[Ovmsdev] Model S Can Bus Specs

Oliver Weidmann oliver at sdds.ch
Thu Jan 2 19:06:52 HKT 2014



Thanks – I had to do quite some trial-and-error to find the bus specs. Model S looked like a EE-lab on wheels ;)


It looks like there are several bus-pins available on the diag-connector. “Our” can wires are on the right side – in the same place as in the roadster – but the other pins seems to transmit bus signals as well. The two pins just left of “our” can pins are transmitting on +/- 4V. And on the far left side there are probably additional can pins. Could mean that the S is running multiple can buses (Roadster has 3 different can buses running). Somewhere I read that Model S also has a “BEAN Bus” (a Toyota specific standard running on a single wire - http://elinux.org/BEAN_Bus). But for now, we should stick to the can signals ;)


I’ll do a bus dump of “our” can wires today and send you the results. Maybe I can even log a short drive with Model S.






Von: ovmsdev-bounces at lists.teslaclub.hk [mailto:ovmsdev-bounces at lists.teslaclub.hk] Im Auftrag von Mark Webb-Johnson
Gesendet: Donnerstag, 2. Januar 2014 01:57
An: OVMS Developers
Betreff: Re: [Ovmsdev] Model S Can Bus Specs




Now, this makes my new year happy. The 512kbps (vs 1Mbps) explains the previous report I heard of can bus errors when plugged in and active at the assumed (roadster ) speed of 1Mbps. I think Tesla's switch to 512kbps is sensible - allows a lot more standard equipment to be connected.


I would love to see a can bus dump (a few minutes, with the car on).


Regards, Mark

On 1 Jan, 2014, at 11:27 pm, "Oliver Weidmann" <oliver at sdds.ch> wrote:

A good new year to everyone on this mailing list.


I finally found some time to play with my Model S and search for bus wires.


Well here are some details:


The bus connector is located underneath the touch screen (grab the storage shelf hole and pull STRAIGHT down).


The connector is the same as in the Roadster. When reading the bus be sure to attach CAN HIGH, CAN LOW and CAN GROUND (you can use normal GND, see image). If you don’t use CAN GROUND, the car will get confused. The Roadster doesn’t care if you use CAN GROUND, but Model S seems to be a bit sensitive on this topic. Also be careful with the +12V pin. If you produce a short your instrument panel screen will eventually go black as they seem to share the same fuse (which is the 5A fuse #49 in fuse box #2). 


Ok, once all wires are in place and the car is still running, it’s time to read some data. Bus speed is 500 Kbit/s (vs. 1Mbit/s in the Roadster).


A fist quick look at the data showed me the following:


ID 2C8 looks like the actual charge settings.


67 32 = min Standard 

67 5A = max Standard 

67 63 = one tick before max Range 

27 64 = max Range  


Obviously the second bit bit represents the percentage of the charge settings (32h=50dec=50%, 64h=100dec=100%). It seems to be a readout only variable, as sending messages to ID 2C8 didn’t change the charge settings.


Maybe this is the first step for OVMS for Model S? Well, we’ll have to see ;)







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