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CAN FD Replay

Replay logged CAN FD messages


Vehicle Network Toolbox: CAN FD Communication

  • CAN FD Replay block


The CAN FD Replay block replays logged messages from a .mat file to a CAN network or to Simulink® as a bus signal. For more information on Simulink bus objects, see Composite Signals (Simulink). You need a CAN FD Configuration block to replay to the network.

To replay messages logged in the MATLAB® Command window in your Simulink model, convert them into a compatible format using vntslgate and save it to a separate file. For more information, see Log and Replay CAN Messages.


You need a license for both Vehicle Network Toolbox™ and Simulink software to use this block.

Replay Timing

When you replay logged messages, Simulink uses the original timestamps on the messages. When you replay to a network, the timestamps correlate to real time, and when you replay to the Simulink input port it correlates to simulation time. If the timestamps in the messages are all 0, all messages are replayed as soon as the simulation starts, because simulation time and real time will be ahead of the timestamps in the replayed messages.

Other Supported Features

  • The CAN FD Replay block supports the use of Simulink Accelerator™ mode. Using this feature, you can speed up the execution of Simulink models. For more information on this feature, see Acceleration (Simulink).

  • The CAN FD Replay block supports the use of code generation along with the packNGo function to group required source code and dependent shared libraries. For more information, see Code Generation.

Code Generation

Vehicle Network Toolbox Simulink blocks allow you to generate code, enabling models containing these blocks to run in Accelerator, Rapid Accelerator, External, and Deployed modes.

Code Generation with Simulink Coder

You can use Vehicle Network Toolbox, Simulink Coder™, and Embedded Coder® software together to generate code on the host end that you can use to implement your model. For more information on code generation, see Build Process (Simulink Coder).

Shared Library Dependencies

The block generates code with limited portability. The block uses precompiled shared libraries, such as DLLs, to support I/O for specific types of devices. With this block, you can use the packNGo function supported by Simulink Coder to set up and manage the build information for your models. The packNGo (Simulink Coder) function allows you to package model code and dependent shared libraries into a zip file for deployment. You do not need MATLAB installed on the target system, but the target system needs to be supported by MATLAB.

To set up packNGo:


In this example, gcs is the current model that you want to build. Building the model creates a zip file with the same name as model name. You can move this zip file to another machine and there build the source code in the zip file to create an executable which can run independent of MATLAB and Simulink. The generated code compiles with both C and C++ compilers. For more information, see Build Process Customization (Simulink Coder).


On Linux® platforms, you need to add the folder where you unzip the libraries to the environment variable LD_LIBRARY_PATH.



Configure your CAN FD Configuration block before you configure the CAN FD Receive block parameters.

File name

Specify the name and path of the file that contains logged CAN FD messages that you can replay. You can click Browse to browse to a file location and select the file.

Variable name

Specify the variable saved in the MAT-file that holds the CAN FD message information.

Number of times to replay messages

Specify the number of times you want the message replayed in your model. You can specify any positive integer, including Inf. Specifying Inf continuously replays messages until simulation stops.

Replay messages to

Specify if the model is replaying messages to the CAN network or an output port. If replaying to the CAN network, you must also specify a device. If replaying to the model through an output port, the output is a Simulink bus signal.


Select the device on the CAN network to replay messages to. This filed is unavailable if you select Input port for Replay message to option.

Sample time

Specify the sampling time of the block during simulation, which is the simulation time as described by the Simulink documentation. This value defines the frequency at which the CAN FD Replay block runs during simulation. If the block is inside a triggered subsystem or to inherit sample time, you can specify –1 as your sample time. You can also specify a MATLAB variable for sample time. The default value is 0.01 (in seconds).

Introduced in R2018b