1. SAE J1939 / ISO 11783 Tractor ECU Lecture 7 Tractor ECU
ISO Part 9
BAE
Spring 2009
Instructor: Marvin Stone
Biosystems and Agricultural Engineering
Oklahoma State University
Feb 18, 2009
BAE

2. Network Context of the TECU
Feb 9, 2009
BAE

3. ISO 11783 Tractor Electronic Control Unit (TECU)
TECU Functions
Transfers data and command messages to/ from the tractor to the implement bus as appropriate for the Tractor ECU’s classification
Represents the tractor on the implement bus, including access to the Virtual Terminal
Sends requested tractor information on the implement bus
Parses messages and commands from the implement bus appropriate for the tractor design
Identifies its classification and message set to all ECUs on the implement bus on request using a tractor facilities message (see ISO ).

4. ISO 11783 TECU Tractor Classification
Specifies Tractor classes of ISOBUS capability
A Tractor ECU classification informs the operator of a tractor’s compatibility with implements
Each classification identifies a minimum set of messages that a tractor shall provide to connected implements on the implement bus
The set of messages a classified Tractor ECU has to provide depends on the tractor’s features
The Tractor manufacturer may provide additional messages without providing the complete set of messages of the next higher class of Tractor ECU

5. Class 1, tractor basic information
Shall provide following internal tractor measurements
Power management:
key switch state;
maximum time of tractor power;
maintain power request.
Speed information:
wheel-based implement speed;
ground-based implement speed;
engine speed: message transmission rate shall be 100 ms.
Hitch Information:
rear hitch position;
rear implement in-work indication.
PTO (power take-off) information:
rear PTO output shaft speed;
rear PTO output shaft engagement.

6. Class 1, tractor basic information - Continued
Lighting:
left-turn signal lights;
right-turn signal lights;
marker light;
left stop light;
right stop light;
implement rear work light.
Language-specific parameter storage in tractor ECU, VT or both.

7. Class 2, enhanced tractor information
Shall provide all of the class 1 messages and
Time & date,
Wheel & ground based distance & direction,
Rear hitch draft and lower link forces,
Complete set of lighting commands
Auxiliary valve (EHRs) estimated and measured status messages

8. Class 3, command from the connected implement
Shall provide all of the class 1 & 2 messages and
Rear hitch commands,
Rear PTO rpm set-point & engagement commands,
Auxiliary valve (EHRs) command messages,
An implement or the task controller can request the adjustment of the power source as well as the hitch position
A Tractor - Implement combination can perform the same as a self-propelled machine

9. TECU Additional Features
Interface options to TECU classifications 1 to 3 are:
Option (F) -- Front hitch & Front PTO
Option (N) -- Navigation / location
TECU shall also provide the following capabilities:
Implement electrical power control
Implement lighting control
Safe mode operation

10. ISO 11783 TECU Electrical Connections

11. ISO 11783 TECU “Fall-Back” for Lighting

12. Safe-Mode Operation
Upon loss of power or communication with the tractor, the implement shall assume a condition of fail-safe operation. The interruption, re-establishment after interruption or fluctuation in any manner whatsoever of the power supply to the implement shall not result in a dangerous situation. Neither shall a fault in the control logic, nor failure or damage to the control circuit, be allowed to lead to danger.
Feb 9, 2009
BAE

13. Safe Mode Requirements
The implement shall not start unexpectedly.
The implement shall not be prevented from stopping if the command has already been given.
No part of the implement, or a piece held by the implement, shall fall or be ejected.
Automatic or manual stopping of any moving part shall be unimpeded.
The protection devices shall remain fully effective.
Remote-controlled implements shall be designed and constructed to stop automatically in the event of the driver losing control.
The operator shall have the ability to override implement-controlled systems.
Feb 9, 2009
BAE