- class pycyphal.transport.can.media.pythoncan.PythonCANMedia(iface_name: str, bitrate: Union[int, Tuple[int, int]], mtu: Optional[int] = None, *, loop: Optional[asyncio.events.AbstractEventLoop] = None)
Media interface adapter for Python-CAN. It is designed to be usable with all host platforms supported by Python-CAN (GNU/Linux, Windows, macOS). Please refer to the Python-CAN documentation for information about supported CAN hardware, its configuration, and how to install the dependencies properly.
This media interface supports both Classic CAN and CAN FD. The selection logic is documented below.
Python-CAN supports hardware loopback and timestamping only for some of the interfaces. This has to be manually specified in PythonCANBusOptions for supported hardware. Both are disabled by default, but can be enabled if it is verified that hardware in question supports either or both options. For best compatibility, consider using the non-python-can SocketCAN media driver instead.
Here is a basic usage example based on the Yakut CLI tool. Suppose that there are two interconnected CAN bus adapters connected to the host computer: one SLCAN-based, the other is PCAN USB. Launch Yakut to listen for messages using the SLCAN adapter (only one at a time):
export UAVCAN__CAN__IFACE="slcan:/dev/serial/by-id/usb-Zubax_Robotics_Zubax_Babel_1B003D00145130365030332000000000-if00" export UAVCAN__CAN__BITRATE='1000000 1000000' export UAVCAN__CAN__MTU=8 yakut sub 33:uavcan.si.unit.voltage.scalar
- __init__(iface_name: str, bitrate: Union[int, Tuple[int, int]], mtu: Optional[int] = None, *, loop: Optional[asyncio.events.AbstractEventLoop] = None) None
Interface name consisting of Python-CAN interface module name and its channel, separated with a colon. Supported interfaces are documented below. The semantics of the channel name are described in the documentation for Python-CAN.
socketcanis implemented by
can.interfaces.socketcan.SocketcanBus. The bit rate values are only used to select Classic/FD mode. It is not possible to configure the actual CAN bit rate using this API. Example:
kvaseris implemented by
slcanis implemented by
can.interfaces.slcan.slcanBus. Only Classic CAN is supported. The serial port settings are fixed at 8N1, but baudrate can be optionally specified with
virtualis described in https://python-can.readthedocs.io/en/master/interfaces/virtual.html. The channel name should be empty. Example:
usb2canis described in https://python-can.readthedocs.io/en/stable/interfaces/usb2can.html. Example:
canalystiiis described in https://python-can.readthedocs.io/en/stable/interfaces/canalystii.html. You need to download CANalyst library for python-can package or you can install python-can by:
pip3 install git+https://github.com/Cherish-Gww/python-can.git@add_canalystii_soMore info: https://github.com/OpenCyphal/pycyphal/issues/178#issuecomment-912497882 Example:
seeedstudiois described in https://python-can.readthedocs.io/en/stable/interfaces/seeedstudio.html. Example:
gs_usbis implemented by
can.interfaces.gs_usb.GsUsbBus. Channel name is an integer, refering to the device index in a system. Example:
gs_usb:0Note: this interface currently requires unreleased python-can version from git.
Bit rate value in bauds; either a single integer or a tuple:
A single integer selects Classic CAN.
A tuple of two selects CAN FD, where the first integer defines the arbitration (nominal) bit rate and the second one defines the data phase bit rate.
If MTU (see below) is given and is greater than 8 bytes, CAN FD is used regardless of the above.
An MTU of 8 bytes and a tuple of two identical bit rates selects Classic CAN.
The maximum CAN data field size in bytes. If provided, this value must belong to
Media.VALID_MTU_SET. If not provided, the default is determined as follows:
If bitrate is a single integer: classic CAN is assumed, MTU defaults to 8 bytes.
If bitrate is two integers: CAN FD is assumed, MTU defaults to 64 bytes.
loop – Deprecated.
InvalidMediaConfigurationErrorif the specified media instance could not be constructed, the interface name is unknown, or if the underlying library raised a
Use virtual bus with various bit rate and FD configurations:
>>> media = PythonCANMedia('virtual:', 500_000) >>> media.is_fd, media.mtu (False, 8) >>> media = PythonCANMedia('virtual:', (500_000, 2_000_000)) >>> media.is_fd, media.mtu (True, 64) >>> media = PythonCANMedia('virtual:', 1_000_000, 16) >>> media.is_fd, media.mtu (True, 16)
Use PCAN-USB channel 1 in FD mode with nominal bitrate 500 kbit/s, data bitrate 2 Mbit/s, MTU 64 bytes:
PythonCANMedia('pcan:PCAN_USBBUS1', (500_000, 2_000_000))
Use Kvaser channel 0 in classic mode with bitrate 500k:
Use CANalyst-II channel 0 in classic mode with bitrate 500k:
- property number_of_acceptance_filters: int
The value is currently fixed at 1 for all interfaces. TODO: obtain the number of acceptance filters from Python-CAN.
- property is_fd: bool
Introspection helper. The value is True if the underlying interface operates in CAN FD mode.
- start(handler: Callable[[Sequence[Tuple[pycyphal.transport._timestamp.Timestamp, pycyphal.transport.can.media._frame.Envelope]]], None], no_automatic_retransmission: bool) None
- configure_acceptance_filters(configuration: Sequence[pycyphal.transport.can.media._filter.FilterConfiguration]) None
- async send(frames: Iterable[pycyphal.transport.can.media._frame.Envelope], monotonic_deadline: float) int