SAE J1939 communication is a in-vehicle networking protocol for ensuring seamless interaction between ECUs in heavy-duty vehicles. Understanding the different types of SAE J1939 communication is crucial for optimizing vehicle performance and diagnostics. There are three types of communication in J1939: Peer-to-peer, Broadcast and Proprietary.
Table of Contents
Destination specific (peer-to-peer) Communication
Messages are sent to a specific ECU in this type of SAE J1939 communication. It uses PDU1 (PDU Format values 0 to 239). A Destination address is required.
![Types of SAE J1939 communication - Destination Specific (peer-to-peer)](https://automotivevehicletesting.com/wp-content/uploads/2024/07/SAEJ1939-Destination-Specific-Communication.png)
Broadcast Communication
Broadcast messages are sent to all the ECUs in the network. This is used when messages are need to be broadcast to a larger audience. It uses PDU2 (PDU Format values 240 to 255)..
NOTE: PDU Format is the most significant byte of the PGN. The least significant byte is considered to be zero. Example: If the PDU Format = 0xEA, then PGN is 0xEA00 (59904 decimal).
![Types of SAE J1939 communication - Broadcast](https://automotivevehicletesting.com/wp-content/uploads/2024/07/SAEJ1939-Broadcast-Communication.png)
Proprietary Communication
Proprietary communication uses either PDU1 or PDU2 and It can be either Destination specific or broadcast. Proprietary PGNs are used in this type of communication.
NOTE: PGN = 18 bits + 6 zero bits= 24 bits (3 bytes) [Add 6 zero bits to the extreme left].
These are the three different types of message communication in SAE J1939 protocol.