Not able to write CanFdMessage to blf.

[Deepen M]

Hi Tobias,

I am writing CAN FD frames to blf but when i analyze the blf file in CANalyzer all seems to be wrong.

e.g.

Event type is CAN frame.

Data length is always 8.

Data is always 8 byte even if i copied 64 byte data. Below is a snippet of code. Please give your input.

    auto* stdCAN = new Vector::BLF::CanFdMessage;
    stdCAN->objectTimeStamp = time_ns;
    stdCAN->channel = channel;
    stdCAN->id = messageID;
    stdCAN->objectType= Vector::BLF::ObjectType::CAN_FD_MESSAGE;


            if (size > 64)
                return false;
            else if (size > 48)
                stdCAN->dlc = 15;
            else if (size > 32)
                stdCAN->dlc = 14;
            else if (size > 24)
                stdCAN->dlc = 13;
            else if (size > 20)
                stdCAN->dlc = 12;
            else if (size > 16)
                stdCAN->dlc = 11;
            else if (size > 12)
                stdCAN->dlc = 10;
            else if (size > 8)
                stdCAN->dlc = 9;
            else
                stdCAN->dlc = 8;


            stdCAN->dlc =size;
            stdCAN->validDataBytes= size;
            stdCAN->frameLength = size;
    memcpy(&stdCAN->data, data, stdCAN->dlc);
    hFile.write(stdCAN);
    return true;

‌

[Tobias Lorenz]

I'll check it.

[Tobias Lorenz]

Hello Deepen M,

In your code, there are some issues, we should fix first.

stdCAN->objectType= Vector::BLF::ObjectType::CAN_FD_MESSAGE;

This doesn’t need to be set, as it happens in the constructor of CanFdMessage already.

stdCAN->dlc =size;

This is likely wrong, as you already set it in the if/else statements. Or you would make the if/else statements useless, if you set another value afterwards.

stdCAN->frameLength = size;

frameLength is actually the message length in ns, not the byte size. You don’t need to set it.

memcpy(&stdCAN->data, data, stdCAN->dlc);

You should use stdCAN->size here instead.

Do you agree? Can you test again with these changes?

Bye

Tobias

[Deepen M]

Hi Tobias,

I changed the code and give it a run but the result is same. Please find the updated code below.

auto* stdCAN = new Vector::BLF::CanFdMessage;
stdCAN->objectTimeStamp = time_ns;
stdCAN->channel = channel;
stdCAN->id = messageID

        if (size > 64)
            return false;
        else if (size > 48)
            stdCAN->dlc = 15;
        else if (size > 32)
            stdCAN->dlc = 14;
        else if (size > 24)
            stdCAN->dlc = 13;
        else if (size > 20)
            stdCAN->dlc = 12;
        else if (size > 16)
            stdCAN->dlc = 11;
        else if (size > 12)
            stdCAN->dlc = 10;
        else if (size > 8)
            stdCAN->dlc = 9;
        else
            stdCAN->dlc = 8;


        stdCAN->validDataBytes= size;
memcpy(&stdCAN->data, data, size);
hFile.write(stdCAN);
return true;




Please let me know if you have any input.

‌

[Deepen M]

PFA for the CANalyzer screenshot.

‌

[Tobias Lorenz]

I just checked the definition of the CanFdMessage class. The class is able to transport a CAN message and a CANFD message. Difference is that in a CANFD message, you have to set

canFdFlags = Vector::BLF::CanFdMessage::CanFdFlags::EDL

Let’s try this

[Deepen M]

Thanks Tobias for the input. Now it is working.

[Deepen M]

Issue is fixed. Need to set CanFdflag in order to write CAN FD frames.

[Tobias Lorenz]

Great. Thanks for the feedback. :-)