"Attempt to reference field of non-structure array." when accessing a handle

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Ive written a GUI code which plots real time data from sensors With my GUI, i have a popup menu which lets the user select a value. In the function handle i store the chosen data into a handle "handles.numberofsensors".
The real time plotting is done by a timer function. I am able to access "handles.numberofsensors" from a push button callback function but I cant access "handles.numberofsensors" from the timerFcn of the timer object without the error.
Below are some excerpts from my code:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function popupmenu_Callback(hObject, eventdata, handles)
contents = cellstr(get(hObject,'String'));
handles.numberofsensors = contents{get(hObject,'Value')};
% stores popupmenu value into the handle
fprintf('Number of sensors to be use: %s\n', handles.numberofsensors);
guidata(hObject, handles); %update handles
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function start_button_Callback(hObject, eventdata, handles)
filename = 'C:\Program Files\xxxxxxxxxxxxxxxx';
d = get(handles.timer, 'UserData');
d.data = []; % array for the data to plot
d.data2 = [];
d.data3 = [];
% Figure/axis properties
axes(handles.axes1);
d.line_handle(1) = plot(NaN,NaN);
d.line_handle(2) = copyobj(d.line_handle(1),gca);
d.fid = fopen(filename, 'r');
set(handles.timer, 'UserData', d);
% Only START TIMER if it is not running
if strcmp(get(handles.timer, 'Running'), 'off')
start(handles.timer);
end
%ABLE TO ACCESS HANDLE HERE WITHOUT ERRORS
switch handles.numberofsensors
case '2'
fprintf('Producing real time plot for 2 sensors.\n');
case '4'
fprintf('Producing real time plot for 4 sensors.\n');
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%timerfcn%%%%%
function updateFigure(hObject, eventdata, handles)
% Timer timer1 callback, called each time timer iterates.
% Reads in new data from text file, appends data to correct format
% and plots/updates the values in the plot.
d = get(hObject, 'UserData');
% read new data from file
tmp = readFile(hObject);
% append to array in user data
d.data = [d.data transpose(tmp{1})];
d.data2 = [d.data2 transpose(tmp{2})];
d.data3 = [d.data3 transpose(tmp{3})];
%Plots data according to how many sensors are chosen
#ERRORS HERE. im unable to access handles.numberofsensors anywhere in this function
switch handles.numberofsensors
case '2'
set(d.line_handle, 'XData', d.data2, 'YData', d.data);
case '4'
set(d.line_handle, 'XData', d.data2, 'YData', d.data);
set(d.line_handle(2), 'XData', d.data2, 'YData', d.data3, 'color','r');
end
set(hObject, 'UserData', d);
Pretty much if i try access 'handles.numnberofsensors' anywhere in the timerFcn above, ill get the "Attempt to reference field of non-structure array." error.

回答(1 个)

Image Analyst
Image Analyst 2014-2-7
Are you sure you began your timer after you attached numberofsensors to handles, and not before?

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