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Generate and acquire signals with a DT9857E box using Matlab

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Hello,
i'm trying to generate and acquire signals for a study using a DT 9857E box, so i wrote a short code to test wether the result could be satisfying or not. The code is written this way:
clear all, clc, close all
s = daq("dt");
fAbtast = 50e3;
s.Rate = fAbtast; %1000;
BoxName = 'DT9857E-16(00)';
addoutput(s,BoxName, '0', 'Voltage');
addinput(s,BoxName,'0', 'Voltage');
fIn = 1e3;
t = 0:1/fAbtast:1-1/fAbtast;
x = sin(2*pi*fIn*t);
Output_data = x'*1.2;
Input_data = readwrite(s, Output_data);
figure
time_vec = seconds(Input_data.Time);
plot(time_vec, Output_data)
hold on
plot(time_vec, Input_data.Variables)
hold off
grid on
legend(["Output Signal","Acquired Signal"])
The result looks this way:
Any Idea on why the acquired signal does look that way? Since i just connected the output channel to the input channel, the same output signal or at least likely was expected to be acquired.
I even try to reproduce the example in the following matlab documentation: Simultaneously Acquire Data and Generate Signals - MATLAB & Simulink - MathWorks Deutschland
but the result did not look great:
%% Example from Matlab's documentation
% A session has been already defined
output = cos(linspace(0,2*pi,1000)');
data1 = readwrite(s, output);
figure
plot(output);
hold on
plot(data1.Variables);
ylabel("Voltage (V)")
%title("Acquired Signal");
legend(["Output Data","Acquired Signal"])
below is an enlarged view of the acquired signal
Any suggestion to fix this will be greatly appreciated.

Accepted Answer

Sulaymon Eshkabilov
Sulaymon Eshkabilov on 19 Feb 2024
It is all about DAQ
DT9857E issue.
Once we had also the same issue - a kind of exponential decay. So far, I remember what we did was to detrend the acquired data. Also, you can try to use a different channel of DT to collect data.
All the best.
  6 Comments
Galvani
Galvani on 24 Feb 2024
Further suggestions will be appreciated, my questions are still open :)
Thibaut
Thibaut on 17 May 2024 at 13:25
Hi!
I am facing the same issue here. Did you find a way to fix it? :)

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