Basic Usage

This page explains the main components and core concepts of the library.

AT Commands

AT commands are special commands you send directly to the OBDII adapter. They let you configure it or retrieve information for/from the adapter.

main.py

from obdii import at_commands

# AT Command example, get the version ID of the adapter
at_commands.VERSION_ID

Commands

Commands are predefined instructions to request data from the vehicle, like engine speed, coolant temperature, DTC, etc. There are three equivalent ways of using commands.

main.py

from obdii import commands

# 1. Using a command directly
commands.ENGINE_SPEED

# 2. Using the command name
commands["ENGINE_SPEED"]

# 3. Using the Mode and PID
commands[0x01][0x0C]

# These three lines are equivalent
# and all return the same command object:
# <Command Mode.REQUEST 0C ENGINE_SPEED>

Scan for devices

Find your OBDII devices before you start. It could be connected via serial or WiFi. The obdii.utils.scan module makes this easy by scanning for available devices.

Note

Not sure which function to use ? Check Determining Your Port.

main.py

from obdii.utils.scan import scan_ports, scan_wifi

# Scan for devices connected via serial ports
ports = scan_ports()
print("Available OBDII devices:", ports)

# Scan for devices connected via WiFi
wifi_devices = scan_wifi()
print("Available OBDII WiFi devices:", wifi_devices)

Query data

To read real-time data, you need an obdii.Connection to the device. Once connected, you can send commands and get responses from your car.

main.py

from obdii import Connection, at_commands, commands
from obdii.utils.scan import scan_ports

# Find first available OBDII device connected via serial
ports = scan_ports(return_first=True)
if not ports:
    raise ValueError("No OBDII devices found.")

# Connect to the device and query engine speed
with Connection(ports[0]) as conn:
    version = conn.query(at_commands.VERSION_ID)
    print(f"Version: {version.value}")

    response = conn.query(commands.ENGINE_SPEED)
    print(f"Engine Speed: {response.value} {response.unit}")