How to receive and transmit multiple CAN-Messages in a single time-step on a Raspberry Pi 3B?

Hi all,

I am trying to set up a Simulink model on a Raspberry Pi 3B with Matlab 2021b. The model has to receive sensor-data and transmit results via a CAN-Bus with a bitrate of 500000. As CAN-Hat I am using the 2-CH CAN HAT from Waveshare (https://www.waveshare.com/wiki/2-CH_CAN_HAT).

The model has to send and transmit multiple CAN-messages in a single time-step. The implementation essentially looks like this:

The CAN_read subsystem runs at a shorter sample-time than the rest of the model to ensure all messages are received.

In the testet scenarios the model is removed so that I can enable mat-file logging and the system runs without task-overruns.

With the CAN_write subsystem commented out, the CAN messages are received normally. A Signal may look like this:

With the CAN_write subsystem active the same signal will look like this:

When comparing both plots it can be seen that with CAN_write enabled there are large gaps between the received messages of this signal.

Does anyone know what may cause this behavior, and how I can solve this?

Can I even use Receive- and Transmit-Blocks in such a manner? Is it not recommended to use more than one CAN-Transmit block?

Answer 1

[Enrico Landolfi]

Hi,

I have a similar problem with more than one can message featured by more signals, it seems that there is a delay between the CAN transmit and CAN receive, using two raspberry connected throgh CAN bus.

Any solution?