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SAE J1939 Programming with Arduino – RTS/CTS Session Test Program

Posted by Wilfried Voss on

This post is part of a series about SAE J1939 ECU Programming & Vehicle Bus Simulation with Arduino.

SAE J1939 ECU Programming & Vehicle Bus Simulation with Arduino

Just for kicks, I extended the previously used Arduino sketch to simulate a fully functional RTS/CTS session (yet again, the code is highly tailored to the previous RTS/CTS session). 

Based on that sketch, I could simulate all error scenarios on the receiver’s side.

This screen shot shows the complete RTS/CTS session with the Arduino Uno sketch acting as the simulated communication partner.

Without explaining every single line (that has been done before), the complete RTS/CTS session took place according to SAE J1939/81.

The modified code is as follows (see highlighted sections):

Global memory space:

loop() function:

Note: As always, this software project is available through the download page at

A Comprehensible Guide to J1939

SAE J1939 has become the accepted industry standard and the vehicle network technology of choice for off-highway machines in applications such as construction, material handling, and forestry machines. 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. The messages exchanged between these units can be data such as vehicle road speed, torque control message from the transmission to the engine, oil temperature, and many more.

A Comprehensible Guide to J1939 is the first work on J1939 besides the SAE J1939 standards collection. It provides profound information on the J1939 message format and network management combined with a high level of readability.