Generate and acquire signals with a DT9857E box using Matlab

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.

Answer 1

[Sulaymon Eshkabilov]

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.

[Galvani]

Thanks for the hint!

[Sulaymon Eshkabilov]

Welcome! Thumbs Up, please!

[Galvani]

The idea of detrending the acquired data or changing channel did not work. Since the shape of acquired signal is not the expected one, detrend does not help that much. I guess you may have done something else also to fix the issue :)

But again, thanks for your reply!

[Sulaymon Eshkabilov]

Most welcome! Glad to help!

[Galvani]

Further suggestions will be appreciated, my questions are still open :)