Implementation of Isobus with IsoAgLib

Hey There,
Nowadays, many Tractors come with hydraulic steering valves pre-fitted. It is actually not very much, i think the dealers are hoping that the customers come back and buy their GPS System. I think it makes absolutely sense to provide steering control over ISOBUS in AOG,
but I can not oversee how much work it is yet.

I have done some research about implementing an ISOBUS ECU on a PC. I will dig deeper into it when I have more time this winter, but it may be interesting for others, too?
Getting started with IsoAgLib

Abstract of an Implementation of a Lighting system.
Interesting is that they have partial a virtual isobus over ethernet.
This can give us the possibility to bring together the Isobus and non-Isobus guys. Wireless Isobus over Wifi seems possible. No ISOBUS connectors to buy (expensive) and to plug in. No cabling to get damaged… Maybe we can find out more about it.

There are some implementation examples out there, mostly from universities.

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Most of my tractors don’t use ISOBUS for autosteer. I think there was a dream at one time that we could have a universal standard for interfacing with the autosteer systems on tractors so you could use anyone’s autosteer with any tractor. The reality is it’s all very much proprietary to the different brands. Most tractors use CAN bus to communicate between the auto steer controller and the various sensors and the steering valve from what I can see. I don’t know of any that use ISOBUS. As far as CAN bus goes, someone skilled in that area could no doubt determine what the PGNs are and build an interface for AOG to talk to everything directly.

Are there tractors that implement auto steering using ISOBUS? And by that I mean the ISO11783 protocol and standards, not the normal j1939 CAN bus that all tractors use. Maybe the terms are used interchangeably but my understanding is ISOBUS refers to a network and standardized services running on top of the J1939 messages on the CAN bus. And ISOBUS is a very complex and byzantine standard. Cool, but begging to be replaced by something simpler and more open.

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Danfoss provides documentation on communication. Will this data be enough to build a system for communication with Danfoss valves?

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Nice find. Probably could help someone make an arduino talk to those valves digitally instead of using a h-bridge motor driver with PWM.

I’m sure we’ll see work on this eventually. But in the short term, working directly with the analog hardware using motor drivers is quite simple, reliable, and works the same way across different valve types.

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I downloaded and installed Plus1 Guide from danfoss. I haven’t had enough time to explore it in detail yet, but it’s roughly a program for creating applications for the danfoss MC 050 110 controllers, I think also for the PLC.
I have some experience with PLC so I could easily create an analog output application with this program as valve control but we also need a danfos controller which I don’t think is cheap. In turn, with the use of some cheaper PLC, I think there will be a problem with the speed of the loop.
The program manual also includes tips on programming in C. Unfortunately, my knowledge of this language may not be sufficient to modify the arduino code, for example. However, I think there are people among our community who will be able to do it. Danfoss gives you virtually all you need to know about controlling their valves and provide the tools.
If I am not mistaken, it is also possible to reprogram the valves. So it seems that you can change the soft control via CAN to analog.

I think the specs from Danfoss are enough, all the PGN with datas are described.
The little unknow thing is that there is an addresss claim PGN which is a kind of DHCP
in J1939 and it must be tested before coding.
After, for standard appications, 2 or 3 PGN are enough.
The best thing is, for me, to test the system with a PC interface (I use PCanView and if more programmation is required EXCEL), then test the system on simple commands.Then code it in C.
I don’t know which is better : Arduino AT328P + MCP2515 or ESP32 ?
If you want further things about J1939 feel free to ask.


At work we used rpi and node-red with a CAN shield for building a CAN-Modbus bridge. Quite handy if you want to have some more logic and dead easy and fast to develop.

I believe Isobus auto steering will come and will be part of the ISOBUS TIM development.

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See this topic: CanBus for Beginners - Super Simple - #793 by RGM

Short answer, Agco tractors use the ISOBUS standard for steering, but most other brands do not. I’ve read that you can purchase a module for John Deere to allow it to steer with ISOBUS-compatible hardware.