SAE J1939

SAE J1939 is a CANbus protocol that is supported by Enhanced Division Vision OPLC™ models. Within the J1939 network, the Vision functions as an ECU (Electronic Control Unit). Note that Vision supports transport protocols such as BAM and RTS/CTS.

Depending on the Vision model, the CANbus port may be an integral part of the PLC, or may be purchased and installed separately.

Configuring J1939

The J1939 Configuration has three tabs comprising the parameters listed below. Note that the Status parameter, J1939 Configuration Startup process status, provides status messages for all tabs in the Configuration.

J1939 Protocol Errors

Byte 1 (MSB)
0	No error
FF	Error exists

Byte 2: Error Location
0	Error unit
1	Data link layer unit
2	Transport unit
3	Networking unit
4	Application unit
5	Cyclic unit
6	Memory unit

Byte 3: The Error Classes (Priorities)
0	Warning, Application OK
1	Error occurred
2	Fatal Error

Byte 4: The error for each unit
Data link layer unit	Synchronous Errors	1	overrun in the Tx Queue
		2	starting CAN failed
		3	reset CAN failed
		4	init CAN failed
	Asynchronous Errors	11	bus error interrupt occurs on CAN
		12	error warning interrupt occurs on CAN
		13	CAN controller is in status error active
		14	data overrun interrupt occurs on CAN
		15	overrun in the Rx Queue
Transport unit	Synchronous Errors	1	No free Entry in the Tx Queue of the TPL available
	Synchronous Errors	2	Too many PGNs tried to register in the config filter
	Asynchronous Errors	11	Unexpected BAM frame received
		12	Unexpected RTS frame received
		13	Unexpected CTS frame received
		14	Unexpected EOM frame received
		15	Unexpected CA frame received
		16	Unexpected DT frame received
		17	No free Rx Msg Buffer in the TPL for a global message available
		18	Timer overrun for Tx Timeout T0
		19	Timer overrun for Tx Timeout T1
		20	Timer overrun for Tx Timeout T2
		21	Timer overrun for Rx Timeout T0
		22	Timer overrun for Rx Timeout T1
		23	Timer overrun for Rx Timeout T2
		24	The length of the received message is too long for a segmented message
		25	Error by Sending: Can't send a segmented message
		26	Sending a CA message failed
		27	Sending a NACK message failed
Networking unit	Asynchronous Errors	11	The device can't claim a free address
Networking unit	Asynchronous Errors	12	The address list is full
Application unit	Synchronous Errors	1	APL_Main() was not called in the required sequence
		2	The data field is too long (could not sent message)
		3	No memory for the data field allocated
		4	An error occurred during registration of a request PGN
	Asynchronous Errors	11	A request message couldn't be answered from the request handler because there was no place in the queue
Cyclic unit	Synchronous Errors	1	The maximal number of receive messages is exceeded
	Synchronous Errors	2	The maximal number of transmit messages is exceeded
	Asynchronous Errors	11	A registered message wasn't received in the given time
Memory unit	Asynchronous Errors	11	Allocate memory failed
Memory unit	Asynchronous Errors	12	Free memory failed

Tab: Name
Note that the PC downloads 64 bits of data from this tab to the PLC. 'Name' is a 64 bit (8 bytes) long label which gives an ECU a unique identity on the J1939 network.
Inputs	Arbitrary address capable – (1 bit)
	Industry group - (3 bit)
	Vehicle system interface – (4 bit)
	Vehicle system – (7 bit)
	Function - (8 bit)
	Function instance - (5 bit)
	ECU instance - (3 bit)
	Manufacture code - (11 bit)
	Identity number - (21 bit)
Extended	Selecting this enables you to create a 64-bit label according to your own requirements.

Tab: Transmit PGN
You can define up to 32 Parameter Group Numbers (PGNs) (total data length 64 bytes) that will send a message according to the Transmission Repetition rate you set.
Inputs	Data pointer This is the start of the vector that contains the data that will be transmitted from the PLC.
	Number of bytes to send (16 bit)
	Transmission repetition rate: units of 10 milliseconds. This is the rate at which the data is sent.
	Target address. The message is sent to this address in the receiving device. For a global address, the value 0xFF must be entered. (8 bit)
	PGN (PF & PS) operand (16 bit)
	Data Page (1 bit).
	Data Page Extension for the PGN (1 bit).
	Priority – operand (3 bit)
	Specifies if the Transmit PGN will be activated or deactivated after registration: 0 - Deactivated 1 – Activated (1 bit) Note that after power-up, Transmit PGN may be controlled with the Ladder function Activate Cyclic transmission of PGN.
Output	Registration succeeded

Tab: Configure Receive PGN
You can define up to 32 Parameter Group Numbers (PGNs) (total data length 64 bytes) that may be received by the PLC.
Inputs	Scan Method (0=Monitor 1=Request)
	PGN (PF & PS) – operand (16 bit)
	Data Page (1 bit).
	Max data length MI / XI – maximum number of bytes to receive (16 bit).
	Transmission repetition rate: units of 10 milliseconds. This is the rate at which the data is sent.
	Target address. The message is sent to this address in the receiving device. For a global address, the value 0xFF must be entered. (8 bit)
	Specifies if the Receive PGN will be activated or deactivated after registration: 0 - Deactivated 1 – Activated Note that after power-up, Receive PGN may be controlled with the Ladder function Transmission for Request.
Outputs	Received bit
	Address of the Transmitter (the device sending the data) (8 bit)
	Message type (global or specific) (8 bit)
	The number of data bytes received (16 bit)
	Pointer to the data-array of the message

Tab: PGN request handling
This determines if the PLC will answer PGN requests, and if so, what data the PLC will send.
Inputs	Priority – operand (3bit)
	Data length – number of bytes to send (16 bit)
	Data pointer – Pointer to the buffer with the data of this PGN (byte *).
	PGN (PF & PS) – operand (16 bit)
	Data Page (1 bit).
	Extension Data Page Extension for the PGN (1 bit).
Outputs	Received bit

Ladder Functions

You can use the ladder functions to send and receive messages in the Configuration. If, for example, you have deactivated Transmit in the Configuration, you can send a PGN using these functions.

Send PGN

Activate Cyclic PGN Transmission

If the Activate/Deactivate bit is OFF in the Configuration>Transmit PGN tab, use this function to activate it in the next scan.

SAE J1939

Configuring J1939

Ladder Functions

Send PGN

Activate Cyclic PGN Transmission

Request PGN