Vehicle communication

Communication with ECUs in a vehicle can take place in several different ways, depending on the protocol used. This page lists examples of different ways in which such communication can take place. See the documentation page on vehicle communication for more information.

ISO-TP communication

The example below demonstrates how a VIN can be read from a vehicle using the ISO-TP protocol. This is done by configuring the required bus, specifying an ECU, and starting a stream to communicate with that ECU.

Python

from openobd import *


# Start an openOBD session on a ticket
openobd = OpenOBD()
openobd_session = openobd.start_session_on_ticket(TICKET_ID)    # The ticket ID needs to be filled in (as a string)

# Start the SessionTokenHandler to ensure the openOBD session remains authenticated
SessionTokenHandler(openobd_session)

# Define two buses with the ISO-TP protocol
print("Configuring buses...")
bus_configs = [
    (BusConfiguration(bus_name="bus_6_14",
                      can_bus=CanBus(pin_plus=6, pin_min=14, can_protocol=CanProtocol.CAN_PROTOCOL_ISOTP,
                                     can_bit_rate=CanBitRate.CAN_BIT_RATE_500,
                                     transceiver=TransceiverSpeed.TRANSCEIVER_SPEED_HIGH))),
    (BusConfiguration(bus_name="bus_3_11",
                      can_bus=CanBus(pin_plus=3, pin_min=11, can_protocol=CanProtocol.CAN_PROTOCOL_ISOTP,
                                     can_bit_rate=CanBitRate.CAN_BIT_RATE_500,
                                     transceiver=TransceiverSpeed.TRANSCEIVER_SPEED_HIGH)))
]
# Open a configureBuses stream, send the bus configurations, and close the stream
bus_config_stream = StreamHandler(openobd_session.configure_buses)
bus_config_stream.send_and_close(bus_configs)
print("Buses have been configured.")

# Define the engine control module, which is present on bus pins 6, 14, with CAN IDs 7E0-7E8, and turn on frame padding
ecm_channel = IsotpChannel(bus_name="bus_6_14", request_id=0x7E0, response_id=0x7E8, padding=Padding.PADDING_ENABLED)
# Start a stream to communicate with the engine
ecm = IsotpSocket(openobd_session, ecm_channel)

# Start an extended diagnostic session, with silent set to True so no ResponseException will be raised on an incorrect response
print("Sending 1003...")
response = ecm.request("1003", silent=True)
print(f"Response: {response}")

try:
    # Request the VIN from the engine, attempting it up to 2 times, each attempt waiting a maximum of 5 seconds for a response
    print("Sending 22F190...")
    response = ecm.request("22F190", tries=2, timeout=5)
    print(f"Response: {response}")

    # Decode and print the VIN, ignoring the first 3 bytes of the response
    vin = bytes.fromhex(response[6:]).decode("utf-8")
    print(f"VIN: {vin}")

# Catch any exceptions that are raised because of the ECU returning a negative response, or not responding at all
except ResponseException as e:
    print(f"Request failed: {e}")

finally:
    # Close the stream regardless of the result
    ecm.stop_stream()

# Close the session with a successful result
result = ServiceResult(result=[Result.RESULT_SUCCESS])
openobd_session.finish(result)