Diagnostic Configuration

The Diagnostic Configuration module provides a mechanism for describing the conditions under which an ECU supports diagnostic messages. It allows applications to model ECU operating states and define the availability of diagnostic functions depending on the current state.

The implementation is located in the uds.diagnostic_configuration package and consists of the following components:

State
States Definitions
ECU Diagnostic Configuration

State

The State class represents a single ECU state that may affect the availability of diagnostic functions. A state has a name, a predefined set of allowed values, and a current value representing the ECU’s current operating condition.

Attributes:

name - name of a state
possible_values - collection of all values the state can assume
current_value - current value of the state

Example code:

import uds

# create an example state describing the active diagnostic session
session = uds.diagnostic_configuration.State(name="Diagnostic Session",
                                             possible_values={"Default", "Programming", "Extended"})

# change the current session
session.current_value = "Default"

# mark the current session as undefined
session.current_value = None

States Definitions

The uds.diagnostic_configuration.state_definitions module provides predefined State objects representing the most common ECU states used in UDS diagnostic communication. These definitions can be used directly or serve as a starting point for creating custom diagnostic configurations.

The following state definitions are provided:

DEFAULT_DIAGNOSTIC_SESSION_STATE - current diagnostic session
DEFAULT_SECURITY_ACCESS_STATE - currently unlocked security access level
DEFAULT_AUTHENTICATION_STATE - current authentication state
DEFAULT_IGNITION_STATE - current ignition status
DEFAULT_ENGINE_STATE - current engine state
DEFAULT_SECURED_TRANSMISSION_STATE – indicates whether secured data transmission is active
DEFAULT_ADDRESSING_TYPE_STATE – current addressing type (physical or functional)

ECU Diagnostic Configuration

The EcuDiagnosticConfiguration class is the central component of the Diagnostic Configuration module. It stores the ECU states relevant for diagnostic communication together with the restrictions that determine when diagnostic services, sub-functions, DID and RID are available.

Restrictions can be defined at multiple levels of specificity:

Service Identifier (SID)
Sub-function (for a given SID)
Data Identifier (DID, for a given SID)
Routine Identifier (RID, for a given SID)

More specific restrictions complement or override the restrictions defined at higher levels.

Attributes:

states - configured ECU states
states_names - names of all configured states
states_mapping - mapping from state name to State object
sid_restrictions - restrictions defined for diagnostic services (SIDs)
subfunction_restrictions - restrictions defined for service sub-functions
did_restrictions - restrictions defined for Data Identifiers (DIDs)
rid_restrictions - restrictions defined for Routine Identifiers (RIDs)

Methods:

combine_restrictions() - combines multiple restriction definitions into a single effective restriction
get_restrictions() - returns the effective restrictions for a diagnostic message

Example code:

import uds

# create an example (simplified) ECU Configuration
ecu_config = uds.diagnostic_configuration.EcuDiagnosticConfiguration(
    states=(uds.diagnostic_configuration.DEFAULT_DIAGNOSTIC_SESSION_STATE,
            uds.diagnostic_configuration.DEFAULT_SECURITY_ACCESS_STATE,
            uds.diagnostic_configuration.DEFAULT_ADDRESSING_TYPE_STATE),
    sid_restrictions={
        0x22: {
            "Session": {0x03},
            }},
    did_restrictions={
        0x22: {
            0xF190: {
                "Session": {0x03},
                "SecurityAccess": {0x01},
                "AddressingType": {uds.addressing.AddressingType.PHYSICAL}}
                }},
    rid_restrictions={},
    subfunction_restrictions={})

# Restrictions for ReadDataByIdentifier (0x22)
ecu_config.sid_restrictions[0x22]

# Restrictions for 22 (ReadDataByIdentifier) F1 90 (DID 0xF190) message
ecu_config.get_restrictions([0x22, 0xF1, 0x90])