How can i break out of my while loop

Hi i have written a chunk of code, to send out 5v and 0v respectively from my labjack using Matlab and this is subject to the state of two switches either on or off. I put the code in a continuous while loop to keep monitoring the state of the switches, and to execute a command if any of the switches go high. But i want to be be able to breakout of the loop and display ( System error, can't detect sensors) if the while loop has run for 3mins, so the while loop doesn't just run forever. How can i achieve this. Below is my code

ljAsm = NET.addAssembly('C:\Program Files (x86)\LabJackU12Legacy\drivers\LJDotNet.dll');
idnum = -1;  %Using first found U12
demo = 0;  %Normal operations
errorString = NET.createArray('System.Char', 50); %Empty string for error message
disp(['Driver version: ', num2str(lj.LabJack.GetDriverVersion())]); %Display Labjack version
while 1 %Run continuous while loop
%Setting analog output
analogOut0 = 5.0;
analogOut1 = 5.0;
%Reading Reed switch from Digital Input IO0
channel = 0; %IO0
readD = 0; %Read IO line (>0 for D line)
state = 0; %Returned state (>0 = high, 0 = low)
[errorCode, idnum, state] = lj.LabJack.EDigitalIn(idnum, demo, channel, readD, state);
if state<0
  state=0
elseif state>0
  [errorCode, idnum] = lj.LabJack.EAnalogOut(idnum, demo, analogOut0, analogOut1);%Set both AO0 and AO1 to 5V
end
disp(['IO' num2str(channel) 'state' num2str(state)])%Display the state of Reed Switch connected to IO0
%Setting analog Output
analogOut0 = 0.0;
analogOut1 = 0.0;
%Reading Reed switch from Digital Input IO1
channel = 1; %IO0
readD = 0; %Read IO line (>0 for D line)
state = 0; %Returned state (>0 = high, 0 = low)
[errorCode, idnum, state] = lj.LabJack.EDigitalIn(idnum, demo, channel, readD, state);
if state<0
  state=0
elseif state>0
  [errorCode, idnum] = lj.LabJack.EAnalogOut(idnum, demo, analogOut0, analogOut1);%Set both AO0 and AO1 to 0V
end
disp(['IO' num2str(channel) 'state' num2str(state)])% Display the state of Reed Switch connected to IO1
end
pause(3.0)%Pause for three seconds before next scan

Answer 1

[Image Analyst]

Put this where you want to start timing:

tStart = tic;

Put this in the loop where you want to check how much time has elapsed, and break out of the loop if it has been more than 3 minutes:

tElapsed = toc(tStart); % Answer in seconds.
if tElapsed > 3*60 % 3 minutes
    break;
end

[Tochukwu]

Thanks for the reply but I wanted the loop to break only if the both switches IO0 and IO1 have a state of 0 for 3mins, this is so if the switches are not operated the loop can stop after 3mins to display ('System error switches not detected') thanks

[Image Analyst]

So set two timers going, each starts when the state goes to 0 for that variable. Then get the min elapsed time:

if sIO1 == 0 && io0 == 0
    tElapsed = toc(max(t1, t2));
end

[EDITED] to get the min elapsed time you need to get the max starting time, not the min like I had it.

[dpb]

OK, I'm bored this AM... :) Despite my previous comment here's another demo for OP of the two timer solution--

>> ts=tic;  % set the "go" time -- here I used the same start
   while 1
     t(1)=toc(ts); 
     pause(10*rand)
     t(2)=toc(ts);
     disp(t)
     if min(t)>15, break, end
  end
  0.0004    8.1488
  8.1498   17.2116
 17.2118   18.4929
>>

Answer 2

[dpb]

Try the following demonstration...

t3min=3/60/24;
tstop=now+t3min;
while now<tstop
  disp(datestr(clock))
  pause(15)
end

[Tochukwu]

Thanks for the reply but I wanted the loop to break only if the both switches IO0 and IO1 have a state of 0 for 3mins, this is so if the switches are not operated the loop can stop after 3mins to display ('System error switches not detected') thanks

[dpb]

...I wanted the loop to break only if the both switches IO0 and IO1 have a state of 0 for 3mins...

But you didn't say that, did you? :)

IA's two timer solution is about as clean as it gets. I could write the same thing in a different syntax, but no real point in it...