How to acquire and generate data using NI DAQ simultaneously on a continuous basis
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I have an NI input (9205) and NI output (9263) modules. I am trying to acquire and generate data in the same session but on a continuous basis. In this regard I referred to the tutorial provided for simultaneous acquisition and generation.
However when I try to do this on a continuous basis that is for an infinite amount of time I get the error : The data argument must contain one column for each output channel in the session.
I have pasted the code below.
function acquire_generate
clc;
global indata;
global outdata;
s3= daq.createSession('ni');
ch1= addAnalogInputChannel(s3,'cDAQ1Mod2','ai19','Voltage');
addAnalogOutputChannel(s3,'cDAQ1Mod7','ao0','Voltage');
ch1.InputType= 'SingleEnded';
s3.IsContinuous= true;
lh= s3.addlistener('DataAvailable',@plotData);% to plot acquire data in real time
s3.NotifyWhenDataAvailableExceeds=1000;
outdata= indata/2;
queueOutputData(s3,outdata);
lh1=s3.addlistener('DataRequired',@queueMoreData); % adding a listener to queue output data continuously
s3.startBackground();
while s3.IsRunning % to prevent Timeout
pause(0.5);
end
close(gcf);
figure(1);
plot(indata);
figure(2);
plot(outdata);
end
function plotData(src,event)
persistent localData;
global indata;
if(isempty(localData))
localData=[];
disp('acquiring starting');
end
plot(event.TimeStamps,event.Data);
localData= [localData;event.Data];
indata= localData;
if(max(event.Data)<5);
disp('Stopping acquire')
src.stop()
plot(event.TimeStamps,event.Data);
end
end
function queueMoreData(src,event)
global outdata;
queueOutputData(s3,outdata);
end
I am unable to figure out what I am doing wrong. Comments and insights will be appreciated. Thank you.
Regards,
Sri
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采纳的回答
Michael
2014-10-17
编辑:Michael
2014-10-17
I was having a different problem where I couldn't acquire for more than a few seconds.
for your problem, Srikrishnan, I'd start with the change below
ch(1) = addAnalogInputChannel(s3,'cDAQ1Mod2','ai19','Voltage');
ch(2) = addAnalogOutputChannel(s3,'cDAQ1Mod7','ao0','Voltage');
I was able to find that on Acquire Data and Generate Signals Simultaneously they say "When the session contains output channels, duration and number of scans become read-only properties of the session. The number of scans in a session is determined by the amount of data queued, and the duration is determined by s.ScansQueued/s.Rate.
Playing around with s.NotifyWhenDataAvailableExceeds fixed my problem.
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