC shechsum. Detailed description of the protocol is provided here.

A J1708 message example:

The first byte in every message must always be a MID. Valid values of the MID is 0-255.

• MIDs 0-68 belong to predefined devices to ensure consistency.
• MIDs 69-86 are set aside for J1922 protocol.
• MIDs 87-110 are reserved for future applications. Manufactures may apply to SAE Truck and Bus Electrical Committee to define a MID. MID 111 is designated for factory tests of electronic control units and shall not be used by any on-board unit.
• MIDs 112-127 are not reserved and can be used as wanted. MIDs 128-255 are reserved for the SAE J1587 protocol, where they are defined.

The checksum is calculated as following:

As an example (using the sample message in the figure above),

• 44+23+61+114+62+208 = 512
• (512 AND 0xFF) = 0, so the message is correct.

The scripts have a number of dependencies that can be installed using

To use the scripts the following packages are required:

• pyserial
• time
• csv
• sys
• signal
• os

To install the above-mentioned packages use the following commands:

python -m pip install --upgrade pip
python -m pip install serial, time, csv, sys, signal, os

To read the serial bus COM-port number has to be updated in line 46 in j1708_com_receive.py. It is also advisible to check com.baudrate and com.timeout

Running of the script from CLI by:

python j1708_com_receive.py

will result in a log file to be created in logs/ folder.