Property assignment is not allowed when the object is empty. Use subscripted assignment to create an array element.

This code is meant to read off a data stream from a creep frame and continuously save it until told to stop by attached ui. The problem is I had to move it to a new computer and reinstall everything necessary. Now I am getting a error from line 30 which states startBackground(s);

      Property assignment is not allowed when the object is empty.  Use subscripted assignment to create an array element.

here is the input code i used. a separate Ui is created where the controlling properties like time interval, radius, initial length, triaxality and displacement increment are told. along with a folder designated, and name of output file. What should happen is that once i press run, the program should start recording the data after file directory is selected. Instead as soon as file directory is selected I get the error.

here is the code

         clc;clear;

% c is a struct 
c.Date = clock;
c.Rate = 10;
%% Reading/Setting DAQ
s = daq.createSession('dt');

s.addAnalogInputChannel('DT9804(00)','0','Voltage');
s.addAnalogInputChannel('DT9804(00)','1','Voltage');
s.addAnalogInputChannel('DT9804(00)','2','Voltage');
s.addAnalogInputChannel('DT9804(00)','3','Voltage');
s.addAnalogInputChannel('DT9804(00)','4','Voltage');

s.Rate = c.Rate; % Background acuisition rate


%%
% Display graphical user interface
hGui = createDataCaptureUI(s);


% Add a listener for DataAvailable events and specify the callback function

dataListener = addlistener(s, 'DataAvailable', @(src,event) dataCapture(src, event, c, hGui));


% Start continuous background data acquisition
s.IsContinuous = true;
startBackground(s);


% Wait until session s is stopped from the UI
while s.IsRunning
    pause(0.5);
end

delete(dataListener);
delete(s);

I looked up solutions to the error online. but they do not seem to apply.

the gui file doesn't seem to be the source of the problem

[Rick Zrostlik]

I am getting the same error when trying to use my Data Translation 9847. However, I have ported my code from the 'Session' interface to the 'DataAcquisition' interface. My code:

>> daqlist
>> d =  daq('dt')
>> d.Rate = 30000
>> addinput(d,'DT9847-3-1(00)','0','Voltage')
>> data = read(d,30000);    %<--- this line causes the error for me

Answer 1

[per isakson]

Always include the full error message in the your question.

I don't have the data acquisition toolbox. However, the error messages says that

• there is an empty object
• a property assignment to that object failed
• a subscripted assignment will work

Example:

obj = ClassA.empty,  obj(1).t = 17      % subscripted assignment works

obj = 

  0×0 ClassA array with properties:

    t

obj = 
  ClassA with properties:

    t: 17

obj = ClassA.empty,  obj.t = 17         % fails

obj = 

  0×0 ClassA array with properties:

    t

Property assignment is not allowed when the object is empty. Use subscripted assignment to create an array element.

Now it remains to find out which object is empty and why.