m a x A I 4 3 0 & m a x A I 4 3 0 v T E C H N I C A L M A N U A L
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Rev A 8/24/2020
4.3 Data-Bus Communication Protocol Basics
SAE J1939 data-bus devices transmit data to and/or receive data from the bus. Data is broken down into
a structured format, designated specifically by the SAE standard, containing a Source Address (SA), a
Parameter Group Number (PGN), and parameter data.
The source address is the number at the beginning of the data packet that identifies where the data was
transmitted from. For example, SA 0 indicates that the data packet was transmitted from the primary
engine controller.
The parameter group number is the identification label for the group of data that follows the PGN. This
defines what type of information the parameter data will be (e.g. engine oil pressure values).
The parameter data is a group of data bytes that contain the specific values of the particular PGNs
parameters (e.g. engine oil pressure). When a device
listening
to the data-bus
hears
the appropriate SA and
PGN, it then reads the desired data to complete the data transmission.