A Parameter Group (PG) in J1939 is the same concept as a CAN frame.
PG is the exchange of information from ECUs to ECUs in a J1939 protocol network. PG is a set of signals that has similar transmission range and content definitions.
A group of parameters can be transmitted in 2 ways.
- In a single instance when its size = that 8 bytes.
- In different instances (of 8 bytes) distributed when the size is> 8 bytes.
In the case of parameter groups> 8 bytes, the transport protocol layer is used to communicate ECUs between them.
PDU-1 type Parameter Group
PDU-1 Parameter Group will contain an address of the sending node and an address of the receiving node. A receiving node can only receive a Parameter Group, if such a Parameter Group contains the address of such a receiving node.
Each node has a “one” on “one” communication because the source and destination address are specified.
When there are two nodes with the same target address, the source address is ignored, but the destination address is not ignored. In this way, the receiving node can receive the 2 groups of parameters.
When receiving nodes have the same source address, then the Parameter Group to be transmitted is duplicated and sent independently to each node.
PDU-2 type Parameter Group
When a Parameter Group is specified for broadcast communication, then it is defined as PDU-2 format and will only contain the address of the sending node and can be received by all receiving nodes.
Parameter Group can be discriminated when defining a destination address, even when the PGN is the same:
When broadcasting parameter groups, a destination address is not defined and thus, all nodes will receive the parameter group. The only exception is when a receiving node specifies a source address, then this node can only receive data from the specified source address.