J1939 Transmit

J1939 Transmit (not recommended)


Simulink® Real-Time™ Library of Drivers No Longer Recommended for Use


The J1939 Receive block sends the PGNs.

Block Inputs

The J1939 Transmit block inputs are typically connected directly to one or more J1939 Pack blocks. The output of the J1939 Transmit block is typically connected to the input of a CAN FIFO Send block. The J1939 Transmit block input is of type unsigned 8-bit integer. The bytes are:

Data Page and Reserved Bits
PDU Format
PDU Specific
Destination Address
Data Frame Size [0]
Data Frame Size [1]
New message Flag

Block Outputs

The J1939 Transmit block has a single output port of type double. The output signal is a matrix of size n x 6, where n is the value in the Number of input messages parameter. At this port, you must provide information required to construct valid CAN messages to be written into the transmit FIFO. For each CAN message, you must pass six elements. See the documentation for the FIFO Write block (such as Softing CAN-AC2-PCI with Philips SJA1000 FIFO Write) for a detailed description of these elements.


The value can be either 1 (port 1) or 2 (port 2) and defines the port the CAN message is sent from.


Identifier of the CAN message to be sent. If it is a standard CAN message, the valid range is 0 to 2047. If the CAN message is extended, the range is 0 to 229-1. J1939 identifiers are extended. J1939 messages can share the physical network with another protocol using standard identifiers.

Identifier type

The value can be either 0 (standard identifier range) or 1 (extended identifier range) and defines the identifier type of the outgoing CAN message. J1939 identifiers are extended.

Data frame size

The value can be in the range of 0 to 8 and defines the data frame size of the outgoing CAN message in bytes. The CAN messages generated by J1939 are usually 8 bytes in length. The exception is the request message, which has a length of 3 bytes.


This is the data for the data frame itself and is defined as a double value (8 bytes). The CAN packing block is used to construct the data as a double value.

Block Parameters

Port (1 or 2)

Enter the port from which to send the message. Enter a value of 1 (port 1) or 2 (port 2) to define the port the CAN message is sent from.

Number of input messages

Specify the number of inputs to this block. One input for each unique PGN and destination address is required.

Source Address

Specify the source address for the messages of the current node.

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