USB 1608 DAQMI/MATLAB troubleshooting

[isherer]

We're seeing a different value in Matlab than we are in DAQami.

My versions:
Windows 10 

Instacal 6.60

Matlab 2024a

Data Acquisition Toolbox Support Package for Measurement Computing Hardware 24.1

We expect about 6 V and 0.5-0.9 Volts
DAQami is reading thosevalues correctly, but MATLAB when using slightly modified script of the example script at https://www.mathworks.com/help/daq/getting-started-with-session-based-interface-using-mcc-devices.html
we get these followings results where it starts at the correct values but then increases immediately to 10 V for both input channels. See attached graph.

%% Discover Available Devices
% Discover devices connected to your system using |daqlist|. To learn more
% about an individual device, access the entry in the device table.

d = daqlist("mcc");
d(1, :)

%% Create a DataAcquisition
% The |daq| function creates a DataAcquisition object. The DataAcquisition
% contains information describing hardware, scan rate, and other properties
% associated with the acquisition.

dq = daq("mcc")

%% Add an Analog Input Channel
% The |addinput| function attaches an input channel to the DataAcquisition.
% You can add more than one channel to a DataAcquisition.

addinput(dq, "Board0", "Ai5", "Voltage");
addinput(dq, "Board0", "Ai6", "Voltage");
dq

%% Change Default Properties of the Acquisition
% By default, acquisitions run for one second at 1000 scans per second.  To
% acquire at a different rate, change the |Rate| property.
dq.Rate = 100;

%%
% Run the acquisition and plot the acquired data:
[data, startTime] = read(dq, seconds(3));
hold on;
plot(data.Time, data.Board0_Ai5);
plot(data.Time, data.Board0_Ai6);
hold off;
xlabel("Time (s)"); 
ylabel("Voltage (V)");

 

[Fausto]

Hello @isherer.

Unlike DAQami, which allows a user to configure the input channels mode, the analog input channels should be configured for single-ended or differential mode in InstaCal before launching your MATLAB and wired accordingly.

What's the analog input channel mode in InstaCal and how are your sensors wired to the USB-1608G Series device?

Disconnect the other analog input channels or connect them to a ground screw terminal and then retest.

 

Regards,

Fausto

[isherer]

Hello @Fausto, 

 

The analog input mode is Single Ended, I configure this in instacal.

See attached pictures for wiring. I am using omega drc-4710 load cell signal conditioners attached to omega LCCA-50 load cells.

 

[isherer]

@Fausto

 

I disconnected everything and retested. I am still getting the same graph as above. What do you advise?

[Fausto]

Hello @isherer

Disconnect both load cells from the USB-1608G Series device. Wire the +5V terminal on the USB-1608G Series device to the CH5H and CH6H terminals. Run your MATLAB script. 
 

If the issue continues, wire the +5V terminal to CH0H and CH1H terminals instead and edit the channels in your script before retesting. Is the issue reproducible with these two channels?

Regards,

Fausto 

[isherer]

Hey @Fausto, 

 

I wired the +5V on the CH5H and CH6H to the same effect. I then wired the +5V to the CH0H and CH1H to the same effect as well. 

The attached png are the results of the CH0H and CH1H retest. 

 

DaqAmi has interesting results as well. In a single ended 1Hz reading, Channels 0 and 1 are correct with no voltage applied to CH5 and CH6. In a configuration of single ended and 1000 sample rates DaqAmi reads accurate values for CH0 and Ch1 and values close to CH0 and CH1 on channels 5 and 6. Please see attached excel sheets for recorded values.

SE1HzTest.xlsx SE1000HzTest.xlsx