uds.can.frame

Implementation for CAN frame fields that are influenced by UDS.

Handlers for CAN Frame fields:

CAN Identifier
DLC
Data

Attributes

DEFAULT_FILLER_BYTE

Default value of Filler Byte.

Classes

`CanVersion`	Versions of CAN bus.
`CanIdHandler`	Helper class that provides utilities for CAN Identifier field.
`CanDlcHandler`	Helper class that provides utilities for CAN Data Length Code field.

Module Contents

uds.can.frame.DEFAULT_FILLER_BYTE: int = 204: Default value of Filler Byte. Filler Bytes are used for CAN Frame Data Padding. .. note:: The value is specified by ISO 15765-2:2016 (chapter 10.4.2.1).

class uds.can.frame.CanVersion[source]

Bases: uds.utilities.ValidatedEnum

Inheritance diagram of uds.can.frame.CanVersion

Versions of CAN bus.

CLASSIC_CAN: CanVersion = 'Classic CAN': Classic CAN 2.0

CAN_FD: CanVersion = 'CAN FD': CAN FD

class uds.can.frame.CanIdHandler[source]

Helper class that provides utilities for CAN Identifier field.

CAN Identifier (CAN ID) is a CAN frame field that informs about a sender and a content of CAN frames.

CAN bus supports two formats of CAN ID:

Standard (11-bit Identifier)
Extended (29-bit Identifier)

MIN_STANDARD_VALUE: int = 0: Minimum value of Standard (11-bit) CAN ID.

MAX_STANDARD_VALUE: int = 2047: Maximum value of Standard (11-bit) CAN ID.

MIN_EXTENDED_VALUE: int = 2048: Minimum value of Extended (29-bit) CAN ID.

MAX_EXTENDED_VALUE: int = 536870911: Maximum value of Extended (29-bit) CAN ID.

ADDRESSING_MASK: int = 67043328: CAN ID mask for bits enforced by SAE J1939 (Normal Fixed of Mixed 29bit addressing formats).

NORMAL_FIXED_PHYSICAL_ADDRESSING_MASKED_VALUE: int = 14286848: Masked value of physically addressed CAN ID in Normal Fixed Addressing format.

NORMAL_FIXED_FUNCTIONAL_ADDRESSING_MASKED_VALUE: int = 14352384: Masked value of functionally addressed CAN ID in Normal Fixed Addressing format.

MIXED_29BIT_PHYSICAL_ADDRESSING_MASKED_VALUE: int = 13500416: Masked value of physically addressed CAN ID in Mixed 29-bit Addressing format.

MIXED_29BIT_FUNCTIONAL_ADDRESSING_MASKED_VALUE: int = 13434880: Masked value of functionally addressed CAN ID in Mixed 29-bit Addressing format.

TARGET_ADDRESS_BIT_OFFSET: int = 8: Bit offset of Target Address parameter in CAN Identifier.

SOURCE_ADDRESS_BIT_OFFSET: int = 0: Bit offset of Source Address parameter.

PRIORITY_BIT_OFFSET: int = 26: Bit offset of Priority parameter defined by SAE J1939.

DEFAULT_PRIORITY_VALUE: int = 6: Default value of Priority parameter defined by SAE J1939.

MIN_PRIORITY_VALUE: int = 0: Minimal value of Priority parameter defined by SAE J1939.

MAX_PRIORITY_VALUE: int = 7: Maximal value of Priority parameter defined by SAE J1939.

classmethod is_can_id(value)[source]

Check if the provided value is either Standard (11-bit) or Extended (29-bit) CAN ID.

Parameters:: value (int) – Value to check.
Returns:: True if value is a valid CAN ID, False otherwise.
Return type:: bool

classmethod is_standard_can_id(can_id)[source]

Check if the provided value is Standard (11-bit) CAN ID.

Parameters:: can_id (int) – Value to check.
Returns:: True if value is a valid 11-bit CAN ID, False otherwise.
Return type:: bool

classmethod is_extended_can_id(can_id)[source]

Check if the provided value is Extended (29-bit) CAN ID.

Parameters:: can_id (int) – Value to check.
Returns:: True if value is a valid 29-bit CAN ID, False otherwise.
Return type:: bool

classmethod validate_can_id(value, extended_can_id=None)[source]

Validate whether provided value is either Standard or Extended CAN ID.

Parameters:

value (int) – Value to validate.
extended_can_id (Optional[bool]) –
Flag whether to perform consistency check with CAN ID format.
- None - does not check the format of the value
- True - verify that the value uses Extended (29-bit) CAN ID format
- False - verify that the value uses Standard (11-bit) CAN ID format

Raises:

TypeError – Provided value is not int type.
ValueError – Provided value is out of CAN Identifier values range.

Return type:

None

classmethod validate_priority(value)[source]

Validate whether provided priority value is in line with SAE J1939 definition.

Parameters:

value (int) – Value to validate.

Raises:

TypeError – Provided value is not int type.
ValueError – Provided value is out of Priority values range.

Return type:

None

class uds.can.frame.CanDlcHandler[source]

Helper class that provides utilities for CAN Data Length Code field.

CAN Data Length Code (DLC) is a CAN frame field that informs about number of data bytes carried by CAN frames.

CAN DLC supports two values ranges:

0x0-0x8 - linear range which is supported by CLASSICAL CAN and CAN FD
0x9-0xF - discrete range which is supported by CAN FD only

__DLC_VALUES: Tuple[int, Ellipsis]

__DATA_BYTES_NUMBERS: Tuple[int, Ellipsis] = (0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 20, 24, 32, 48, 64)

__DLC_MAPPING: Dict[int, int]

__DATA_BYTES_NUMBER_MAPPING: Dict[int, int]

__DLC_SPECIFIC_FOR_CAN_FD: Set[int]

MIN_DATA_BYTES_NUMBER: int: Minimum number of data bytes in a CAN frame.

MAX_DATA_BYTES_NUMBER: int: Maximum number of data bytes in a CAN frame.

MIN_DLC_VALUE: int: Minimum value of DLC parameter.

MAX_DLC_VALUE: int: Maximum value of DLC parameter.

MIN_BASE_UDS_DLC: int = 8: Minimum CAN DLC value that can be used for UDS communication. Lower values of DLC are only allowed when CAN Frame Data Optimization is used.

classmethod decode_dlc(dlc)[source]

Map a value of CAN DLC into a number of data bytes.

Parameters:: dlc (int) – Value of CAN DLC.
Returns:: Number of data bytes in a CAN frame that is represented by provided DLC value.
Return type:: int

classmethod encode_dlc(data_bytes_number)[source]

Map a number of data bytes in a CAN frame into DLC value.

Parameters:: data_bytes_number (int) – Number of data bytes in a CAN frame.
Returns:: DLC value of a CAN frame that represents provided number of data bytes.
Return type:: int

classmethod get_min_dlc(data_bytes_number)[source]

Get a minimum value of CAN DLC that is required to carry the provided number of data bytes in a CAN frame.

Parameters:: data_bytes_number (int) – Number of data bytes in a CAN frame.
Returns:: Minimum CAN DLC value that is required to carry provided number of data bytes in a CAN frame.
Return type:: int

classmethod is_can_fd_specific_dlc(dlc)[source]

Check whether the provided DLC value is CAN FD specific.

Parameters:: dlc (int) – Value of DLC to check.
Returns:: True if provided DLC value is CAN FD specific, False otherwise.
Return type:: bool

classmethod validate_dlc(value)[source]

Validate whether the provided value is a valid value of CAN DLC.

Parameters:

value (int) – Value to validate.

Raises:

TypeError – Provided values is not int type.
ValueError – Provided value is not a valid DLC value.

Return type:

None

classmethod validate_data_bytes_number(value, exact_value=True)[source]

Validate whether the provided number of data bytes might be carried in a CAN frame.

Parameters:

value (int) – Value to validate.
exact_value (bool) –
Informs whether the value must be the exact number of data bytes in a CAN frame.
- True - provided value must be the exact number of data bytes to be carried by a CAN frame.
- False - provided value must be a number of data bytes that could be carried by a CAN frame (CAN Frame Data Padding is allowed).

Raises:

TypeError – Provided values is not int type.
ValueError – Provided value is not number of data bytes that matches the criteria.

Return type:

None