Twido ExtremeThe all-terrain controllerCAN J1939Communication protocol

Schneider Electric 2- Division - Name – Date

What is CAN J1939?

Definition : The J1939 protocol comes from the international Society of Automotive Engineers (SAE) and works on the physical layer with CAN-highspeed according to ISO11898.

●The particular characteristics of J1939 are:

● 29-bit identifier

● Peer-to-peer and broadcast communication

● Transport protocols for up to 1785 data bytes

● Network management

● Definition of parameter groups

● Baud rate : 250 kBaud

Schneider Electric 3- Division - Name – Date

What is CAN J1939?

●J1939-based protocols are used in:

● Diesel power-train applications

● In-Vehicle networks for trucks and buses

● Agriculture and forestry machinery

● Truck-Trailer connections

● Military vehicles

● Fleet management systems

● Recreational vehicles

● Marine navigation systems

Schneider Electric 4- Division - Name – Date

CAN J1939 : glossary

●Main abbreviations :

● ECU : Electronic Control Units– A computer based electronic assembly from which SAE J1939

messages may be sent or received.

● PDU : Protocol Data Unit– This correspond to the Message Format (PDU Format = peer to peer or

broadcast) and indicate either the destination address or the group extension (PDU Specific).

● PG : Parameter Group– Description of application data to be exchanged by the ECUs. Each

parameter group is addressed uniquely via a number (PGN).

● PGN : Parameter Group Number.

– A PGN identifies a message's function and associated data.

● SPN : Suspect Parameter Number– Each defined signal is called an SPN and is assigned to a PG.

●Example :

● For the PG: Engine Oil

●SP: Engine Oil Pressure

●SP: Engine Oil Temperature

Schneider Electric 5- Division - Name – Date

CAN J1939 : message format

* Data Page : DP bit expands the number of available parameter groups.

PriorityParameter Group Number

PGNSourceAddress

Destination Address / Group

ExtensionReserved Data Page* PDU Format

Parameter Group Number (PGN)

Data

Protocol Data Unit (PDU)

SAE J1939 Message (CAN based)29bit CAN-Identifier

Schneider Electric 6- Division - Name – Date

J1939 Parameter Group (global)

●Example from Document J1939/71:

Engine intercooler thermostat opening8Engine intercooler temperature7Turbo Oil temperature5,6 Engine Oil Temperature3,4Fuel Temperature2Engine coolant temperature1PGN Data Bytes

Description of data :

65.262 (00FEEE16)PG number6Default priority238 (EE16)PDU specific254 (FE16)PDU format0Extended Data page0Data page8 bytesData length1sTransmission rateEngine Temperature – ET1NameValueAttribute

Schneider Electric 7- Division - Name – Date

How the messages are exchanged ?

●2 messages format :

● Peer to peer

● Broadcast

● Is the exchanged mode standardized ?

● YES, the specification of the communication, broadcast or peer-to-peer, is a property of the parameter group used.

Schneider Electric 8- Division - Name – Date

How the messages are exchanged ?

Message

1:1

PEER to PEER

ECU A ECU C

ECU A

ECU B

ECU C

ECU #-1

ECU #

ECU C

Schneider Electric 9- Division - Name – Date

How the messages are exchanged ?

1:#

BROADCAST

ECU A

ECU B

ECU #

MessageECU A

ECU B

ECU C

ECU #-1

ECU #

ECU C

ECU B

ECU #-1

ECU #

Schneider Electric 10- Division - Name – Date

CAN J1939 Device Address

●Some standardized addresses :

● Max. number of addresses are 254 (0 … 253 for process)

● Address 254 (NULL) and 255 (Global Address) cannot be assigned to an ECU.Used for e.g. Broadcast addressing or NULL as address for Network management.

● Addresses 0 to 127 are reserved for ECUs that are most commonly used on all vehicles (onboard or offboard)

● Addresses 128 to 247 are reserved for industry_specific assignment and dynamically acquired addresses

● Addresses 248 to 253 are reserved for ECUs that are most commonly used on all vehicles (onboard or offboard)

Schneider Electric 11- Division - Name – Date

Limitations with Twido Extreme

●CAN J1939 features :

● 254 ECUs (max number of addresses)

● Message length : up to 1785 bytes (BAM messages > 8 bytes) :

●Diagnostic messages●Self-configurable ECU supported

●BAM* messages

●CMDT** messages

●Limitations with Twido:

● 32 ECUs

● Message length : up to 8 bytes (no transport protocol) :

●No diagnostic messages

●Self-configurable ECU notsupported

●No BAM messages

●No CMDT messages

* BAM : Broadcast announce message

** CMDT : Connection Mode Data Transfer

Schneider Electric 12- Division - Name – Date

Advantages of CAN J1939

●Advantages :

● Complies with SAE J1939 standards � all is standardized

● Allows cabling and implementation gain

● Especially dedicated for trucks and mobile vehicles

● More and more vehicles will adopt this protocol as a standard in the next years (military, garbage trucks, …)

● Ensures CAN device interoperability

Schneider Electric 13- Division - Name – Date

Marine application

●Solution proposed

● PLC M340 in order to watch on and to archive information and warnings.

● HMI

● 2 Twido Extreme used as Modbus -CAN J1939 gateway in order to watch on the information of the 2 motors installed on the barge (Koller for the generating set and John Deere for the hydraulic propulsion pump). 1 TwidoExtreme is connected on each motor

● Modbus Network between the M340 and the 2 Twido Extreme

CanJ1939

UC Treatment M340

Koller motor

Modbus

Twido Extreme

HMI

Twido Extreme

CanJ1939

John Deere motor

Schneider Electric 14- Division - Name – Date

Gen-set application

●Application : Diesel generators

●Key Factors : CANJ1939 communication

CanJ1939Vehicle’s engine

Twido Extreme

UC Treatment

Modbus

Schneider Electric 15- Division - Name – Date

CAN J1939 : Appendix 1

Twido Extreme is an ECU of the Group 5 : Industrial-Process Control-Stationary

Schneider Electric 16- Division - Name – Date

CAN J1939 : Appendix 2

Adjust year6Adjust local minute offset7Adjust local hour offset8

Adjust day5Adjust month4Adjust hours3Adjust minutes2Adjust seconds1PGN Data Bytes

Description of data :54.528 (00D50016)PG number6Default priorityDestination addressPDU specific213 (D516)PDU format0Extended Data page0Data page8 bytesData lengthAs neededTransmission rateTime/Date Adjust – TDAName

ValueAttribute

●Example J1939 Parameter Group (specific) from Document J1939/71:

Global PG (PDU format ≥240) ���� Broadcast messageSpecific PG (PDU format ≤ 240) ���� Peer to peer message

Schneider Electric 17- Division - Name – Date

CAN J1939 : Appendix 3

●Example J1939 Signals:●Signal description “Engine coolant temperature”

Data length : 1 byteResolution : 1°C/bit gain, -40°C offsetData Range : -40°C to +210°CSPN : 110Type : Measured

●Signal description “Fuel temperature”Data length : 1 byteResolution : 1°C/bit gain, -40°C offsetData Range : -40°C to +210°CSPN : 174Type : Measured

●Signal description “Engine oil temperature”Data length : 2 byteResolution : 0,03125 °C/bit gain, -273°C offsetData Range : -273°C to +1735,0°CSPN : 175Type : Measured