# Channel

## openChannel()

canlib.canlib.openChannel(channel, flags=0, bitrate=None, data_bitrate=None)

  Open CAN channel

  Retrieves a `Channel` object for the given CANlib channel number using the supplied flags.

  Example usage:

      >>> bitrate = canlib.busparams.BusParamsTq(
      ... tq=40,
      ... phase1=5,
      ... phase2=6,
      ... sjw=4,
      ... prescaler=2,
      ... prop=28,
      ... )
      >>> data_bitrate = canlib.busparams.BusParamsTq(
      ... tq=40,
      ... phase1=31,
      ... phase2=8,
      ... sjw=2,
      ... prescaler=2,
      ... )
      >>> ch = canlib.openChannel(
      ... channel=0,
      ... flags=canlib.Open.CAN_FD,
      ... bitrate=bitrate,
      ... data_bitrate=data_bitrate,
      ... )

  Note

  If both `bitrate` and `data_bitrate` is given, both must be of the same type, i.e. either BusParamsTq or BITRATE flags. It is not supported to mix the two.

  Parameters

    - channel (`int`) – CANlib channel number

    - flags (`int`) – Flags, a combination of the `Open` flag values. Default is zero, i.e. no flags.

    - bitrate (`BusParamsTq` or `Bitrate` or `BitrateFD`) – The desired bitrate. If the bitrate is not a `BusParamsTq`, the predefined `Bitrate` values are used for classic CAN and `BitrateFD` values are used for CAN FD, e.g. `canlib.Bitrate.BITRATE_1M` and `canlib.BitrateFD.BITRATE_1M_80P`. For CAN FD, this parameter gives the arbitration bitrate.

    - data_bitrate (`BusParamsTq` or `BitrateFD`) – The desired data bitrate for CAN FD. If not `BusParamsTq` is given, the predefined `BitrateFD` values are used, e.g. `canlib.BitrateFD.BITRATE_500K_80p`. This parameter is only used when opening a CAN FD channel.

  Returns

    A `Channel` object created with channel and flags

  New in version 1.6: The bitrate and data_bitrate arguments was added.

  Changed in version 1.16: The bitrate and data_bitrate arguments now accept `BusParamsTq` objects.

  Changed in version 1.17: Added support for `Bitrate` and `BitrateFD` enumerations.

## ErrorCounters

class canlib.canlib.channel.ErrorCounters(tx, rx, overrun)

  Error counters returned by `Channel.read_error_counters`.

  property overrun

    Alias for field number 2

  property rx

    Alias for field number 1

  property tx

    Alias for field number 0

## Channel

class canlib.canlib.Channel(channel_number, flags=0)

  Helper class that represents a CANlib channel.

  This class wraps the canlib class and tries to implement a more Pythonic interface to CANlib.

  Channels are automatically closed on garbage collection, and can also be used as context managers in which case they close as soon as the context exits.

  Variables

    envvar (`EnvVar`) – Used to access t program environment variables

  allocate_periodic_objbuf(period_us, frame)

    Allocate a periodic object buffer (a.k.a. auto transmit buffer).

    Call `objbuf.Periodic.enable()` in order to start the periodic transmissions of the CAN frame.

    Parameters

      - period_us (`int`) – Interval in microseconds between each sent CAN frame.

      - frame (`Frame`) – The CAN frame to send.

    Returns

      `objbuf.Periodic` – A periodic object buffer.

    New in version 1.22.

  allocate_response_objbuf(filter, frame, rtr_only=False)

    Allocate autoresponse object buffer.

    Parameters

      - frame (`Frame`) – The CAN frame to send.

      - filter (`objbuf.MessageFilter`) – Messages not matching the filter is ignored.

      - rtr_only (`bool`) – If `True`, only trigger response on remote requests.

    Returns

      `objbuf.Response` – A response object buffer.

    New in version 1.22.

  announceIdentityEx(item, value)

    AnnounceIdentityEx function is used by certain OEM applications.

    New in version 1.17.

  bitrate_to_BusParamsTq(freq_a, freq_d=None)

    Calculate bus parameters based on predefined frequencies.

    This function uses the `Bitrate` and `BitrateFD` values to create bus parameters for use with the new bus parameter API.

    Parameters

      - freq_a (`Bitrate` or `BitrateFD`) – The bitrate for classic CAN channels specified as a `Bitrate`, or the arbitration bitrate for CAN FD channels specified as a `BitrateFD`.

      - freq_d (`BitrateFD`) – Data bitrate for CAN FD channels.

    Returns

      (`nominal`, `None`) for classic CAN, where `nominal` is a `BusParamsTq` object.

      (`nominal`, `data`) for CAN FD, where both `nominal` and `data` are `BusParamsTq` objects, representing the arbitration bitrate and the data bitrate, respectively.

    New in version 1.17.

  busOff()

    Takes the specified channel off-bus.

    Closes the channel associated with the handle. If no other threads are using the CAN circuit, it is taken off bus. The handle can not be used for further references to the channel.

  busOn()

    Takes the specified channel on-bus.

    If you are using multiple handles to the same physical channel, for example if you are implementing a multithreaded application, you must call busOn() once for each handle.

  canAccept(envelope, flag)

    Set acceptance filters mask or code.

    This routine sets the message acceptance filters on a CAN channel.

    Setting flag to `AcceptFilterFlag.NULL_MASK` (0) removes the filter.

    Note that not all CAN boards support different masks for standard and extended CAN identifiers.

    Parameters

      - envelope – The mask or code to set.

      - flag – Any of `AcceptFilterFlag`

  canSetAcceptanceFilter(code, mask, is_extended=False)

    Set message acceptance filter.

    This routine sets the message acceptance filters on a CAN channel. The message is accepted `if id AND mask == code` (this is actually imlepemented as `if ((code XOR id) AND mask) == 0`).

    Using standard 11-bit CAN identifiers and setting

    - mask = 0x7f0,

    - code = 0x080

    accepts CAN messages with standard id 0x080 to 0x08f.

    Setting the mask to canFILTER_NULL_MASK (0) removes the filter.

    Note that not all CAN boards support different masks for standard and extended CAN identifiers.

    Parameters

      - mask (`int`) – A bit mask that indicates relevant bits with ‘1’.

      - code (`int`) – The expected state of the masked bits.

      - is_extended (`bool`) – If `True`, both mask and code applies to 29-bit CAN identifiers.

  property channel_data

    `canGetHandleData` helper object for this channel

    See the documentation for `ChannelData`/`HandleData` for how it can be used to perform all functionality of the C function `canGetHandleData`.

    New in version 1.13.

    Type

      `HandleData`

  close()

    Close CANlib channel

    Closes the channel associated with the handle. If no other threads are using the CAN circuit, it is taken off bus.

    Note

    It is normally not necessary to call this function directly, as the internal handle is automatically closed when the `Channel` object is garbage collected.

  device()

    Get a Device object from the current channel

    Returns

      `Device` – Device used by this channel,

    New in version 1.16.

  fileCopyFromDevice(deviceFileName, hostFileName=None)

    Copy an arbitrary file from the device to the host.

    Parameters

      - deviceFileName (`str`) – The device file name.

      - hostFileName (`str`, optional) – The target host file name. Defaults to deviceFileName.

  fileCopyToDevice(hostFileName, deviceFileName=None)

    Copy an arbitrary file from the host to the () isdevice.

    The filename must adhere to the FAT ‘8.3’ naming standard, max 8 characters - a dot - max 3 characters.

    Parameters

      - hostFileName (`str`) – The target host file name.

      - deviceFileName (`str`, optional) – The device file name. Defaults to the same as hostFileName.

  fileDelete(deviceFileName)

    Delete file from device.

  fileDiskFormat()

    Format the disk on the device, not supported by all devices.

    New in version 1.11.

  fileGetCount()

    Get the number of files on the device.

    Returns

      `int` – The number of files.

  fileGetName(fileNo)

    Get the name of the file with the supplied number.

    Parameters

      fileNo (`int`) – The number of the file.

    Returns

      `str` – The name of the file.

  flashLeds(action, timeout_ms)

    Turn Leds on or off.

    Parameters

      - action (`int`) – One of `LEDAction`, defining which LED to turn on or off.

      - timeout_ms (`int`) – Specifies the time, in milliseconds, during which the action is to be carried out. When the timeout expires, the LED(s) will return to its ordinary function.

  free_objbuf()

    Free all allocated object buffers.

    Free all object buffers allocated via `allocate_periodic_objbuf()` or `allocate_response_objbuf()`.

    New in version 1.22.

  getBusOutputControl()

    Get driver type

    This function retrieves the current CAN controller driver type. This corresponds loosely to the bus output control register in the CAN controller, hence the name of this function.

    Note

    Not all CAN driver types are supported on all cards.

    Returns

      drivertype (`canlib.Driver`) – Driver type to set.

    New in version 1.11.

  getBusParams()

    Get bus timing parameters for classic CAN.

    This function retrieves the current bus parameters for the specified channel.

    Returns: A tuple containing:

      freq: Bitrate in bit/s.

      tseg1: Number of quanta from but not including the Sync Segment to the sampling point.

      tseg2: Number of quanta from the sampling point to the end of the bit.

      sjw: The Synchronization Jump Width, can be 1, 2, 3, or 4.

      noSamp: The number of sampling points, only 1 is supported.

      syncmode: Unsupported, always read as zero.

  getBusParamsFd()

    Get bus timing parameters for BRS in CAN FD.

    This function retrieves the bus current timing parameters used in BRS (Bit rate switch) mode for the current CANlib channel.

    The library provides default values for tseg1_brs, tseg2_brs and sjw_brs when freq is a `BitrateFD` value.

    If freq is any other value, no default values are supplied by the library.

    For finding out if a channel was opened as CAN FD, use `is_can_fd()`

    Returns: A tuple containing:

      freq_brs: Bitrate in bit/s.

      tseg1_brs: Number of quanta from (but not including) the Sync Segment to the sampling point.

      tseg2_brs: Number of quanta from the sampling point to the end of the bit.

      sjw_brs: The Synchronization Jump Width.

  getChannelData_CardNumber()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.card_number`

  getChannelData_Chan_No_On_Card()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.chan_no_on_card`

  getChannelData_Cust_Name()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.custom_name`

  getChannelData_DriverName()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.driver_name`

  getChannelData_EAN()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.card_upc_no`

  getChannelData_EAN_short()
  getChannelData_Firmware()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.card_firmware_rev`

  getChannelData_Name()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.device_name`

  getChannelData_Serial()

    Deprecated function

    Deprecated since version 1.5: Use `ChannelData`; `ChannelData.card_serial_no`

  get_bus_params_tq()

    Get bus timing parameters, in time quanta

    This function retrieves the current bus parameters for the specified channel. Only the returned `nominal` parameter is valid when classic CAN is in use.

    Returns: A `tuple` containing:

    > nominal: (`BusParamsTq`) Nominal bus timing parameters, also used in classic CAN.

    > data: (`BusParamsTq`) Bus timing parameters for data rate in CAN FD.

    New in version 1.16.

  get_bus_statistics()

    Return bus statistics.

    Returns

      `structures.CanBusStatistics`

  get_io_pin(index)

    Return I/O pin using index

    Returns

      `iopin.IoPin` – io pin object for index (Any of `iopin.AnalogIn`, `iopin.DigitalOut` etc)

    New in version 1.8.

  ioCtl_flush_rx_buffer()

    Deprecated function

    Deprecated since version 1.5: Use `IOControl`; `Channel.iocontrol.flush_rx_buffer()`.

  ioCtl_get_report_access_errors()

    Deprecated function

    Deprecated since version 1.5: Use `IOControl`; `Channel.iocontrol.report_access_errors`

  ioCtl_set_report_access_errors(on=0)

    Deprecated function

    Deprecated since version 1.5: Use `IOControl`; `Channel.iocontrol.report_access_errors = True`

  ioCtl_set_timer_scale(scale)

    Deprecated function

    Deprecated since version 1.5: Use `IOControl`; `Channel.iocontrol.timer_scale = scale`

  io_confirm_config()

    Confirm current I/O configuration

    It is required to confirm a configuration by calling this function before accessing any I/O pins value.

    New in version 1.8.

  io_pins()

    Generator that returns all I/O pins one by one

    Returns object depending on pin type and direction: `iopin.AnalogIn`, `iopin.AnalogOut`, `iopin.DigitalIn`, `iopin.DigitalOut` or `iopin.Relay`.

    New in version 1.8.

  property iocontrol

    `canIoCtl` helper object for this channel

    See the documentation for `IOControl` for how it can be used to perform all functionality of the C function `canIoCtl`.

    Example usage:

        >>> from canlib import canlib
        >>> ch = canlib.openChannel(channel=0)
        >>> ch.iocontrol.timer_scale
        1000
        >>> ch.iocontrol.local_txecho = False

    Type

      `IOControl`

  is_can_fd()

    Return `True` if the channel has been opened with the `CAN_FD` or `CAN_FD_NONISO` flags.

    Returns

      `True` if CAN FD, `False` otherwise.

  kvDeviceGetMode()

    Read the current device’s mode.

    Note

    The mode is device specific, which means that not all modes are implemented in all products.

    Returns

      `int` – One of `DeviceMode`, indicating which mode is in use.

  kvDeviceSetMode(mode)

    Set the current device’s mode.

    Note

    The mode is device specific, which means that not all modes are implemented in all products.

    Parameters

      mode (`int`) – One of `DeviceMode`, defining which mode to use.

  number_of_io_pins()

    Return the total number of available I/O pins

    New in version 1.8.

  read(timeout=0)

    Read a CAN message and metadata.

    Reads a message from the receive buffer. If no message is available, the function waits until a message arrives or a timeout occurs.

    The unit of the returned `Frame.timestamp` is configurable using `Channel.iocontrol.timer_scale`, default is 1 ms.

    Note

    If you are using the same channel via multiple handles, the default behaviour is that the different handles will “hear” each other just as if each handle referred to a channel of its own. If you open, say, channel 0 from thread A and thread B and then send a message from thread A, it will be “received” by thread B.

    This behaviour can be changed by setting `local_txecho` to `False` (using `IOControl`):

        >>> from canlib import canlib
        >>> ch = canlib.openChannel(channel=0)
        >>> ch.iocontrol.local_txecho = False

    Parameters

      timeout (`int`) – Timeout in milliseconds, -1 gives an infinite timeout.

    Returns

      `canlib.Frame`

    Raises

      CanNoMsg – No CAN message is currently available.

  readDeviceCustomerData(userNumber=100, itemNumber=0)

    Read customer data stored in device

  readSpecificSkip(id_)

    Read a message with specified identifier

    Reads a message with a specified identifier from the receive buffer. Any preceding message not matching the specified identifier will be removed in the receive buffer. If no message with the specified identifier is available, the function returns immediately with an error code.

    The unit of the returned `Frame.timestamp` is configurable using `Channel.iocontrol.timer_scale`, default is 1 ms.

    Returns

      `canlib.Frame`

  readStatus()

    Return status for the current channel

    Returns the latest status reported by the hardware in a combination of the flags `Stat` (bus on/error passive + status etc).

    Returns

      `canlib.canlib.Stat`

  readSyncSpecific(id_, timeout=0)

    Wait until the receive queue contains a message with the specified id

  readTimer()

    Read the hardware clock on the specified device

    Returns the time value.

  read_error_counters()

    Read the error counters of the CAN controller

    Returns the latest known values of the error counters in the specified circuit. If the error counters change values precisely when `read_error_counters` is called, it may not be reflected in the returned result.

    Use `clear_error_counters` via `Channel.iocontrol` to clear the counters.

    Returns

      The returned tuple is a `(rx, tx, overrun)` named tuple of –

      1. `rx` (`int`): Receive error counter

      2. `tx` (`int`): Transmit error counter

      3. `overrun` (`int`): Number of overrun errors.

    New in version 1.11.

  requestChipStatus()

    Request chip status messages

    Requests that the hardware report the chip status (bus on/error passive status etc.) to the driver. The chip status can later be retrieved using `canlib.Channel.readStatus`.

    Note

    The `requestChipStatus` function is asynchronous, that is, it completes before the answer is returned from the hardware. The time between a call to `requestChipStatus` and the point in time where the chip status is actually available via a call to `Channel.readStatus` is not defined. The `Channel.readStatus` always returns the latest data reported by the hardware.

  scriptEnvvarClose(envHandle)

    Low level function to close an Envvar

    This should normally not be used directly, instead opening and closing of an envvar is automatically done when accessing via the `EnvVar` class through `Channel.envvar`

  scriptEnvvarGetData(envHandle, envSize)
  scriptEnvvarGetFloat(envHandle)

    Low level function to read an Envvar of type float

    This should normally not be used directly, instead set and get the value of an envvar using the `EnvVar` class through `Channel.envvar`

  scriptEnvvarGetInt(envHandle)

    Low level function to read an Envvar of type int

    This should normally not be used directly, instead set and get the value of an envvar using the `EnvVar` class through `Channel.envvar`

  scriptEnvvarOpen(name)

    Low level function to open an Envvar

    This should normally not be used directly, instead opening and closing of an envvar is automatically done when accessing via the `EnvVar` class through `Channel.envvar`

  scriptEnvvarSetData(envHandle, value, envSize)
  scriptEnvvarSetFloat(envHandle, value)

    Low level function to set an Envvar of type float

    This should normally not be used directly, instead set and get the value of an envvar using the `EnvVar` class through `Channel.envvar`

  scriptEnvvarSetInt(envHandle, value)

    Low level function to set an Envvar of type int

    This should normally not be used directly, instead set and get the value of an envvar using the `EnvVar` class through `Channel.envvar`

  scriptGetText()

    Read text from subscribed script slots

    Text-subscriptions must first be set up with `Channel.scriptRequestText`.

    Returns

      `ScriptText`

    Raises

      CanNoMsg – No more text is currently available.

    New in version 1.7.

  scriptLoadFile(slot, filePathOnPC)

    Load compiled script file from host(PC)

    Loads a compiled script file (.txe) stored on the host (PC) into a script slot on the device. The scripts default channel will be the same channel used when this Channel object was created.

    Parameters

      - slot (`int`) – slot containing the running script we want to stop.

      - filePathOnPC (`str`) – Path to compiled script (.txe) to load.

  scriptLoadFileOnDevice(slot, localFile)

    Load compiled, locally stored, script file

    Loads a compiled script file (.txe) stored locally on the device (SD card) into a script slot on the device. The scripts default channel will be the same channel used when this Channel object was created.

    Parameters

      - slot (`int`) – slot containing the running script we want to stop.

      - localFile (`str`) – Name of compiled script (.txe) to load.

  scriptRequestText(slot, request=ScriptRequest.SUBSCRIBE)

    Set up a printf subscription to a selected script slot

    Parameters

      - slot (`int`) – The script slot to subscribe/unsubscribe from.

      - request (`ScriptRequest`) – Whether to subscribe or unsubscribe.

    Text printed with `printf()` by a t-program that you are subscribed to is saved and can be retrieved with `Channel.scriptGetText`.

    New in version 1.7.

  scriptSendEvent(slotNo=0, eventType=1, eventNo=None, data=0)

    Send specified event to specified t script

    Send an event with given type, event number, and associated data to a script running in a specific slot.

  scriptStart(slot)

    Start previously loaded script in specified slot

  scriptStatus(slot)

    Retreives t program status for selected slot

    Parameters

      slot (`int`) – Slot number to be queried

    Returns

      `canlib.ScriptStatus`

    New in version 1.6.

  scriptStop(slot, mode=ScriptStop.NORMAL)

    Stop script running in specified slot

    Parameters

      - slot (`int`) – slot containing the running script we want to stop.

      - mode (`canlib.ScriptStop`) – Default mode is `canlib.ScriptStop.NORMAL`.

  scriptUnload(slot)

    Unload previously stopped script in specified slot

  script_envvar_get_data(envHandle, len, start=0)

    Low level function to read a slice of an Envvar of type char

    This should normally not be used directly, instead set and get the value of an envvar using the `EnvVar` class through `Channel.envvar`

    New in version 1.10.

  script_envvar_set_data(envHandle, value, len, start=0)

    Low level function to write a slice of an Envvar of type char

    This should normally not be used directly, instead set and get the value of an envvar using the `EnvVar` class through `Channel.envvar`

    `value` needs to be a bytes-like object or list

    New in version 1.10.

  setBusOutputControl(drivertype=Driver.NORMAL)

    Set driver type

    This function sets the driver type for a CAN controller to e.g. silent mode. This corresponds loosely to the bus output control register in the CAN controller, hence the name of this function.

    Note

    Not all CAN driver types are supported on all cards.

    Parameters

      drivertype (`canlib.Driver`) – Driver type to set.

  setBusParams(freq, tseg1=0, tseg2=0, sjw=0, noSamp=0, syncmode=0)

    Set bus timing parameters for classic CAN

    This function sets the bus timing parameters for the specified CAN controller.

    The library provides default values for tseg1, tseg2, sjw and noSamp when freq is a `Bitrate`, e.g. `Bitrate.BITRATE_1M`.

    If freq is any other value, no default values are supplied by the library.

    If you are using multiple handles to the same physical channel, for example if you are implementing a multithreaded application, you must call `busOn()` once for each handle. The same applies to `busOff()` - the physical channel will not go off bus until the last handle to the channel goes off bus.

    Parameters

      - freq – Bitrate in bit/s.

      - tseg1 – Number of quanta from (but not including) the Sync Segment to the sampling point.

      - tseg2 – Number of quanta from the sampling point to the end of the bit.

      - sjw – The Synchronization Jump Width, can be 1, 2, 3, or 4.

      - nosamp – The number of sampling points, only 1 is supported.

      - syncMode – Unsupported and ignored.

    Changed in version 1.17: Now accepts `Bitrate` enumerations.

  setBusParamsFd(freq_brs, tseg1_brs=0, tseg2_brs=0, sjw_brs=0)

    Set bus timing parameters for BRS in CAN FD

    This function sets the bus timing parameters used in BRS (Bit rate switch) mode for the current CANlib channel.

    The library provides default values for tseg1_brs, tseg2_brs and sjw_brs when freq is a `BitrateFD` value, e.g. `BitrateFD.BITRATE_1M_80P`.

    If freq is any other value, no default values are supplied by the library.

    For finding out if a channel was opened as CAN FD, use `is_can_fd()`

    Parameters

      - freq_brs – Bitrate in bit/s.

      - tseg1_brs – Number of quanta from (but not including) the Sync Segment to the sampling point.

      - tseg2_brs – Number of quanta from the sampling point to the end of the bit.

      - sjw_brs – The Synchronization Jump Width.

    Changed in version 1.17: Now accepts `BitrateFD` enumerations.

  set_bus_params_tq(nominal, data=None)

    Set bus timing parameters, using time quanta

    This function sets the bus timing parameters for the specified CAN controller. When setting bus parameters for CAN FD, both `nominal` and `data` must be given.

    If you are using multiple handles to the same physical channel, for example if you are implementing a multithreaded application, you must call `busOff()` once for each handle. The physical channel will not go off bus until the last handle to the channel goes off bus. The same applies to `busOn()`.

    Parameters

      - nominal (`BusParamsTq`) – Nominal Bus timing parameters, also used for classic CAN

      - data (`BusParamsTq`) – Bus timing parameters for data rate in CAN FD.

    New in version 1.16.

  set_callback(function, event, context=None)

    Register callback function

    This will register a callback function which is called when certain events occur. You can register at most one callback function per handle at any time.

    Note:

    The callback function is called in the context of a high-priority thread created by CANlib. You should take precaution not to do any time consuming tasks in the callback.

    Small example of usage:

        # Declare callback function
        def callback_func(hnd, context, event):
            event = canlib.Notify(event)

            # The nonlocal statement causes the listed identifiers to refer
            # to previously bound variables in the nearest enclosing scope
            # excluding globals.
            nonlocal callback_has_been_called
            print("Callback called, context:{}, event:{!r}".format(context, event))
            # Notify the main program by setting the flag
            callback_has_been_called = True

        # setup communication variable and callback
        callback_has_been_called = False
        callback = canlib.dll.KVCALLBACK_T(callback_func)

        with canlib.openChannel(0) as ch:
        ch.set_callback(callback, context=121, event=canlib.Notify.BUSONOFF)
        # trigger the callback
        ch.busOn()
        # do something else
        time.sleep(0.5)
        # Verify that the callback was triggered
        assert callback_has_been_called

    Note:

    It is very important to make sure that you keep a reference to the callback type (`callback` in the sample above) for as long as any C library might call it. If it gets deleted by the garbage collector, calling it from C is likely to either cause a segfault or maybe even interpret random memory as machine language.

    Parameters

      - function (`KVCALLBACK_T`) – A ctypes wrapped Python function

      - event (`Notify`) – A combination of flags to indicate what events to trigger on

    New in version 1.7.

  write(frame=None, *args, **kwargs)

    Send a CAN message.

    This function sends a Frame object as a CAN message. Note that the message has been queued for transmission when this calls return. It has not necessarily been sent.

    Note

    If you are using the same channel via multiple handles, the default behaviour is that the different handles will “hear” each other just as if each handle referred to a channel of its own. If you open, say, channel 0 from thread A and thread B and then send a message from thread A, it will be “received” by thread B.

    This behaviour can be changed by setting `local_txecho` to `False` (using `IOControl`):

        >>> from canlib import canlib
        >>> ch = canlib.openChannel(channel=0)
        >>> ch.iocontrol.local_txecho = False

    Also see `Channel.write_raw` for sending messages without constructing `canlib.Frame` objects.

    Deprecated since version 1.5: Sending the `canlib.Frame` contents as separate arguments; this functionality has been taken over by `write_raw`.

    Parameters

      frame (`canlib.Frame`)

  writeSync(timeout)

    Wait for queued messages to be sent

    Waits until all CAN messages for the specified handle are sent, or the timeout period expires.

    Parameters

      timeout (`int`) – The timeout in milliseconds, `None` or `0xFFFFFFFF` for an infinite timeout.

  writeWait(frame, timeout, *args, **kwargs)

    Sends a CAN message and waits for it to be sent.

    This function sends a CAN message. It returns when the message is sent, or the timeout expires. This is a convenience function that combines write() and writeSync().

    Deprecated since version 1.5: Sending the `Frame` contents as separate arguments; this functionality has been taken over by `writeWait_raw`.

    Parameters

      - frame (`canlib.Frame`) – Frame containing the CAN data to be sent

      - timeout (`int`) – The timeout, in milliseconds. 0xFFFFFFFF gives an infinite timeout.

  writeWait_raw(id_, msg, flag=0, dlc=0, timeout=0)

    Sends a CAN message and waits for it to be sent.

    This function sends a CAN message. It returns when the message is sent, or the timeout expires. This is a convenience function that combines write() and writeSync().

    Parameters

      - id_ – The identifier of the CAN message to send.

      - msg – An array or bytearray of the message data

      - flag – A combination of `canlib.canlib.MessageFlag`. Use this parameter e.g. to send extended (29-bit) frames.

      - dlc – The length of the message in bytes. For Classic CAN dlc can be at most 8, unless `canlib.canlib.Open.ACCEPT_LARGE_DLC` is used. For CAN FD dlc can be one of the following 0-8, 12, 16, 20, 24, 32, 48, 64. Optional, if omitted, dlc is calculated from the msg array.

      - timeout – The timeout, in milliseconds. 0xFFFFFFFF gives an infinite timeout.

  write_raw(id_, msg, flag=0, dlc=None)

    Send a CAN message

    See docstring of `Channel.write` for general information about sending CAN messages.

    The variable name id (as used by canlib) is a built-in function in Python, so the name `id_` is used instead.

    Parameters

      - id_ – The identifier of the CAN message to send.

      - msg – An array or bytearray of the message data

      - flag – A combination of `MessageFlag`. Use this parameter e.g. to send extended (29-bit) frames.

      - dlc – The length of the message in bytes. For Classic CAN dlc can be at most 8, unless `Open.ACCEPT_LARGE_DLC` is used. For CAN FD dlc can be one of the following 0-8, 12, 16, 20, 24, 32, 48, 64. Optional, if omitted, dlc is calculated from the msg array.

## CanBusStatistics

class canlib.canlib.structures.CanBusStatistics

  Result from reading bus statistics using `canlib.canlib.Channel.get_bus_statistics`.

  Variables

    - busLoad (`int`) – The bus load, expressed as an integer in the interval 0 - 10000 representing 0.00% - 100.00% bus load.

    - errFrame (`int`) – Number of error frames.

    - extData (`int`) – Number of received extended (29-bit identifiers) data frames.

    - extRemote (`int`) – Number of received extended (29-bit identifiers) remote frames.

    - overruns (`int`) – The number of overruns detected by the hardware, firmware or driver.

    - stdData (`int`) – Number of received standard (11-bit identifiers) data frames.

    - stdRemote (`int`) – Number of received standard (11-bit identifiers) remote frames.