i want to read the serial data using for loop... and want to get a real time data plot

function plot_Callback(hObject, eventdata, handles)
a1=0;

for i=1:1000

obj = serial('COM1');

set(obj,'BaudRate',9600)

fopen(obj); %open port

a = fscanf(obj); % read data into variable a

plot(a);

drawnow;

pause(0.5)

end

title('Axes 1');

xlabel('X data');

ylabel('Y data');

fclose(obj)

delete(obj);

clear obj;

will it work????... and do i need to create the object and set it for each run of for loop... and can u pls tell me what is the difference between com1 and com2?

[Jan]

Please cleanup your code. "a1" is not used. Omit everything, which does not cause troubles, e.g. title and labels. The readers will spend more time im helping you, if the loose less time in interpreting your code. Therefore a standard code formatting is recommended also: Start with two spaces, leave an empty line before the code.

Answer 1

[Jan]

COM1 is the first serial interface of your computer, COM2 is the second. Guess what COM3 is.

It is not clear , what you want to achieve. With some wild guessing I assume it will not work.

• Open the serial object once only before the loop.
• Does FSCANF work with serial objects in the shown way?
• Perhaps "plot(a)" would work, but it is not clear, if it does, what you want. Please describe any details.

obj = serial('COM1');
set(obj,'BaudRate',9600)
fopen(obj); %open port
for i=1:1000
   a = fscanf(obj); % ??? Does this work?
   plot(a);    % ??? Display the value of a at first
   pause(0.5);   % Calls DRAWNOW implicitely
end

[vishwash saxena]

i want to get the current signal as output from a sensor via serial communication and want to plot the value of current vs time.

that means like current= 4ma at time 3.45pm, current= 6.5 ma at time 3.55pm

[Jan]

I asked you to cleanup the posted code as comment to your question. I asked three questions here in this answer. I cannot see a reaction from your side. Therefore I assume the problem is not urgent. Good luck.

[vishwash saxena]

sorry jan ... i m not much familiar with matlab so was trying to figure it out...

here is the code ...

obj = serial('COM1') %creating the object

set(obj,'BaudRate',9600) %setting baudrate

fopen(obj); %open port

set(obj,'terminator','cr') %providing the terminator

a1=0; % a variable for y axis

time1=now; % time is in x axis

while 2>1 % infinite loop

time2=now;

x=[time1 time2];

ip_data = fscanf(obj) ;

a2= str2num(ip_data) ;

a=[a1 a2];

line(x,a);

datetick('x','HH:MM') %change the axis

pause(0.5);

a1=a2;

time1=time2;

end

now .. is it correct???

and can u pls tell me how fscanf was/is used in wrong way..

Answer 2

[Paulo Silva]

Here's a code that I made that plots the memory used by matlab in real time, I used some tips from the experts ;) adapt it to your needs.

   function test
  fig=figure;[user,sys] = memory;a=0;
  set(fig,'CloseRequestFcn','delete(gcf);')
  ax=axes;set(ax,'Ylimmode','manual');
  h = plot(ax,NaN, NaN,'LineWidth',5);
  set(ax,'Ylimmode','manual');
  set(ax,'YLim',[0 sys.PhysicalMemory.Total/10^6])
  ylabel('Memory used by matlab in Megabytes');
  t = timer('TimerFcn',@readdata,...
      'Period', 0.5,'executionmode','fixedSpacing');start(t)
      function readdata(g1,gg1)
          if (~ishandle(fig)),stop(t),return,end
          m=memory;mem=m.MemUsedMATLAB;
         set(h,'XData', [get(h, 'XData'), a],...
              'YData', [get(h, 'YData'), mem/10^6]);
          xd=get(h,'XData');yd=get(h,'YData');a=a+1;
          if numel(xd)>=100
              set(h,'XData',[xd(80:100)]);set(h,'YData',[yd(80:100)]);
          end
      end
  end

Answer 3

[vishwash saxena]

i want to get the current signal as output from a sensor via serial communication and want to plot the value of current vs time.

that means like current= 4ma at time 3.45pm, current= 6.5 ma at time 3.55pm Comment on this Answer

how can i achieve it?????

[Paulo Silva]

Here's one example that you can use and adapt, it reads the value of the memory used by matlab each second for 100 seconds and plots it, instead of your time values you can use just a number composed of hour minute second for each reading.

CData=[];

for a=1:100

c = clock; %[year month day hour minute seconds]

m=memory;

CData=[CData;m.MemUsedMATLAB/10^6 str2num(sprintf('%d%d%d',c(4),c(5),c(6)))]

pause(1)

end

%In the end you can plot the data

plot(CData(:,2),CData(:,1))

Answer 4

[vishwash saxena]

sorry jan ... i m not much familiar with matlab so was trying to figure it out...

here is the code ...

obj = serial('COM1')       %creating the object

set(obj,'BaudRate',9600)   %setting baudrate

fopen(obj); %open port

set(obj,'terminator','cr')  %providing the terminator

a1=0;     % a variable for y axis

time1=now;   % time is in x axis

while 2>1    % infinite loop

      time2=now;

      x=[time1 time2];

     ip_data = fscanf(obj) ;

      a2= str2num(ip_data) ;

      a=[a1 a2];

      line(x,a);

      datetick('x','HH:MM') %change the axis

      pause(0.5);

      a1=a2;

      time1=time2;

end

now .. is it correct???

and can u pls tell me how fscanf was/is used in wrong way..

[RITESH KUMAR]

How can i get continuous x data in excelsheet(csv file) in this program.

Answer 5

[Ankit Desai]

You might also want to consider using an event based read from serial port rather than a while or for loop.

If you are getting a datastream on the serial port you might want to take a look at the example I put on file exchange that shows event based read using a TCPIP object and plotting the read data. You can change the code to use a serial object.

If you are getting data after a query you might want to take a look at this example on file exchange that shows how to get data & plot using query based interactions.

Hope this helps,

-Ankit