Is there a way to copy or extract or get the initial values or default Values of input ports of a bus or simulink Model with input signal names?

Hello All,

I am trying to extract or copy the initial Values or default values along with the input signal names of bus or simulink Model into a text file using matlab script.what is the Best way to extract the signal names and their defaul values?

Many Thanks in Advance!

Best Regards

JM

Answer 1

[Abhipsa]

Hi @Jaleel Mughal,

I understand that you want to automatically retrieve signal names from a Simulink model, get the initial or default values associated with the signals and write this information in a text file using MATLAB script.

This can be done using 2 approaches as shown below.

Approach 1

The below code snippet does the same for constant and sine block using “find_system” method in MATLAB and then iterating over the blocks:

% Define the model name
model = 'BusModel';  % Replace with your model name
load_system(model);

% Find all Bus Creator blocks
busCreators = find_system(model, 'BlockType', 'BusCreator');

% Open file to write output
fileID = fopen('signal_defaults.txt', 'w');
fprintf(fileID, 'Signal Name\tDefault Value\n');

for i = 1:length(busCreators)
    blk = busCreators{i};
    numInputs = str2double(get_param(blk, 'Inputs'));
    lines = get_param(blk, 'LineHandles');
    
    for j = 1:numInputs
        line = lines.Inport(j);
        if line ~= -1
            srcBlock = get_param(line, 'SrcBlockHandle');
            srcBlockName = get_param(srcBlock, 'Name');
            blockType = get_param(srcBlock, 'BlockType');
            
            defaultVal = 'N/A'; % Default

            if strcmp(blockType, 'Constant')
                defaultVal = get_param(srcBlock, 'Value');

            elseif strcmp(blockType, 'Sin')
                try
                    sineType = get_param(srcBlock, 'SineType');  % This exists for unmasked Sine blocks

                    if strcmp(sineType, 'Sample based')
                        % Get mask values
                        maskValues = get_param(srcBlock, 'MaskValues');
                        if length(maskValues) >= 4
                            amp = str2double(maskValues{1});
                            bias = str2double(maskValues{2});
                            samplesPerPeriod = str2double(maskValues{3});
                            offsetSamples = str2double(maskValues{4});

                            angle = 2 * pi * offsetSamples / samplesPerPeriod;
                            sineVal = amp * sin(angle) + bias;
                            defaultVal = num2str(sineVal);
                        end

                    elseif strcmp(sineType, 'Time based')
                        amp = str2double(get_param(srcBlock, 'Amplitude'));
                        bias = str2double(get_param(srcBlock, 'Bias'));
                        freq = str2double(get_param(srcBlock, 'Frequency'));
                        phase = str2double(get_param(srcBlock, 'Phase'));
                        t = 0;  % Evaluate at t = 0 as we need the default value

                        sineVal = amp * sin(freq * t + phase) + bias;
                        defaultVal = num2str(sineVal);
                    end
                catch
                    % Fallback: not a standard sine block
                    defaultVal = 'Error';
                end
            end

            fprintf(fileID, '%s\t%s\n', srcBlockName, defaultVal);
        end
    end
end

fclose(fileID);
disp('Signal names and default values saved to signal_defaults.txt');
close_system(model, 0);

You can customize the above code according to the blocks that you are using.

I have created the below model:

The script’s output for the above model:

Approach 2

Another way of achieving this by logging the signals and utilising “logsout” property of the model in the MATLAB script.

I am attaching a sample code demonstrating the same below:

% Define the model name
model = 'BusModel';  % Replace with your model name
load_system(model);

% Open file to write output
fileID = fopen('signal_defaults.txt', 'w');
fprintf(fileID, 'Signal Name\tDefault Value\n');
out = sim(model); % simulate the model
logsout = out.logsout;
numSignals = logsout.numElements
for i=1:numSignals
    srcSignalName = logsout{i}.Name; %this extracts the signal name, not the block name
    defaultVal = logsout{i}.Values.Data(1); %here idx 1 is extracted as we want the default value
    fprintf(fileID, '%s\t%s\n', srcSignalName, num2str(defaultVal));
end
fclose(fileID);
disp('Signal names and default values saved to signal_defaults.txt');
close_system(model, 0);

The below model is used for this approach :

Please note that the signals are logged here.

The output of this approach:

One advantage of approach 2 over the approach 1 is that there is no prior need of knowing the type of signal block used.

For more details you can refer to the below MATLAB documentations:

• Logging a signal: https://www.mathworks.com/help/releases/R2024b/simulink/ug/exporting-signal-data-using-signal-logging.html
• logsout property: https://www.mathworks.com/help/releases/R2024b/simulink/gui/signallogging.html
• find_system: https://www.mathworks.com/help/releases/R2024b/simulink/slref/find_system.html
• get_param: https://www.mathworks.com/help/releases/R2024b/simulink/slref/get_param.html
• sim: https://www.mathworks.com/help/releases/R2024b/simulink/slref/sim.html

I hope this resolves your query.