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MSO7104A: acquiring signals with ':DIGitize'

Question asked by fer_diablo_rojo on Oct 15, 2009
Latest reply on Oct 30, 2009 by dnt

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Hi! I'am trying to interface MSO7104A digital oscilloscope to my computer using
Matlab. Everything it's okay until i tried to acquire the data from any of the four analog channels.. I can't get the data..
this is my code.. i could read or modify everything in the scope. the only problem is acquiring the channels..

%% Create a VISA-USB object.
oscilo = instrfind('Type', 'visa-usb', 'RsrcName', 'USB0::2391::5973::MY48260590::0::INSTR', 'Tag', '');

% Create the VISA-USB object if it does not exist
% otherwise use the object that was found.
if isempty(oscilo)
    oscilo = visa('AGILENT', 'USB0::2391::5973::MY48260590::0::INSTR');
else
    fclose(oscilo);
    oscilo = oscilo(1)
end

%%

% Connect to instrument (me conecto al osciloscopio).
fopen(oscilo);
fprintf(oscilo,':AUToscale');

fprintf(oscilo,'TRIGger:SOURce CHANnel1');

    %mido amplitud canal 1
    fprintf(oscilo,':MEASure:SOURce CHANnel1');
    fprintf(oscilo,':MEASure:VRMS?');
    vrms= str2num(fscanf(oscilo));

    %Adquirir señales del canal 3

    fprintf(oscilo,':ACQuire:TYPE NORM');
    fprintf(oscilo,':ACQUIRE:COMPLETE 100');
    fprintf(oscilo,':DIGITIZE CHAN3');
    fprintf(oscilo,':MEASURE:SOURCE CHANNEL3');
    fprintf(oscilo,':MEASURE:FREQUENCY?');
    fre=str2num(fscanf(oscilo));


   fprintf(oscilo,':WAVEFORM:SOURCE CHAN1');
   fprintf(oscilo,':WAVEFORM:FORMAT WORD');
   fprintf(oscilo,':WAVEFORM:POINTS 1000');

fprintf(oscilo,':DIGitize CHAN1');

data = query(oscilo,':WAVEFORM:DATA?')

waveform_size=5000;

fprintf(oscilo,':WAVEFORM:PREAMBLE?');
pream=str2num(fscanf(oscilo));


fprintf(oscilo,':RUN');

fclose(oscilo);

Thanks!!!
Fernando.

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dnt Oct 15, 2009 4:07 PM

You set your waveform format to word, which is a binary format.
Does your 'query' know how to read a BINBLOCK format return?; because that is what you are going to get.
Try chaning the format to ASCII.

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fer_diablo_rojo Oct 16, 2009 1:53 PM

Thank you very much!! it worked!

Do you know if there is an easiest way to transfer data from an analog channel?.
What i mean is, is there a way to avoid having to read separate blocks of data then add them and then convert form string to number?

Thanks Again!
Fernando!

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fer_diablo_rojo Oct 19, 2009 3:04 PM

everything is okay until i tried to run this code several times:

%% Create a VISA-USB object.
oscilo = instrfind('Type', 'visa-usb', 'RsrcName', 'USB0::2391::5973::MY48260590::0::INSTR', 'Tag', '');

% Create the VISA-USB object if it does not exist
% otherwise use the object that was found.
if isempty(oscilo)
    oscilo = visa('AGILENT', 'USB0::2391::5973::MY48260590::0::INSTR');
else
    fclose(oscilo);
    oscilo = oscilo(1)
end

oscilo.InputBufferSize=13010;

oscilo.timeout=1000;

fopen(oscilo);
% Communicating with instrument object, obj1.

fprintf(oscilo,':WAVEFORM:SOURCE CHAN2');
fprintf(oscilo,':DIGitize CHAN2');
fprintf(oscilo, ':WAVEFORM:DATA?\n');
data_byte2= binblockread(oscilo,'int8');

fclose(oscilo)
plot(data_byte2)

If i run it once, i get what i want (the waveform in channel 2), but if i try to run the code several times i get this message:

Warning: A timeout occurred before the binblock was read. and i have to restart the oscilloscope to continue..

could you please help me??
thank you!!
Fernando

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dnt Oct 30, 2009 12:42 PM

Since this looks like MATLAB, my best guess is that the binblock read is leaving the newline in the scope's out buffer.
Try readuing one more character after the binblock read.

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4 Replies

dnt Oct 15, 2009 4:07 PM
Mark Correct
Correct Answer
You set your waveform format to word, which is a binary format.
Does your 'query' know how to read a BINBLOCK format return?; because that is what you are going to get.
Try chaning the format to ASCII.
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fer_diablo_rojo Oct 16, 2009 1:53 PM
Mark Correct
Correct Answer
Thank you very much!! it worked!

Do you know if there is an easiest way to transfer data from an analog channel?.
What i mean is, is there a way to avoid having to read separate blocks of data then add them and then convert form string to number?

Thanks Again!
Fernando!
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fer_diablo_rojo Oct 19, 2009 3:04 PM
Mark Correct
Correct Answer
everything is okay until i tried to run this code several times:

%% Create a VISA-USB object.
oscilo = instrfind('Type', 'visa-usb', 'RsrcName', 'USB0::2391::5973::MY48260590::0::INSTR', 'Tag', '');

% Create the VISA-USB object if it does not exist
% otherwise use the object that was found.
if isempty(oscilo)
    oscilo = visa('AGILENT', 'USB0::2391::5973::MY48260590::0::INSTR');
else
    fclose(oscilo);
    oscilo = oscilo(1)
end

oscilo.InputBufferSize=13010;

oscilo.timeout=1000;

fopen(oscilo);
% Communicating with instrument object, obj1.

fprintf(oscilo,':WAVEFORM:SOURCE CHAN2');
fprintf(oscilo,':DIGitize CHAN2');
fprintf(oscilo, ':WAVEFORM:DATA?\n');
data_byte2= binblockread(oscilo,'int8');

fclose(oscilo)
plot(data_byte2)

If i run it once, i get what i want (the waveform in channel 2), but if i try to run the code several times i get this message:

Warning: A timeout occurred before the binblock was read. and i have to restart the oscilloscope to continue..

could you please help me??
thank you!!
Fernando
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dnt Oct 30, 2009 12:42 PM
Mark Correct
Correct Answer
Since this looks like MATLAB, my best guess is that the binblock read is leaving the newline in the scope's out buffer.
Try readuing one more character after the binblock read.
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MSO7104A: acquiring signals with ':DIGitize'

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