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.
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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.
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).
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.
