How to Configure CAN FD Custom Baud Rate in Automotive Diagnostics Command Set

Updated Mar 7, 2019

Reported In

Hardware

  • USB-8502
  • PCI-8512
  • PCI-8513
  • PXI-8512
  • PXI-8513
  • NI-9860
  • NI-9862

Software

  • Automotive Diagnostic Command Set Toolkit

Driver

  • NI-XNET

Issue Details

I am using an USB-8502 and NI-XNET. I want to implement custom baud rate on CAN FD protocol using Automotive Diagnostics Command Set. But I don't know how to configure with Open Diagnostic on CAN FD.vi. How can I configure it?

Solution

In order to implement custom baud rate with Open Diagnostic on CAN FD.vi, you need to configure 3 parameters: IO Mode, FD Baud Rate and Max DLC.
 

1. Set IO mode as CAN FD+BRS.
Custom baud rate is baud rate and BRS based on CAN FD. Regarding more information about custom baud rate, see Additional Information.


2. Input custom baud rate in FD Baud rate parameter. It is composed in hexadecimal, so if you want to display and enter hexadecimal, follow instructions below:
1. Right-click FD Baud Rate constant or control and select Properties.
2. Navigate to Display Format tap.
3. Change type to Hexadecimal.
4. Click OK.

3. Change Max DLC to appropriate number.
Max DLC is the maximum CAN frame length to be used in CAN FD diagnostic communication. For the CAN FD or CAN FD+BRS settings of the IO Mode, this limits the frame size for transmission of diagnostic requests. Remember that Max DLC is 8 by default, so you need to change Max DLC if you use data longer than 8 bytes.

Additional Information

A custom baud rate is a 64-bit number in hexadecimal, composed with baud rate and BRS (Bit Rate Switch). BRS denotes the point in the CAN frame where the bit rate is switched from the nominal rate (used for the Arbitration ID and header) to the data rate.
If you want to generate a custom baud rate with NI-XNET, refer to the following document: Error or Incorrect Frames When Using NI-XNET in CAN FD & BRS

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