T3.1: Identify characteristics of the J1939 Protocol.

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Update

J1939 is a communication protocol layered over CAN that extends its functionality. It is commonly used in large vehicles like tractors and trucks. J1939 utilizes an extended 29-bit CAN identifier.

Within the CAN ID, there is a Parameter Group Number (PGN) that specifies the type of data the CAN frame contains. Within the CAN data field, Suspect Parameter Numbers (SPNs) define the exact data being transmitted. Other than these two components, the CAN frame structure remains unchanged.

J1939 also includes specific PGNs that enable the Transport Protocol (TP), which supports both Peer-to-Peer and Broadcast communication. This allows transmitting more than 8 bytes of data across multiple CAN frames.

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Standard CAN Frame

J1939 CAN Frame