To read 3 channels of oscilloscope information on Matlab using TBS2000B, I have written the following .m file based on past forum posts
I am able to save the data to a csv file while drawing the graph.
https://forum.tek.com/viewtopic.php?t=139326#p282409
However, when I run the code, I often have problems with the oscilloscope screen freezing up or running too slowly anyway!
Also, there is a bug that the sine wave, which should be invisible on the screen, is somehow visible on the Matlab figure!
I think it is possible that the problem is stuck around the point where the information from Ch1~3 is put together and decomposed.
If there is a template for the matlab file to get the multi-channel information, I would appreciate it if you could let me know.
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clear all
close all
instrreset;
%% Preparation for Communication with Oscilloscope
visa_brand = 'ni';
visa_address = 'USB0::0x0699::0x03C7::C010948::INSTR';
% Open instrument with a default buffer size
osc = visa(visa_brand, visa_address);
fopen(osc);
% Get the current record length
record = str2double(query(osc, 'hor:reco?'));
% Close the instrument to set the buffer size
fclose(osc);
% Calculate required buffer size and set it
required_buffer = record * 2; % Adjust as needed
osc.InputBufferSize = required_buffer;
osc.OutputBufferSize = required_buffer;
% Reopen the instrument
fopen(osc);
% Create a folder to save data if it doesn't exist
if ~exist('data_all', 'dir')
mkdir('data_all');
end
% Set the file name
current_time = datetime('now', 'Format', 'yyyyMMdd_HHmmss');
csv_filename = sprintf('./data_all/%s.csv', current_time);
% Write the first row of the CSV file
titles = {'Timestamp', 'Voltage_CH1', 'Voltage_CH2', 'Voltage_CH3'};
fid = fopen(csv_filename, 'w');
fprintf(fid, '%s,%s,%s,%s\n', titles{:});
fclose(fid);
% Get scaling values
x_incr = str2double(query(osc, "wfmo:xincr?"));
x_zero = 0;
y_incr = str2double(query(osc, "wfmo:ymult?"));
y_off = str2double(query(osc, "wfmo:yoff?"));
y_zero = str2double(query(osc, "wfmo:yzero?"));
% Set DATA:SOURCE for CH1 and get scaling values
fwrite(osc, 'data:source CH1');
y_incr_ch1 = str2double(query(osc, "wfmo:ymult?"));
y_off_ch1 = str2double(query(osc, "wfmo:yoff?"));
% Set DATA:SOURCE for CH2 and get scaling values
fwrite(osc, 'data:source CH2');
y_incr_ch2 = str2double(query(osc, "wfmo:ymult?"));
y_off_ch2 = str2double(query(osc, "wfmo:yoff?"));
% Set DATA:SOURCE for CH3 and get scaling values
fwrite(osc, 'data:source CH3');
y_incr_ch3 = str2double(query(osc, "wfmo:ymult?"));
y_off_ch3 = str2double(query(osc, "wfmo:yoff?"));
% Set DATA:SOURCE for multiple channels
fwrite(osc, 'data:source CH1,CH2,CH3');
while(1)
tic
% Request sample data for all channels
fwrite(osc, 'curve?');
% Read binary block header
fread(osc, 1); % Discard '#' character
num_digits = char(fread(osc, 1)); % Number of digits that specify the number of bytes
num_digits = str2double(num_digits);
% Ensure num_digits is valid
if isnan(num_digits) || num_digits <= 0
warning('Invalid number of digits received from the oscilloscope.');
continue; % Skip this iteration
end
% Read the actual number of bytes
bytes = char(fread(osc, num_digits)');
num_bytes = str2double(bytes);
% Display for debugging purposes
fprintf('Number of bytes to read: %d\n', num_bytes);
% Check if num_bytes is a valid number
if isnan(num_bytes) || num_bytes <= 0
warning('Invalid number of bytes received from the oscilloscope.');
continue; % Skip this iteration
end
% Read digital values into sample matrix
all_samples = fread(osc, num_bytes, 'int8');
% Calculate the size of data for each channel
bytes_per_channel = floor(num_bytes / 3);
% Separate data for each channel
samples_ch1 = all_samples(1:bytes_per_channel);
samples_ch2 = all_samples(bytes_per_channel+1:2*bytes_per_channel);
samples_ch3 = all_samples(2*bytes_per_channel+1:end);
% Scale and transpose data for each channel with its own scaling
volt_ch1 = (samples_ch1 * y_incr_ch1) + y_off_ch1;
volt_ch1 = transpose(volt_ch1-mean(volt_ch1));
volt_ch2 = (samples_ch2 * y_incr_ch2) + y_off_ch2;
volt_ch2 = transpose(volt_ch2-mean(volt_ch2));
volt_ch3 = (samples_ch3 * y_incr_ch3) + y_off_ch3;
volt_ch3 = transpose(volt_ch3-mean(volt_ch3));
% Check and adjust the length of each channel's data
min_length = min([length(volt_ch1), length(volt_ch2), length(volt_ch3)]);
volt_ch1 = volt_ch1(1:min_length);
volt_ch2 = volt_ch2(1:min_length);
volt_ch3 = volt_ch3(1:min_length);
% Append time and save data
x_zero = 0;
x_range = record * x_incr;
x_max = x_range + x_zero;
% Adjust time array based on the minimum length
time = linspace(x_zero, x_max, record);
time = time(1:min_length); % Adjust the length of time array
temp_data = [time', volt_ch1', volt_ch2', volt_ch3'];
dlmwrite(csv_filename, temp_data, '-append', 'delimiter', ',');
temp_data = []; % Clear array
% Plotting the voltage data
plot(time, volt_ch1, time, volt_ch2, time, volt_ch3);
xlabel('Time (s)');
ylabel('Voltage (V)');
title('Oscilloscope Voltage Data');
grid on;
legend('CH1', 'CH2', 'CH3');
drawnow; % Update the plot in real time
toc
end
%% Close instrument
fclose(osc); % Close connection
delete(osc); % Remove the ICT object
clear osc; % Remove the local MATLAB variable
