SET_CAN_BUS_FILTER

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Attach a message filter to a CAN bus connection. Setup a message filtering can be set up for each bus. The binary operation is as follow: <received_can_id> & can_mask == can_id & can_mask All messages that match at least one filter are returned. Where the interface supports it, this is carried out in the hardware or kernel layer - not in Python. A connection to the device is required. Use a CAN_CONNECT block to connect to a CAN device. Params: CAN_address : str The CAN bus address to attach the filter to. can_id : int The ID of the message to filter. can_mask : int Apply a binary mask to the ID and can_id. extended : bool If true, only matches messages where <received_is_extended> == extended. Returns: out : DataContainer Optional: None

Python Code

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


@flojoy(deps={"python-can": "4.3.1"})
def SET_CAN_BUS_FILTER(
    CAN_address: str,
    can_id: int = 0x0000001,
    can_mask: int = 0xFFFFFFFF,
    extended: bool = False,
    default: Optional[DataContainer] = None,
) -> Optional[DataContainer]:
    """Attach a message filter to a CAN bus connection.

    Setup a message filtering can be set up for each bus.
    The binary operation is as follow: <received_can_id> & can_mask == can_id & can_mask
    All messages that match at least one filter are returned.

    Where the interface supports it, this is carried out in the hardware or kernel layer - not in Python.
    A connection to the device is required. Use a CAN_CONNECT block to connect to a CAN device.

    Parameters
    ----------
    CAN_address : str
        The CAN bus address to attach the filter to.
    can_id : int
        The ID of the message to filter.
    can_mask : int
        Apply a binary mask to the ID and can_id.
    extended : bool
        If true, only matches messages where <received_is_extended> == extended.

    Returns
    -------
    DataContainer
        Optional: None
    """
    connection: can.interface.Bus = DeviceConnectionManager.get_connection(
        CAN_address
    ).get_handle()

    connection.set_filters(
        [{"can_id": can_id, "can_mask": can_mask, "extended": extended}]
    )

    return None

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Example App

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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.