How to save output from a timer that callback a function

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Ilaria Di Fresco 2016-10-12

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https://ww2.mathworks.cn/matlabcentral/answers/306974-how-to-save-output-from-a-timer-that-callback-a-function

评论： raym 2018-3-4

At the moment, I am working with a timer, which should run a function every half an hour. I am facing several troubles in saving the data generated by the function. The aim of my function (timerCallback) is to read some data from a website and record them into a vector called 'output'. Here is my function:

    function [output,b,vars]=timerCallback(obj,event,fullURL)
fullURL = ['http://realtimeweb-prod.nationalgrid.com/SystemData.aspx'];
str = urlread(fullURL);
expression = '<span id="ContentPlaceHolder1_lblScoEng">(.*)</span>MW';
[tokens,matches] = regexp(str,expression,'tokens','match');
p=str2double(tokens{1}{1});
c=clock;
output=[c(1:5),p];
set(obj,'UserData',output);
end

I'd like to callback this function each half an hour and record the new data in a matrix, in order to have an history of this data.

Here I define my timer:

t=timer('TimerFcn',{@timerCallback},...
          'ExecutionMode','fixedRate',...
          'TasksToExecute',Inf);

The timer works, the command

set(obj,'UserData',output);

works as well, so the UserData of the timer is updated every time.

What I am not able to do is to save this updated result in my Workspace (and then, as final step, to build the matrix with all the recorded data).

If I use the command:

get(obj,'UserData')

I am only able to get the latest data recorded. I think that I need to write a code able to repeat this command every time that the timer run the function.

Any suggestions are more than welcome.

Ilaria

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Ilaria Di Fresco 2016-10-14

在 MATLAB Online 中打开

Hi Mostafa,

Thanks a lot for your answer!

Unfortunately, I've just read it this morning and yesterday night I found a solution that fit my problem. I saved my output in a text file.

function [output]=timerCallback(obj,event,fullURL)
fullURL = ['http://realtimeweb-prod.nationalgrid.com/SystemData.aspx'];
str = urlread(fullURL);
expression = '<span id="ContentPlaceHolder1_lblScoEng">(.*)</span>MW';
[tokens,matches] = regexp(str,expression,'tokens','match');
p=str2double(tokens{1}{1});
c=clock;
output=[c(1:5),p];
fileID = fopen('Scotland-England.txt','at');
fprintf(fileID,'%d %d %d %d %d %d \n',output);
fclose(fileID);
end

Using 'at' (instead of 'w') I am able to write the new output without deleting the previous one.

Thanks

Ilaria

raym 2018-3-4

in the function ,first get(obj,'UserData'), then combine with the new output set(obj,'UserData',[get(obj,'UserData'),output]);

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How to save output from a timer that callback a function

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