DBC

The CAN bus database (DBC) functionality in Profinity provides tools for reading signals defined in DBC files that are loaded by the components in a profile. These files define the structure of CAN messages, including signals, message IDs, and data formats. A script does not load or parse a DBC file itself. The component that owns the DBC file loads it, and the script looks up that component's signals by name through Profinity.DBC. The DBC viewer shows the Component, Message, and Signal names that a script needs to track.

A script can do three things with a component's loaded DBC file:

Look up a signal definition by component, message, and signal name.
Read signal properties such as the unit, minimum, maximum, and comment.
Read the current physical value of a signal, converted from the latest raw CAN data using the signal's factor and offset.

The `GetDbcSignal` method

The GetDbcSignal method retrieves a signal definition from a component's loaded DBC file using the component name, message name and signal name.

Syntax

C#PythonLua

DbcSignal signal = Profinity.DBC.GetDbcSignal(string component, string message, string signal);

signal = Profinity.DBC.GetDbcSignal(component, message, signal)

local signal = Profinity.DBC:GetDbcSignal(component, message, signal)

Parameters

Parameter	Meaning
`component`	The name of the component in the profile that owns the DBC file
`message`	The name of the CAN message containing the signal
`signal`	The name of the signal to retrieve

Return value

Returns a DbcSignal object containing the signal definition. The method throws an ArgumentException when the component, message, or signal cannot be found. A script that could reference a missing name wraps the call in try/catch (C#), try/except (Python) or pcall (Lua).

Value property

The most important property of the returned DbcSignal object is Value, which returns the current physical value of the signal. Value is NaN (not a number) when no valid value is available. That happens when no packet has been received for the message yet, or when the last packet is older than the DBC validity period.

C#PythonLua

try
{
    // Get a signal definition
    var signal = Profinity.DBC.GetDbcSignal("ECU", "EngineData", "EngineSpeed");

    // Get the current physical value of the signal
    double currentValue = signal.Value;
    if (double.IsNaN(currentValue))
    {
        Profinity.Console.WriteLine("No valid value for EngineSpeed yet");
    }
    else
    {
        Profinity.Console.WriteLine($"Current engine speed: {currentValue} {signal.Unit}");
    }
}
catch (Exception ex)
{
    Profinity.Console.WriteLine($"Error reading DBC signal: {ex.Message}");
}

import math

try:
    # Get a signal definition
    signal = Profinity.DBC.GetDbcSignal("ECU", "EngineData", "EngineSpeed")

    # Get the current physical value of the signal
    current_value = signal.Value
    if math.isnan(current_value):
        print("No valid value for EngineSpeed yet")
    else:
        print(f"Current engine speed: {current_value} {signal.Unit}")
except Exception as ex:
    print(f"Error reading DBC signal: {ex}")

local ok, signal = pcall(function()
    return Profinity.DBC:GetDbcSignal('ECU', 'EngineData', 'EngineSpeed')
end)

if ok then
    local currentValue = signal.Value
    -- NaN is the only value that is not equal to itself
    if currentValue ~= currentValue then
        print('No valid value for EngineSpeed yet')
    else
        print('Current engine speed: ' .. tostring(currentValue) .. ' ' .. tostring(signal.Unit))
    end
else
    print('Error reading DBC signal: ' .. tostring(signal))
end

Names and conversion

GetDbcSignal throws an ArgumentException if any of the parameters do not match the profile or the DBC file. When the component is the one that does not match, the message is Component not found: followed by the name. The Value property converts the raw CAN data to the physical value using the signal's factor and offset. It returns NaN when the device is not valid or no current packet is available.

DBC

The GetDbcSignal method