serial data & real time plot

i want to get a serial data and plot its value against the time...

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

is it correct???

Answer 1

[Paulo Silva]

while 2>1 % infinite loop

you can do it better

 while 1 %same as while 2>1

Now for the plotting, first create a line (before the loop) with NaN values, liH=line(NaN,NaN) and inside the loop set the lines values.

set(liH,'XData',[get(liH,'XData') x]);
set(liH,'YData',[get(liH,'YData') a]);

If it gets too slow please consider the preallocation of XData and YData, fill it with NaN values and when the loop gets to the end of the preallocated data do something to "reset" it, if your script only runs for a short while you don't have to do it.

[Walter Roberson]

Myself I prefer

while true

[Paulo Silva]

while ~~~~~~~~~~~~~false