timer doesn't work
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hello everybody,with this timer I wonder why stops and don't carry on to execute. what's wrong? I want webread to be refreshed every 60 secs. tks
t = timer('TimerFcn', 'stat=false; disp(''Timer!'')',...
'StartDelay',60);
start(t)
stat=true;
while(stat==true)
webread('https://www..etc...');
pause(1)
end
采纳的回答
Benjamin Kraus
2023-2-21
编辑：Benjamin Kraus
2023-2-21
@Walter Roberson already pointed you to the documentation on how to Share Data Between Workspaces, which provides several ways to achieve your goal. I suggest reading that doc page.
function doStuff()
intervalInS=60;
everyNowAndThen = timer("Period",intervalInS,"ExecutionMode","fixedRate","TimerFcn",@refresh);
everyNowAndThen.start();
function refresh(~,~)
assignin('base','tbl',webread('https://api........CSV'))
end
end
The function webread('https://api........CSV') will be executed, and the result will be stored in the variable named tbl in the base workspace (i.e. workspace available at the command line).
Keep in mind that this means that as you are working, and as long as the timer is running, the variable tbl will continually be overwritten with the new data. Any other changes you make will be lost every time the timer executes.
Also keep in mind that if you are running other code when the timer is due to execute, your timer will wait until the other code is done. The reverse is also true, if your timer is running the webread command, no other MATLAB code will execute.
If your call to webread takes more than a fraction of a section, MATLAB will appear to hang every minute while webread is executing, which could be a pretty unplesant experience. I'm not sure if webread works with backgroundPool, but if you find yourself in this situation, you may want to look into backgroundPool to allow this code to run independently of your main MATLAB thread.
2 个评论
Walter Roberson
2023-2-21
timers potentially get control at the beginning of the each line of MATLAB code. But of course if you are doing a large vectorized operation or are calling a mex file it might be quite a while before the next matlab line is reached.
roberto
2023-2-22
更多回答（3 个）
Here it shows that it is working. An alternative way is to use [tic .. toc] to count time if this is the objective:
Tspan = 10; % Time span 10 seconds
t = timer('TimerFcn', 'stat=false; disp(''Timer!'')', 'StartDelay',Tspan);
start(t)
tic
stat=true;
while(stat==true)
webread('https://www.mathworks.com');
pause(1)
end
Tend = toc;
fprintf('Total time with [tic...toc]: %f \n', Tend)
Sulaymon Eshkabilov
2023-2-20
Here is how it can be attained:
Tspan = 240; % Time span 240 seconds
t = timer('TimerFcn', 'stat=false; disp(''Timer!'')', 'StartDelay', Tspan);
start(t)
Tupdated = 60;
tic
stat=true;
ii = 0;
while(stat==true)
ii=ii+1;
fprintf('WEB is read for %d time \n', ii);
DT={webread('https://www.mathworks.com')};
pause(Tupdated)
end
Tend = toc;
fprintf('Total time with [tic...toc]: %f \n', Tend)
12 个评论
Walter Roberson
2023-2-20
If you are going to run a timer, have the invoked function do the webread. Timer period 60, and you can set a TasksToExecute if you want a limited period.
roberto
2023-2-20
Walter Roberson
2023-2-20
URL = 'https://www.mathworks.com'; %adjust as appropriate
t = timer('TimerFcn', @(src,event)do_timer_stuff(src,event,URL), 'Period', 60, 'ExecutionMode', 'fixedspacing');
start(t)
function do_timer_stuff(src, event, URL)
DT = webread(URL);
%now do something with the data you read
end
roberto
2023-2-21
Walter Roberson
2023-2-21
Store the code in a file and execute the file.
roberto
2023-2-21
roberto
2023-2-21
Walter Roberson
2023-2-21
https://www.mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html
But remember you are configuring the timer to run indefinitely. You could store each result in a cell array, but your code is going to continue executing after you start() the timer. There is nothing that is sitting around waiting for new content to be added to the cell.
If what you want is to continually display the current content of the page then you should do that work inside the timer callback function.
Walter Roberson
2023-2-21
No there is not.
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