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jruoho's picture
Mercedes B250E support


I am interested in starting the implementation for B250E.

The car was designed when Mercedes co-operated with Tesla, so BMS and drive unit should be already well supported. Additionally Smart ED might be very similar to this one.

Is there anyone who have done some experiments with this car? What would be the easiest way to verify that the CAN bus is available in the OBD connector (before buying OVMS)? Generic adapters do not report anything from the car..

markwj's picture
The monitor-all command on a

The monitor-all command on a generic OBDII device should show something if there is data on the CAN bus. Other than advanced diagnostic tools, or OVMS, that is the simplest. But you may need to play around with bitrates to find a match (start at 500k and work down).

Another option is finding a service manual, or wiring diagram for the car. Those should have the connector pinouts.

jruoho's picture
Thank you markwj for the

Thank you markwj for the reply :)

Monitor-all command seems useful - when searching from web it's sometimes hard to figure out what to search - there is too much info with OBD. In this case MA -command was just what I needed for initial verification.

Tomorrow I should have some time to sit in the car and hopefully get it connected to ELM327-device. Then I can start the true journey to get a rid of the unreliable MB cloud!

jruoho's picture
ELM327 found something, maybe

I did initial testing with generic ELM327 (Carista branded one) and serial com SW.

Serial port worked:
ELM327 v1.5

Monitor all produced something, but I cannot yet tell weather it was data from the car or something else (data was at mostly different every time):
82 08
00 00 00 0F FF 7F 10 29
80 39 86 7F 80 81 10 87 <DATA ERROR
C0 00 C0 00 00 00 00 00 <DATA ERROR
00 00 80 00 00 80 90 0B
F0 0D 38 00 3F FC FF 7F <DATA ERROR
8: 20 00 00 82 80 18 B0
0: F8 00 FF 00 00 00 51
8: 20 00 00 82 80 28 FA
00 00 00 00 00 00 00 00
08 00 30 00 02 4F 1E 01 <DATA ERROR
80 39 86 7F 80 81 20 87 <DATA ERROR
00 00

Reading VIN failed always. With settings AT SP6 / ISO 15765-4 CAN (11 bit ID, 500 kbaud) and
AT SP7 / ISO 15765-4 CAN (29 bit ID, 500 kbaud) the result was:
>09 02

With other lower CAN speed (250kbps) the result was different:
>09 02

Next I'll try to find some info from Smart ED -forum, but any help is of course welcome :)

jruoho's picture
OVMS coming :)

Hi markwj and others,

The ELM327 testing did what it was supposed to do - verify that there is something live. Capturing is too slow with the Carista adapter, so decoding anything become difficult. So I ordered OVMS (from fasttech), as it's was the end target anyways, and it supports CAN capture out of box. It should arrive in 1-3 weeks.

If anyone who has started or completed a new vehicle module for OVMS reads this post, it would be nice to hear any comments :) How succeeded or why failed?

P.S. One important difference between any ELM327 and OVMS is Wifi - I can stay inside the house when testing and developing :)

markwj's picture
I added some comments on my

I added some comments on my recommended approach here:


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