Hello Xing,
The issue that you are facing is related to how MATLAB handles real-time data plotting within a loop, especially when using ‘fscanf’ to read data from a serial port and plotting each point individually. The ‘drawnow’ command, although necessary for updating plots in real-time, can significantly slow down execution when called repeatedly in a tight loop.
Here are some methods that you can apply to improve the time for the process:
1. Reduce the Frequency of Plot Updates
chunkSize = 100; % Adjust the chunk size as needed
while get(hObject, 'value')
if index <= 10000
output = fscanf(X,'%f');
T(index) = index;
Y(index) = output;
if mod(index, chunkSize) == 0 || index == 10000
plot(handles.Graph1, T(1:index), Y(1:index));
drawnow
end
index = index + 1;
end
end
Instead of plotting every single data point as it's read, consider plotting the data in chunks. This reduces the number of times the plot is refreshed.
2. Increase the Serial Buffer Size
MATLAB's serial port object has a property called ‘InputBufferSize’ that determines how much data it can hold in the buffer. Increasing this size can help MATLAB handle large bursts of data more efficiently. You can set this before opening the serial port connection.
3. Use read Instead of fscanf (MATLAB R2019a Onward)
If you are using MATLAB R2019a or newer, consider using the ‘read’ function for serial port objects created with ‘serialport’ instead of ‘fscanf’. The ‘read’ function can be more efficient and gives you more control over the number of bytes you read at a time.
You can also refer to this documentation from MathWorks about writing and reading Serial port data:
Hope it helps.
