How to get real time plot of oscilloscope waveforms in matlab?

Question

Mohammad Zulqarnain 2016-12-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/316924-how-to-get-real-time-plot-of-oscilloscope-waveforms-in-matlab

I have connected a Keysight MSO-X 6004A oscilloscope to matlab through usb. I get waveform data from scope and it is displayed in matlab, meanwhile scope goes to stop mode. I am using the code given below:

%%Segmented Memory Averaging using MATLAB
% This example connects to an Agilent scope over TCPIP and sends SCPI
% commands to initiate a segmented mode acquisition and then
% averages the segments together before displaying the final, averaged 
% waveform in MATLAB
% 
% Note that this demos does not require drivers or any other layers in the
% software stack. It does however require connectng to an Agilent
% oscilloscope. The user can alternatively use the IPAddress "localhost" if
% MATLAB is installed directly on the oscilloscope.
%
% 
% Authors: Vinod Cherian, The MathWorks
%          Jeff Schuch, Agilent Technologies
%%Interface configuration and instrument connection
% Change the IP address to match your instrument's IP address
% Use 'localhost' if running from MATLAB installed directly on scope
%IPAddress = 'localhost';
%scopePort = 5025;
% Create a TCPIP object. Agilent instruments use port 5025 to send SCPI
% commands and receive data so use that information.
%tcpipObj = instrfind('Type', 'tcpip', 'RemoteHost', IPAddress, 'RemotePort', scopePort, 'Tag', '');
visaObj = visa('AGILENT', 'USB0::0x0957::0x1790::MY55190481::0::INSTR');
% Create the TCPIP object if it does not exist
% otherwise use the object that was found.
if isempty(visaObj)
    visaObj = tcpip(IPAddress, scopePort);
else
    fclose(visaObj);
    visaObj = visaObj(1);
end
% Set the buffer size. Change this buffer size to slightly over the number
% of bytes you get back in each read
visaObj.InputBufferSize = 350000;
% Set the timeout value
visaObj.Timeout = 1;
% Set the Byte order
visaObj.ByteOrder = 'littleEndian';
% Open the connection
fopen(visaObj)
%%Instrument Setup
% Now setup the instrument using SCPI commands. refer to the instrument
% programming manual for your instrument for the correct SCPI commands for
% your instrument.
% Set acquisition mode to segmented
fprintf(visaObj, ':ACQUIRE:MODE SEGMENTED');
% Set total number of points per segment
fprintf(visaObj, ':ACQUIRE:POINTS 40000');
% Set sample rate
fprintf(visaObj, ':ACQUIRE:SRATE 40e9');
% Turn interpolation off for faster averaging
fprintf(visaObj, ':ACQUIRE:INTERPOLATE OFF');
% Set total number of segments over which to average
fprintf(visaObj, ':ACQUIRE:SEGMENTED:COUNT 100');
% If needed, set the timebase
fprintf(visaObj, ':TIMEBASE:SCALE 100e-6');
% Force a trigger to capture segments
fprintf(visaObj,'*TRG');
% Depending on how many segments are captured, a  pause may be necessary in
% order to account for the time required to capture all of the segments
pause(2);
% Specify data from Channel 1
fprintf(visaObj,':WAVEFORM:SOURCE CHAN1'); 
% Get the data back as a BYTE (i.e., INT8)
fprintf(visaObj,':WAVEFORM:FORMAT BYTE');
% Set the byte order on the instrument as well
fprintf(visaObj,':WAVEFORM:BYTEORDER LSBFirst');
fprintf(visaObj, 'WAVEFORM:STREAMING OFF');
% Get the preamble block
preambleBlock = query(visaObj,':WAVEFORM:PREAMBLE?');
% The preamble block contains all of the current WAVEFORM settings.  
% It is returned in the form <preamble_block><NL> where <preamble_block> is:
%    FORMAT        : int16 - 0 = BYTE, 1 = WORD, 2 = ASCII.
%    TYPE          : int16 - 0 = NORMAL, 1 = PEAK DETECT, 2 = AVERAGE
%    POINTS        : int32 - number of data points transferred.
%    COUNT         : int32 - 1 and is always 1.
%    XINCREMENT    : float64 - time difference between data points.
%    XORIGIN       : float64 - always the first data point in memory.
%    XREFERENCE    : int32 - specifies the data point associated with
%                            x-origin.
%    YINCREMENT    : float32 - voltage diff between data points.
%    YORIGIN       : float32 - value is the voltage at center screen.
%    YREFERENCE    : int32 - specifies the data point where y-origin
%                            occurs.
%preambleBlock
% Maximum value storable in a INT8
maxVal = 2^8; 
%  split the preambleBlock into individual pieces of info
preambleBlock = regexp(preambleBlock,',','split');
% store all this information into a waveform structure for later use
waveform.Format = str2double(preambleBlock{1});     % This should be 0, since we're specifying INT8 output
waveform.Type = str2double(preambleBlock{2});
waveform.Points = str2double(preambleBlock{3});
waveform.Count = str2double(preambleBlock{4});      % This is always 1
waveform.XIncrement = str2double(preambleBlock{5}); % in seconds
waveform.XOrigin = str2double(preambleBlock{6});    % in seconds
waveform.XReference = str2double(preambleBlock{7});
waveform.YIncrement = str2double(preambleBlock{8}); % V
waveform.YOrigin = str2double(preambleBlock{9});
waveform.YReference = str2double(preambleBlock{10   });
waveform.VoltsPerDiv = (maxVal * waveform.YIncrement / 8);      % V
waveform.Offset = ((maxVal/2 - waveform.YReference) * waveform.YIncrement + waveform.YOrigin);         % V
waveform.SecPerDiv = waveform.Points * waveform.XIncrement/10 ; % seconds
waveform.Delay = ((waveform.Points/2 - waveform.XReference) * waveform.XIncrement + waveform.XOrigin); % seconds
%%Instrument control and data retreival
% Now control the instrument using SCPI commands. refer to the instrument
% programming manual for your instrument for the correct SCPI commands for
% your instrument.
% An optimization to try and speed up the data transfer
fclose(visaObj);
%visaObj.Terminator = '';
fopen(visaObj);
% Declare variables for use in processing the segments
N = 0;
Total_segments = 100;
Avg_N_segments = zeros(waveform.Points,1);
% This will loop through each of the captured segments and pull the data
% from each segment into MATLAB for processing
while (N<=Total_segments)
      % This will place the Nth segment on the screen so it can be pulled into
      % MATLAB for processing.
      fwrite(visaObj, sprintf(':ACQUIRE:SEGMENTED:INDEX %d\n',N));
      % Now send commmand to read data
      fwrite(visaObj,sprintf(':WAV:DATA?\n'));
      % Read back the BINBLOCK with the data in specified format and store it in
      % the waveform structure
      waveform.RawData = binblockread(visaObj);
      % Generate X & Y Data
      waveform.XData = (waveform.XIncrement.*(1:length(waveform.RawData))) - waveform.XIncrement;
      waveform.YData = (waveform.RawData - waveform.YReference) .* waveform.YIncrement + waveform.YOrigin;
      Measurement_Nth_Segment = waveform.YData;
      N = N + 1;
      % Average the current segment with the average of all the previously
      % captured segments
      if N>1
          Avg_N_segments = (((N-1) .* Avg_N_segments) + (Measurement_Nth_Segment)).*(1/N);
      else
          Avg_N_segments = Measurement_Nth_Segment;
      end
      %Uncomment next two lines to see average plotted as segments are processed
      plot(waveform.XData,Avg_N_segments); hold on;
      pause(0.01);
  end
%%Data Display and cleanup
% Plot the averaged data from all segments
plot(waveform.XData,Avg_N_segments)
set(gca,'XTick',(min(waveform.XData):waveform.SecPerDiv:max(waveform.XData)))
xlabel('Time (s)');
ylabel('Volts (V)');
title('Averaged Oscilloscope Data');
grid on;
% Close the TCPIP connection.
fclose(visaObj);
% Set the terminator back to LF
%visaObj.Terminator = 'LF';
% Delete objects and clear them.
delete(visaObj); clear visaObj;