CAN over Serial / SLCAN#

A text based interface: compatible to slcan-interfaces (slcan ASCII protocol) should also support LAWICEL direct. These interfaces can also be used with socketcan and slcand with Linux. This driver directly uses either the local or remote serial port, it makes slcan-compatible interfaces usable with Windows also. Remote serial ports will be specified via special URL. Both raw TCP sockets as also RFC2217 ports are supported.

Usage: use port or URL[@baurate] to open the device. For example use /dev/ttyUSB0@115200 or COM4@9600 for local serial ports and socket://192.168.254.254:5000 or rfc2217://192.168.254.254:5000 for remote ports.

Supported devices#

Todo

Document this.

Bus#

class can.interfaces.slcan.slcanBus(channel, ttyBaudrate=115200, bitrate=None, btr=None, sleep_after_open=2, rtscts=False, **kwargs)[source]#

slcan interface

Parameters

channel (str) – port of underlying serial or usb device (e.g. /dev/ttyUSB0, COM8, …) Must not be empty. Can also end with @115200 (or similarly) to specify the baudrate.
ttyBaudrate (int) – baudrate of underlying serial or usb device (Ignored if set via the channel parameter)
bitrate (Optional[int]) – Bitrate in bit/s
btr (Optional[str]) – BTR register value to set custom can speed
poll_interval – Poll interval in seconds when reading messages
sleep_after_open (float) – Time to wait in seconds after opening serial connection
rtscts (bool) – turn hardware handshake (RTS/CTS) on and off
kwargs (Any) –

Raises

ValueError – if both bitrate and btr are set or the channel is invalid
CanInterfaceNotImplementedError – if the serial module is missing
CanInitializationError – if the underlying serial connection could not be established

Return type

None

get_serial_number(timeout)[source]#

Get serial number of the slcan interface.

Parameters: timeout (Optional[float]) – seconds to wait for serial number or None to wait indefinitely
Returns: None on timeout or a str object.
Return type: Optional[str]

get_version(timeout)[source]#

Get HW and SW version of the slcan interface.

Parameters: timeout (Optional[float]) – seconds to wait for version or None to wait indefinitely
Returns: tuple (hw_version, sw_version) WHERE int hw_version is the hardware version or None on timeout int sw_version is the software version or None on timeout
Return type: Tuple[Optional[int], Optional[int]]

send(msg, timeout=None)[source]#

Transmit a message to the CAN bus.

Override this method to enable the transmit path.

Parameters

msg (Message) – A message object.
timeout (Optional[float]) – If > 0, wait up to this many seconds for message to be ACK’ed or for transmit queue to be ready depending on driver implementation. If timeout is exceeded, an exception will be raised. Might not be supported by all interfaces. None blocks indefinitely.

Raises

CanOperationError – If an error occurred while sending

Return type

None

set_bitrate(bitrate)[source]#

Parameters: bitrate (int) – Bitrate in bit/s
Raises: ValueError – if bitrate is not among the possible values
Return type: None

set_bitrate_reg(btr)[source]#

Parameters: btr (str) – BTR register value to set custom can speed
Return type: None

shutdown()[source]#

Called to carry out any interface specific cleanup required in shutting down a bus.

Return type: None

Internals#

Todo

Document the internals of slcan interface.