CAN Module read vehicle RPM with ECU toolkit

[sfrosty]

[sfrosty · Accepted solution]

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@JGruenberg wrote:

Off chance it's not a linear scaled number and is a IEEE 754 floating point (which I've never seen on an automotive network), you'd get 599.36 which seems not implausible.

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That's it! It's a IEEE 754 floating point data format. I used the IEEE-754 Floating Point Converter and included information to decipher and write my LabVIEW code (URL attached). Thanks for sending me the 599.36 value which I used to verify operation.

IEEE 754 floating point calculator and info to write your own LabVIEW code:

https://www.h-schmidt.net/FloatConverter/IEEE754.html

[sfrosty]

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@Minions wrote:

Additionally, you will need to know if the information is being presented as Big or little endian.  Do you happen to know the Baud rate and BTR values?  All of this information should be present within the file extensions that Hooovahh mentioned.  Also, a .MAP file might also be benefit.

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I have the endianess and baud rate, and the A2l file specific to the vehicle, however, I can't  find any of the parameters I apparently need to communicate listed in the A2l file. Looks like I still need CRO ID, Data Transfer Object, DTO ID and Station Address. I can most probably get access to the seed file. The NI A2L Viewer lists a CCP folder under Cal Pages, so I'm assuming the ECU protocol is CCP. The CCP folder is empty. I have some feelers out.

[Hooovahh]

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@sfrosty wrote:

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however, I can't  find any of the parameters I apparently need to communicate listed in the A2l file. Looks like I still need CRO ID, Data Transfer Object, DTO ID and Station Address.

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As far as I know the A2L defines the CRO ID and DTO ID, I'm unsure if the other parameters are in there or not.  I've also seen some DBCs that define what these IDs are, even if they aren't really used in the signal API.

[JGruenberg]

No need for complicated math -- you can do a simple type cast:

[sfrosty]

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@Hooovahh wrote:

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@sfrosty wrote:

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however, I can't  find any of the parameters I apparently need to communicate listed in the A2l file. Looks like I still need CRO ID, Data Transfer Object, DTO ID and Station Address.

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As far as I know the A2L defines the CRO ID and DTO ID, I'm unsure if the other parameters are in there or not.  I've also seen some DBCs that define what these IDs are, even if they aren't really used in the signal API.

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Don't see the CRO ID or DTO ID in the A2L. Still looking for info. Don't have a DBC file, is that something I should look to acquire?

[sfrosty]

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@JGruenberg wrote:

No need for complicated math -- you can do a simple type cast:

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Thank you for the response. I'll keep it in mind. However, I don't see how it would apply in this case. Thanks again!

[Hooovahh]

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@sfrosty wrote:

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Don't see the CRO ID or DTO ID in the A2L. Still looking for info. Don't have a DBC file, is that something I should look to acquire?

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I've never needed the DBC for CCP or XCP communication since the A2L file for me has always contained the information needed.  I was just suggesting another way to possibly get the information you are looking for.

[sfrosty]

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@Hooovahh wrote:

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@sfrosty wrote:

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Don't see the CRO ID or DTO ID in the A2L. Still looking for info. Don't have a DBC file, is that something I should look to acquire?

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I've never needed the DBC for CCP or XCP communication since the A2L file for me has always contained the information needed.  I was just suggesting another way to possibly get the information you are looking for.

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Have you ever communicated with a GM, Ford, or Chrysler vehicle utilizing only the information from the A2L file? For example, acquiring engine RPM or Throttle Position. I know these are available via OBDII; just using as an example that the output can easily be verified.

[Hooovahh]

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@sfrosty wrote:

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Have you ever communicated with a GM, Ford, or Chrysler vehicle utilizing only the information from the A2L file? 

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Yes, not specifically to read engine RPM but other diagnostic information stored in DIDs, and PIDs.

Edit: sorry wrong protocol, but yes I've used it to read XCP information with nothing other than an A2L.