Hands-On: First UDS Communication

#!/usr/bin/env python3
# UDS Lab 01: Enter Extended Session + Read VIN (DID 0xF190)
import udsoncan
from udsoncan.connections import PythonIsoTpConnection
from udsoncan.client import Client
import isotp, can

# Setup: CAN interface (change 'vcan0' to your interface)
bus = can.Bus('vcan0', bustype='socketcan')
tp_addr = isotp.Address(isotp.AddressingMode.Normal_11bits,
                         rxid=0x7E8, txid=0x726)
stack = isotp.CanStack(bus=bus, address=tp_addr)
conn  = PythonIsoTpConnection(stack)

config = dict(udsoncan.configs.default_client_config)
config['request_timeout'] = 2  # seconds

with Client(conn, config=config) as client:
    # 1. Enter Extended Diagnostic Session
    resp = client.change_session(udsoncan.services.DiagnosticSessionControl.Session.extendedDiagnosticSession)
    print(f"Session: {'OK' if resp.positive else 'FAILED'}")

    # 2. Read VIN (DID 0xF190)
    resp = client.read_data_by_identifier(0xF190)
    if resp.positive:
        vin_bytes = resp.service_data.values[0xF190]
        print(f"VIN: {vin_bytes.decode('ascii', errors='replace')}")
    else:
        print(f"ReadDID failed: NRC 0x{resp.code:02X}")

    # 3. Read ECU Software Version (DID 0xF189)
    resp = client.read_data_by_identifier(0xF189)
    if resp.positive:
        sw_ver = resp.service_data.values[0xF189]
        print(f"SW Version: {sw_ver.hex()}")

#!/usr/bin/env python3
# Manually decode ISO 15765-2 multi-frame CAN trace
# Scenario: captured from CAN bus; DID 0xF190 VIN read

frames = [
    # Raw CAN frame bytes (8 bytes each)
    bytes.fromhex("101462F190574241"),  # FF: total=20, SID=0x62, DID=F190, data starts
    bytes.fromhex("3000000000000000"),  # FC from tester: BS=0, STmin=0
    bytes.fromhex("213132333435363738"),# CF seq=1
    bytes.fromhex("223930313233340000"),# CF seq=2 (last; 2 padding bytes)
]

def decode_cantp(frames):
    ff = frames[0]
    total_len = ((ff[0] & 0x0F) << 8) | ff[1]
    print(f"FF: total length = {total_len} bytes")
    payload = bytearray(ff[2:])  # 6 bytes from FF

    seq_expected = 1
    for f in frames[2:]:  # skip FC
        if (f[0] & 0xF0) == 0x20:  # CF
            seq = f[0] & 0x0F
            assert seq == seq_expected % 16, f"Sequence error: got {seq} expected {seq_expected}"
            payload.extend(f[1:])
            seq_expected += 1

    payload = bytes(payload[:total_len])
    print(f"Reassembled UDS payload ({len(payload)} bytes): {payload.hex()}")

    # Decode UDS response
    sid = payload[0]
    if sid == 0x62:  # positive response to 0x22
        did = (payload[1] << 8) | payload[2]
        data = payload[3:]
        print(f"ReadDataByIdentifier response: DID=0x{did:04X}")
        print(f"Data: {data.hex()} = {data.decode('ascii', errors='replace')}")

decode_cantp(frames)

#!/usr/bin/env python3
# Trigger a DTC, read it, then clear it
import udsoncan
from udsoncan.connections import PythonIsoTpConnection
from udsoncan.client import Client
import isotp, can

bus = can.Bus('vcan0', bustype='socketcan')
tp_addr = isotp.Address(isotp.AddressingMode.Normal_11bits, rxid=0x7E8, txid=0x726)
conn = PythonIsoTpConnection(isotp.CanStack(bus=bus, address=tp_addr))

with Client(conn, config=dict(udsoncan.configs.default_client_config)) as client:
    # Enter Extended Session
    client.change_session(udsoncan.services.DiagnosticSessionControl.Session.extendedDiagnosticSession)

    # Read all active DTCs (0x19 0x02 0xFF: all DTCs, any status)
    resp = client.get_dtc_by_status_mask(0xFF)
    if resp.positive:
        print(f"Active DTCs: {len(resp.service_data.dtcs)}")
        for dtc in resp.service_data.dtcs:
            print(f"  DTC: P{dtc.id:04X}  Status: 0x{dtc.status.byte:02X}")
    else:
        print("ReadDTC failed")

    # Clear all DTCs (0x14 0xFFFFFF)
    resp = client.clear_dtc(0xFFFFFF)  # group=0xFFFFFF = all DTCs
    print(f"ClearDTC: {'OK' if resp.positive else 'FAILED NRC 0x' + format(resp.code, '02X')}")

    # Re-read to confirm cleared
    resp = client.get_dtc_by_status_mask(0xFF)
    remaining = len(resp.service_data.dtcs) if resp.positive else -1
    print(f"DTCs after clear: {remaining} (expected: 0)")