UDS OSI Model

Overview of UDS OSI model.

UDS Standards

UDS is defined by multiple standards which are the main source of information and requirements about this protocol. Full list of standards is included in the table below:

OSI Layer	Common	CAN	FlexRay	Ethernet	K-Line	LIN
Layer 7 Application	ISO 14229-1 ISO 27145-3	ISO 14229-3	ISO 14229-4	ISO 14229-5	ISO 14229-6	ISO 14229-7
Layer 6 Presentation	ISO 27145-2
Layer 5 Session	ISO 14229-2
Layer 4 Transport	ISO 27145-4	ISO 15765-2	ISO 10681-2	ISO 13400-2	Not applicable	ISO 17987-2
Layer 3 Network
Layer 2 Data		ISO 11898-1	ISO 17458-2	ISO 13400-3	ISO 14230-2	ISO 17987-3
Layer 1 Physical		ISO 11898-2 ISO 11898-3	ISO 17458-4		ISO 14230-1	ISO 17987-4

Where:

• OSI Layer - OSI Model Layer for which standards are relevant

• Common - standards mentioned in this column are always relevant for UDS communication regardless of bus used

• CAN - standards which are specific for UDS on CAN implementation

• FlexRay - standards which are specific for UDS on FlexRay implementation

• Ethernet - standards which are specific for UDS on IP implementation

• K-Line - standards which are specific for UDS on K-Line implementation

• LIN - standards which are specific for UDS on LIN implementation

UDS Functionalities

An overview of features that are required to fully implement UDS protocol is presented in the table below:

OSI Layer	Functionalities	Implementation
Layer 7 Application	diagnostic messages support	uds.message
Layer 6 Presentation	diagnostic messages data interpretation messaging database import from a file messaging database export to a file	To be provided with Database feature.
Layer 5 Session	Client simulation Server simulation	To be provided with Client feature. To be provided with Server feature.
Layer 4 Transport	UDS packet support bus specific segmentation bus specific packets transmission	uds.packet uds.segmentation uds.transport_interface uds.can To be extended with support for: Ethernet LIN K-Line FlexRay
Layer 3 Network
Layer 2 Data	frames transmission frames receiving	External python packages for bus handling: CAN: python-can More packages handling other buses to be decided.
Layer 1 Physical

Where:

• OSI Layer - considered OSI Model Layer

• Functionalities - functionalities required in the implementation to handle considered UDS OSI layer

• Implementation - UDS package implementation that provides mentioned functionalities

Protocol Data Units

Each layer of OSI Model defines their own Protocol Data Unit (PDU). To make things simpler for the users and our developers, in the implementation we distinguish following PDUs:

• Application Protocol Data Unit (A_PDU) - called diagnostic message or UDS Message in the implementation and documentation. More information about A_PDU can be found in:

  • knowledge base section - diagnostic message

  • implementation - diagnostic message

• Network Protocol Data Unit (N_PDU) - called UDS packet in the implementation and documentation. More information about N_PDU can be found in:

  • knowledge base section - UDS packet

  • implementation - uds.packet

• Data Protocol Data Unit (D_PDU) - called frame in the implementation and documentation. We do not have any internal frames documentation. Implementation of frames is usually provided by external packages.

UDS Protocol Data Units on different layers of OSI Model.