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, tty_baudrate=115200, bitrate=None, timing=None, sleep_after_open=2, rtscts=False, listen_only=False, timeout=0.001, **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.tty_baudrate (int) – baudrate of underlying serial or usb device (Ignored if set via the
channel
parameter)bitrate (int | None) – Bitrate in bit/s
timing (BitTiming | BitTimingFd | None) – Optional
BitTiming
instance to use for custom bit timing setting. If this argument is set then it overrides the bitrate and btr arguments. The f_clock value of the timing instance must be set to 8_000_000 (8MHz) for standard CAN. CAN FD and theBitTimingFd
class are not supported.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
listen_only (bool) – If True, open interface/channel in listen mode with
L
command. Otherwise, the (default)O
command is still used. Seeopen
method.timeout (float) – Timeout for the serial or usb device in seconds (default 0.001)
kwargs (Any)
- Raises:
ValueError – if both
bitrate
andbtr
are set or the channel is invalidCanInterfaceNotImplementedError – if the serial module is missing
CanInitializationError – if the underlying serial connection could not be established
- 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 (float | None) – 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
Internals¶
Todo
Document the internals of slcan interface.