CanBus for Beginners - Super Simple


Thanks a lot for your answer.
But I think I have the answer. Sorry for the question, I should have start by that before: this morning I have check the orbitrol of our 7060 & 7030 tractor: following a picture of the orbitrol of the 7060, but it’s exactly the same on the 7030.

The 2 left pipes goes directly to the steering cylinder. One of the right pipe goes to the cooling radiator in front of the tractor, the second goes somewhere under the cab (perhaps to the hydraulic pump ?).
No electric valve anywhere. So I’ve any knowledge of how a hydraulic steering works & a orbitrol works, but I’m pretty sure that these tractors have only pure hydraulic steering.

If I compare to our NH T7 tractor, with his Trimble RTK autosteering factory mounted, there is a lot of Eaton electric valves on the orbitrol.


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Just priced a OSPE+PVED-CLS combo along with the SASA IID sensor, I reckon this is more or less what is used in the Massey and this is what is the Valtra T4 original auto-steer ready setup as well, afaik. Around 3keur for the whole lot.

So to get this working, I basically need to acquire the WAS from the tractor bus, feed the CLS controller with the curvature command and provide CLS controller with the steering angle sensor and speed data (to enable the SIL2 safety features).

Option one is to try to hook up the steering controller and the steering wheel angle sensor to the tractor bus where the WAS info is present and also hook up AOG to the same bus to send the curvature command.

Option two is to build a separate “steering bus” where you can either hook up sensors or get info from the tractor bus and also hook up AOG to this bus to send the curvature command. If no WAS is present on the tractor, you could hook up a separate CAN-J1939 WAS to the system, maybe even put the IMU and tilt sensor on the CAN bus (OK, if you have the arduino there already you could just hook em up directly). My thought with this one was to have a CAN-based retrofit solution on the same go…

Any thoughts why this wouldn’t work before wasting my money? Of course the CLS valve need to be configured correctly for the tractor but that should be doable with the Danfoss service tool.

which plug do I need, see photos.

I = isobus cabine
J = signal iso standaard 11786
L = service (canbus)


Here’s the partial pinout for the pillar connector on the John Deere:

The implement bus is the ISO bus. The steering system SSU, GPS, and any implement plugged in appear on this bus.

The tractor bus, which isn’t always wired in (it’s not in your case) would carry information from the engine.

One of the pins (can’t remember which right now) is keyed power.

I once identified this connector type but it’s quite expensive, over $50. I ended up 3D printing a plug to fit it.

thank you very much. so if I understand correctly, the w.a.s would be on the tractor bus. the rest like hydrolic and lift on the implement. bus. like itec

to you have a 3d file of the plug

No, the WAS comes through the SSU, and it’s on the ISO bus. I found it once (see Adapting a JD Greenstar ready tractor for AOG - #12 by torriem). Seems to give degrees, so it must be calibrated somehow. I can’t remember how the calibration is done. I’ll post the STL file on a different thread later today.

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Would definaty work thats for sure. Normally that exact thing is done offen when you only have CAN from the navagtion system you are using.

But when you have a PWM valve driver, a standard PWM valve is always the cheaper way to do the same job just as good. The PVED-CL setup is a more expencive way but very tidy (No extra hoses running around)

There is no reason you cant calibrate and setup a PVED-CL via the CAN-BUS and arduino, im going to build a calibrating tool when I get time as a project.

Yeah that’s true for the PWM, but it’s not super cheap either considering the separate cutoff valves, hydraulic lines etc. Did a system with Danfoss PVHC propo last year and ended up close to 2k with everything and takes bit of fiddling around where to fit etc. And gotta admit one part is just for the sake of testing it out :upside_down_face: And price premium compared to OSPE + PWM or CAN valve without steering controller is some hundreds according to my hydraulics guy. It’s really the integration to the orbitrol that I like in the setup.

Danfoss has pretty good documentation for the calibration and interfacing, so was thinking exactly the same thing that it should be doable with arduino to set the geometries etc. The Danfoss calibration tool is available free, though, and reckon you could use any USB-CAN gateway with it, the Danfoss one is aroubd 400 eur, quite a lot for a few bucks of HW.

As for CL vs. CLS I guess the difference is the SIL2 certified safety in the CLS…

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have a problem uploading the ino file to the adruino uno.

do you have any thing I am doing wrong now

You need to load the can library, it is at the very top of this subject.

Alright, some steps forward. Wanted to be the different kid, so put a PiCAN2 Duo and a RPi3 on order, hopefully start sniffing bus data next weekend.

My target would be to try to build a safety-compliant system as a retrofit, so that you could easily build a road legal system with as little effort as possible. To achieve that with CLS controller, you need to have redundant wheel angle sensor (hence the SASA, it’s a dual CAN output angle sensor) and a doubled vehicle speed signal on the CAN (the CLS is doing cross checking between the two values as it’s one of the key parameters for the safety functions). And also an external road switch, like so:

For the controller config you need PSAC (Parameter Sector Access Code), now checking with my dealer that they’ll supply me with the OEM level code. If I understood the documentation correctly, you need that even when configuring through canbus, you need to calculate a sort of checksum. Found also some schematics for the T4, for the low-spec hitec model but I guess the basic structure applies to Versu/Direct with the armrest electrohydraulics etc. with the CAN IDs. I guess the steering valve etc. goes to CAN1, but based on that all three buses are accessible from the cab service connectors (at least).

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After some heavy googling for service manuals, found the bus diagram from a news article :crazy_face:

So looks like the initial guess wasn’t that far off, in the original setup there’s a separate steering bus as well. Reinventing the wheel is always fun :slightly_smiling_face: I would guess the WAS is on the tractor bus along with the autosteer on/off and steering sensitivity controls, and the steering controller picks up those messages and relays to the CL valve, same thing with the autoguide display hooked up to Isobus for the steering controls etc. So AOG would take the place of the Isobus-connected display and the arduinos would play the part of the steering controller…

Something like this what I had in mind. Do I need isobus for anything, guess not?

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I didn’t think I needed it in the Fendt but Tony pointed out it was required if I needed to activate the autosteer from the tractor’s management system. I’ve no idea if the Valtra system is the same though.

The WAS has to be direct on the steering bus, or hard wired to it i’m pretty sure other wise your just asking for trouble.

If you want all that safety stuff to work it needs two of everything, 2 x WAS, 2 x SASA, 2 x Speed, etc and they must be different sensors / CAN-IDs.

What tractors have a CLS from factory?

JCB fastrac 4000 series have pved-cls and I think some case and new Holland also but not sure what models.

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The SIL2 safety features are sort of out of professional interest from previous non-agriculture work, spent way too many hours on SIL2 related project meetings so it’s like a tempting suicide plan :crazy_face: Danfoss is not marketing the CL anymore, so I guess it’s phasing out with some schedule.

-SASA is a dual CAN (the IID version) so it appears as two separate sensors.

-WAS is already installed on the machine, so it’s gotta be talking to the tractor bus as it is disengaging the diff locks based on steering angle etc, hence the idea for the schematic above. I would guess the sensor itself might well be a dual sensor (it’s the same as in Fendt). So if I hook it up to the steering bus directly I’ll need to send the values to the tractor bus… Looking at the parts catalogue, looks like 6 wires running from the sensor so keeping my hopes up it’s a dual.

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Had a test with AgOpenGPS steering the Fendt S4 724 today correctly.

Had the BNO085 IMU running with the main steering Arduino connected to the V-Bus this was sending the steering commands plus sorting the cutting out when steering wheel is moved etc.

I had a second Arduino connected to the ISO-Bus this was my remote engage so I can engage via the Arduino steer engage button, or the Fendt Teach-In or the arm rest button they all do the same thing.

The Fendt WAS and the steering valve must be calibrated through the dash before it will work nice tho. The standard AOG counts per degree and max steer angle in AOG still work and must be set in AOG etc.


That is very smooth!

Are you sending the AOG requested steer angle directly to the K bus or doing something similar to mine, running a variable with the AOG parameters then sending that?

Sending the steer angle directly. I had it running on another SCR that was abit rougher and couldn’t get my brain into gear to think about & program the steer speed like you have done. Swapped tractors and it was smooth as so thinks it’s more the tractor calibration that causes it.

I’ll find another tractor around that’s never had a GPS system in it, calibrate it from scratch and see what happens I guess

Does the steering sensitivity setting have anything to do with the difference between two tractors? I understood that the command from AOG is for the steering angle but the steering speed is not controlled? Or is this smoothness something completely different from speed?

I have no idea if the OEM screen “sends” settings to the steering controller or how would it take the setting into account. Does the setting on the screen have any effect in this project?