Can you save all the values of the UserData field of a data acquisition session?

I'm acquiring data through a NiDaq device and have created a data acquisition session.

There are two fields that I created using the UserData (src.UserData.trip_type and src.UserData.trip_counter) .

I'm updating the values of these two fields when certain conditions are met (a voltage threshold) by one of the signals I'm acquiring.

This means that my UserData fields keep changing once those conditions are met, but I would like to constantly record their values, and get the timestamp of when their value changed. Is there a way to do that?

Thanks.

[Walter Roberson]

is there a reason why the code that changes the fields cannot do the recording of data?

[melanie basnak]

I'm not sure how to do that but if you can that would work! You can see my full function in the other comment.

Answer 1

[Aman Vyas]

Hi Melanie,

• Would it make sense to log the data and count it later?
• pre-calculate the zeros() and store them in a variable instead of having the zeros() inside the loop

You can use this:

mean(diff(acqData))

which is going to be identical to

(acqData(end) - acqData(1)) / (length(acqData) - 1)

You can look at "Acquire Timestamped data" section for more info in the following link:

https://www.mathworks.com/help/daq/examples/acquire-data-from-multiple-channels-using-mcc-devices.html?s_tid=answers_rc2-1_p4_Topic

Hope it helps!

[melanie basnak]

I'm not really following this, could you elaborate a bit more?

I think I also didn't explain the conditions of my acquisition properly.

I am acquiring several voltage signals. I want to use the signal in my 5th channel to change two variables, a trip counter and a trip type. The trip counter is important because once if reached a desired trip number, my acquisition needs to stop. I'm currently doing that with the following function:

function stopExp(src, event) 
%LEFT TRIP    
    %If this is an left trip and the animal has reached the end of the
    %hallway
     if (mode(event.Data(:,5)) > 4.9 && mode(event.Data(:,5)) < 7.5) && (strcmp(src.UserData.trip_type, 'left') == 1)
         % if she hasn't reached the total trip number
       if src.UserData.trip_counter < (src.UserData.trip_number - 1)
           src.UserData.trip_type = 'right'; %change the trip to right
           src.UserData.trip_counter = src.UserData.trip_counter + 1; %add 1 trip to the counter      
       %otherwise, if you've reached the desired trip number, stop panels and the experiment    
       else                   
            src.stop()           
       end  
       
%RIGHT TRIP       
       %If this is an right trip and the animal has reached the start of the
    %hallway
     elseif (mode(event.Data(:,5)) < 0.3) && (strcmp(src.UserData.trip_type, 'right') == 1)
       %if there have been less than the total trip number, keep going, change the
       %trip_type to left and add a trip to the trip_counter
       if src.UserData.trip_counter < (src.UserData.trip_number - 1)
            src.UserData.trip_type = 'left';
            src.UserData.trip_counter = src.UserData.trip_counter + 1;       
       %otherwise, if you've reached the total number of trips, stop the panels and the experiment    
       else                  
           src.stop()        
       end  
       
     else
              
     end
    
end

This function works, but at the end of the acquision, src.UserData.trip_type and src.UserData.trip_counter will only take the last values. I would like to save all the values they've taken and to know when in time they got updated.

[Aman Vyas]

Did you try "Acquire Timestamped" data that can read values at different different time stamps and thus finally you could plot those values.

 data = read(dq, seconds(1));

This read function starts the acquisition and returns the value as time table.

If it can be used for your problem.

Aman

[melanie basnak]

I don't have an MCC device, I have a NiDaq, and the read function is not working with that session.

[Aman Vyas]

For ni devices use the following documentation and refer to the "acquire data in the background" section. https://www.mathworks.com/help/daq/examples/log-analog-input-data-to-a-file-using-ni-devices.html

Also, you can take a look at this matlab answer which shares various techniques to do scontinuous and background acquisition. Link

Hope it helps !

[melanie basnak]

Oh but I am already doing that! I am acquiring my NiDaq data in the background, and I have a listener, which is calling that function I pasted up there. The variables that I want to store are not the voltage signals picked up by the NiDaq themselves, but rather these new variables I'm creating into the UserData of the session.