CANFD communication with vxlapi (about "xlCanTransmitEx" function)

[kojiamano]

Thank you again!

I'll check it.

[kojiamano]

Hello Troy

>5.5.2 XL_CAN_TX_MSG
>msgFlags

When I transmit the canfd standard message, the msgFlags should be  "1"?

 =>it's "XL_CAN_TXMSG_FLAG_BRS "?

And when the message is extended CAN FD, the msgFlags should be  "4"?

 =>it's "XL_CAN_TXMSG_FLAG_EDL"?

The vxlapi.dll seems to accept many numbers within 0 to 1000.

I tried to input the numbers as a msgFlags one by one in the For-loop.

The dll sometimes returned error, but sometimes returned no error..

Best regards

Amano@home

[TroyK · Accepted solution]

In the CAN-FD spec it identifies bits in the CAN-FD frame "control field".  Two of the bits in the control field are:

EDL - Extended Data Length (> 8 bytes)

BRS - Bit Rate Switch (data bit-rate > arbitration bit-rate)

They are also mentioned in section 5.5.4 of the XL Driver Library documentation.

These bits are only relevant in CAN-FD frames.  The msgFlags in the CAN-FD transmit event structure allow you to specify what these flags will be.

#define XL_CAN_TXMSG_FLAG_EDL          0x0001  // extended data length

#define XL_CAN_TXMSG_FLAG_BRS          0x0002  // baud rate switch

#define XL_CAN_TXMSG_FLAG_RTR          0x0010  // remote transmission request

#define XL_CAN_TXMSG_FLAG_HIGHPRIO     0x0080  // high priority message - clears all send buffers - then transmits

#define XL_CAN_TXMSG_FLAG_WAKEUP       0x0200  // generate a wakeup message

As you can see from this excerpt from the header file, no value for 4 is defined.

Classic CAN frame would have msgFlag = 0

CAN-FD frame with Extended Data Length and Bit Rate Switch would be sent with msgFlag = 3

[GoKu25]

Hi, I have been trying to transmit CanFD data from LabVIEW to CANape on the same computer via virtual CAN. I used your code and I am half way there.

I am only able to send 8 bytes of data. I have set the tag to x440 and the msg_flag to 0(I believe this is for extended CAN, other numbers don't work mostly). 

Have a look at my VI. I wish to send more than 8 bytes and read it in CANape. I configured a dbc file with standard CAN FD message with few signals for testing

AS you can see from the canape screenshot, the length remains 15 and if i change the dlc to 12, 12 bytes of data is transmitted, however only 8 contain the values.

[TroyK]

Please make sure you understand how the EDL and BRS flags work in a CAN-FD frame and when they need to be set. Also make sure you understand how to set those flags in the msgFlags parameter of transmit message.

The answer is in my response which has been marked as the solution in this thread (immediately above your question).

[LABFIL007]

Hello,

Can you attach the "CANFD.zip" for the Labview version 2017

thanks

regards

F.Garraud

[kojiamano]

I saved in labview 2017. Please have a look.

[CarlosLuevanoSanchez]

Hi guys, I have problems to transmit CAN FD message with vxlapi in LabVIEW. The function xlCanTransmitEx is transmitting successful but just the ID Request and not the data. Would you mind if you share your development in LabVIEW 2017, please? Just to look what is the format to send XLcanTxEvent by xlCanTransmitEx function.

I will appreciate your help.

Best

[LABFIL007]

Hello Carlos,

My development is on progress , I have the Same Problem I cannot send any CAN FD frames for the moment .

my status is the same as before

regards

Frederic

[GoKu25]

Have you made sure that CANape is configured to receive CAN FD data?