DAQ output speed maximum

Question

Michael Leung 2011-9-15

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/15943-daq-output-speed-maximum

Hi,

I'm tring to use my NI card (PCI 6259) to output a "smooth" ramp function, similar to those you achieve from function generators.

function [] = Ramp(Vpp, Frequency, NumRepeat)
% Vpp = Voltage peak to peak
if isempty(NumRepeat)
    NumRepeat = 1;
end
x = 0.5 * Vpp * linspace(-1,1,500/Frequency)';
x = [x; -x];
ao_Ref = analogoutput('nidaq','Dev1');
addchannel(ao_Ref, 2);
set(ao_Ref,'SampleRate',1000);
% set(ao_Ref,'TriggerType','Immediate')
for j = 1:NumRepeat
    putdata(ao_Ref, x);
end
start(ao_Ref)

The code works fine. The only problem I am having is that the output voltage is given in tiny steps. The voltage is determining the position of an actuator, and thus the actuator does 1000 little "jumps" per second.

>> daqfind
Display Summary of Analog Output (AO) Object Using 'PCI-6259'.
       Output Parameters:  1000 samples per second on each channel.

The NI card should be able to output alot more then 1000 samples per second, if I am not mistaken. Is there a way to "smotthen" out the output voltage? (make it a linear slope, rather then 1000 small steps.

Any help would be appreciated.

Thanks,

Michael

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Michael Leung 2011-9-15

Is there a simpler way to achieve a ramp function??

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Answer 1

Walter Roberson 2011-9-15

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/15943-daq-output-speed-maximum#answer_21607

Ummm, you did set(ao_Ref,'SampleRate',1000) so why not try increasing that 1000 to a higher value?

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Walter Roberson 2011-9-15

For that card and single channel, the spec is 1.25 Msamp/second, so somewhere around 1250000 in theory. I don't know what the practical limit is (based upon MATLAB's overhead, the other operations happening on your system, and so on.)

Chirag Gupta 2011-9-15