Decoding CAN Bus Data Using the PicoScope 

Man, I see your remarks everywhere I go, ha ha.

Thanks for sharing that information!

Thank you. I wish I new more about marine protocols, but I don't know the answer to that question. Maybe you could contact Pico directly and ask them.

I usually use the 4425 or the 4225. The amount of time that you can record for has to do with the number of samples you are requesting. If you request a higher sample rate, then you cannot record for as long because you are limited by the memory of the device. If you request a lower number of samples, then you can record over a longer time.

You can ground on either pin. Ideally, they should both have zero volts. However, the real question is what is the voltage at those pins? If you are concerned at all about voltage drops on the ground side, you should verify that the voltage at each of those pins is within about 50mV of the voltage at the negative battery terminal. The negative terminal is always the best place to ground for most accurate readings, but once you have verified your voltage at pins 4 and 5, you can use them as your reference point.

By taking it to this level, you can determine whether the CAN bus is operating correctly and messages are being sent and received successfully--but that is about all. From here, you would need software with the correct file in order to translate these messages into English. That is basically what a scan tool does.

hi Billy, any futher steps you found already here? I am in the same process with the need to analyse this data. All commercial Can-H & Can-L cable hardware-sniffers are pretty expensive. Thx!

Yes, but it is very tedious to do it manually. There are software programs that can do it. In fact, that is what an OBD II scan tool is doing-interpreting the CAN data and turning it into readable information. OBD II data is public domain and can be accessed by anyone. For other network data, you would need to have the correct files from the manufacturer in order to translate the hexadecimal messages into something we can understand. The manufacturers do not usually give that out.

I have another video that talks about finding errors in the CAN bus. I think it will answer your question. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-dfPl2kWBF1U.html

Yes, but it would be tedious. That is what a scan tool does.

@@JustinMillerAutomotive thanks

There are ways to do that. If you don't have manufacturer's files (which you would not, unless you worked for them), then you would have to manually decode the messages. This is a very long and arduous process. Often, this can be done by removing modules from the network or changing something, and then carefully comparing the messages to find differences. You wouldn't do this for fun. You would have to be very motivated.

CAN became the required protocol for the diagnostic network beginning in 2008. A few cars began using it a year or two before that, but not in 1995. Early for OBD II vehicles used the J1850 PWM protocol, which is a two-wire network on pins 2 and 10 of the DLC. If I remember correctly, the voltages switch from 0-5 volts.

I meant to say "early Ford OBD II vehicles."

I think the 480 mV was just there by default. When the hysteresis is set to a lower number, the software will be more sensitive to errors in the CAN messages. If I want to detect ALL possible errors, I will set the hysteresis at zero. If I want it to be more fault-tolerant, I will choose a higher number.

@@JustinMillerAutomotive Thanks for your answer! It helps me a lot to solve my wonderings. I will subscribe your channel! Thanks. haha :)

It is the automotive Pico. There are other scopes that you can limp by on, but nothing compares to the automotive PicoScopes. No cheap scopes can decode the CAN bus like the Pico software, either. You can buy a 2-channel PicoScope with leads (without buying the whole kit) for a lot less than $2500. You can find a standalone scope or a starter kit on our website - CatchaWave.com. Call i you have questions!