RECEIVE_CAN_MESSAGE

Read data from a CAN Bus connection. This block is used to read data from a CAN Bus connection. A connection to the CAN device must be established using the CAN_CONNECT block. Params: PCAN_address : str The CAN device address to connect to. timeout : int The timeout in seconds to wait for a message. Default is 10. raise_error : bool If True, an exception will be raised if no data is received. Default is True. Returns: Stateful : can.message.Message Return a can bus message

Python Code

from flojoy import flojoy, DataContainer, DeviceConnectionManager, Stateful
from typing import Optional
import can


@flojoy(deps={"python-can": "4.3.1"})
def RECEIVE_CAN_MESSAGE(
    CAN_address: str,
    timeout: int = 10,
    raise_error: bool = True,
    default: Optional[DataContainer] = None,
) -> Stateful:
    """Read data from a CAN Bus connection.

    This block is used to read data from a CAN Bus connection. A connection to the CAN device must be established using the CAN_CONNECT block.

    Parameters
    ----------
    PCAN_address : str
        The CAN device address to connect to.
    timeout : int
        The timeout in seconds to wait for a message. Default is 10.
    raise_error : bool
        If True, an exception will be raised if no data is received. Default is True.

    Returns
    -------
    Stateful : can.message.Message
        Return a can bus message
    """

    connection: can.interface.Bus = DeviceConnectionManager.get_connection(
        CAN_address
    ).get_handle()

    msg = connection.recv(timeout)

    if msg is None:
        if raise_error:
            raise Exception("No data received")
        else:
            return Stateful([])

    return Stateful([msg])

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Example

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Download this Flojoy App

This application demonstrates how to use multiple CAN blocks to connect to a PEAK-USB device and read messages from it. The PEAK-USB device is a USB-to-CAN interface that enables you to connect a computer to a CAN network. This device is used in this case to capture the messages of a particular sensor by filtering them directly at the kernel level, thus reducing the load on the CPU, and save those messages to a log file locally.

Once the app is done, the generated logs are exported to an S3 bucket to keep a record of the sensor’s data for further analysis.

To replicate this application, you must connect the PEAK-USB to your computer and install the required driver (refer to the PEAK_CONNECT blocks for more information on the necessary driver for your platform). Then, simply specify the PEAK-USB channel in the required blocks, and this Flojoy application will log the messages received by the device!

Detecting channels A valuable block is the PEAK_DETECT_AVAILABLE_DEVICE. This block allows you to display the devices using the PCAN interface that are connected to your computer.