J2411: Single-wire CAN (SWC)

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J2411: Single-wire CAN (SWC)

Postby Mark Dalton » Tue Sep 22, 2015 6:40 am

Hi There,
I'm interested in trying to decode some waveforms that I have taken from a Car. I believe the protocol is GM SAE J2411: Single-wire CAN (SWC), taken from Pin 1 on the DLC. Will any of the Protocols included in the Pico software decode the waveforms I've captured or does any one know of software that would do the job.
Thanks.
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Re: J2411: Single-wire CAN (SWC)

Postby Steve Smith » Tue Sep 22, 2015 9:35 am

Hello Mark and thank you for the post.

The CAN Protocol decode feature of PicoScope software should also apply to SWC

We need to consider the voltage states present on this single wire to ensure we select the relevant protocol.

I am not familiar with the voltage thresholds responsible for a recessive or dominant outcome. Would you know if the voltage switches from low to high or high to low?

Could you post a psdata file of your capture we can check the results?

If the voltage switches from low to high then I would select the CAN HI protocol in the serial decoding settings box, followed by Auto Set-up, where PicoScope will take of Baud rates and voltage thresholds.

AUTO SETUP.jpg


Regarding the data obtained once decoded, could you take a look here at topic11261.html

This is an interesting topic that we can all benefit from once we convert to meaningful data.

I hope this helps and any feedback you can provide would be most helpful.
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Re: J2411: Single-wire CAN (SWC)

Postby Mark Dalton » Wed Sep 23, 2015 12:58 am

psdata. file for the waveforem I captured.
Attachments
Single Wire Can.psdata
(2.02 MiB) Downloaded 179 times
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Re: J2411: Single-wire CAN (SWC)

Postby Fat Freddy » Wed Sep 23, 2015 10:16 am

One of Holdens finest. LOL :lol:

This is what I get :?:

Holden_CRUZE_2012_Petrol_20150923-0001.psdata
(2.03 MiB) Downloaded 186 times


Cheers
FF
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Re: J2411: Single-wire CAN (SWC)

Postby Steve Smith » Wed Sep 23, 2015 12:48 pm

Thank you for the continued posts

It would appear CAN HI is applicable given the rise in voltage from base 0 V to near 5 V

It decodes as expected and for easier viewing of the data, clicking on the "Export" button in the serial decoding table will enable you to export the data to a spreadsheet.

This will help with decoding for those lucky enough to have the conversion for all those values. (Converting into meaningful data)

EXPORT DATA DECODING.jpg


Below is the saved decoded data from waveform buffer 1 in an Excel spreadsheet

SWC.xls
(47 KiB) Downloaded 197 times


Take care.......Steve
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Re: J2411: Single-wire CAN (SWC)

Postby Mark Dalton » Wed Sep 30, 2015 10:07 am

Thanks for that info. Guys. Don't suppose anyone knows how the identifiers breakdon? All the ID's except one are eight digits, so I'm thinking that's four pairs of hex. If that is right does each hex pair have a particular function e.g module ID or Priority.
Much Appreciated.
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