Prev: imline (R2007a) wait resume
Next: XOR 2 matrices with decimal values
From: Sean on 18 Jun 2008 17:43
Hello all And thanks ahead for your time,

I have a gui that is supposed to display input from a Nidaq
device in real time. I wish for it to do this as long as
the gui is up and running.

What I have now is a call in my main gui file opening
function to start the input:

main_OpeningFcn(hObject, eventdata, handles, varargin)

setappdata(0, 'fhupdate_feedback', @update_feedback);
analog_feedback()

%%%
Analog_feedback() then sets all of the trigger parameters
etc.:

%Stop running DAQ processes.
if(~isempty(daqfind))
stop(daqfind)
end

%Get analog input device and add channels.
ai = analoginput('nidaq', 'Dev1');
addchannel(ai, 0:1);

%Set trigger parameters.
set(ai, 'SampleRate', 2000);
set(ai, 'TriggerType', 'immediate');
set(ai, 'SamplesPerTrigger', 2000);
set(ai, 'TriggerRepeat', 0);

%Set timer parameters.
set(ai, 'TimerPeriod', .5);
set(ai, 'TimerFcn', {@daq_peek});
set(ai, {'StartFcn', 'StopFcn', 'TriggerFcn'}, {'','',''});


%Start acquiring data.
start(ai)
%%%%%%

%%%%%%%%
daq_peek(obj, event) %saves the data and transmits it back
to the main_gui

persistent data;
persistent load_cell;

size1 = min(floor((obj.SampleRate)*
(obj.Timerperiod)),obj.SamplesAvailable);
data = cat(1, data, peekdata(obj, size1));

load_cell = data(:,1);
displacement_1 = data(:, 2);

setappdata(0, 'displacement_1', displacement_1);
setappdata(0, 'load_cell', load_cell);

fhupdate_feedback = getappdata(0, 'fhupdate_feedback');
feval(fhupdate_feedback);

%%%%
I have the triggerepreat set at 0 so ideally this opening
function should get 2000 samples sent back to it and if I
set the repeat to inf it would run infinitely just as I
want.
However, it instead repeatedly runs to a number based on
the samplespertrigger (regardless of triggerrepeat setting).
With 2000 samples per trigger it runs to 16384 samples and
with 4000 samples per trigger it runs to 32768. It then
stops and when I attempt to close the gui it gives me
a "Warning object stopped before being deleted". This
makes sense because I never stopped ai. It then gives me a
fatal error of "could not find handle in my main gui" which
once again makes sense because the gui was deleted.

So what am I missing to make it run infinitely and how do I
stop it with the closerequest function to avoid the fatal
error?

Also, I'm running R2007b 7.5.0.

Thanks again,
-Sean
From: Sherryl Radbil on 19 Jun 2008 08:47
Hi Sean,

What do you mean by "It runs to 16384 samples"?
Where is this number coming from?
The fact that you're getting
"Warning object stopped before being deleted"
means that the AI object keeps running, so I would expect
that if you examine the AI's SamplesAvailable property over
time you'd see it continue to grow.

Out of curiosity, which device are you using?

I've adapted the code you posted as a small, non-GUI program
and ran with a simulated NI device and found that it runs
until I specifically stop it.

The code and a snippet of the result is below.
Try this code and if you still see it "stopping" there may
be an interaction with your GUI that must be considered.

Sherryl

ADAPTED CODE:

function dothis

%Stop running DAQ processes.
if(~isempty(daqfind))
stop(daqfind)
delete(daqfind) % It is important to delete unused
object to free resources
end

%Get analog input device and add channels.
ai = analoginput('nidaq', 'Dev1');
addchannel(ai, 0:1);

%Set trigger parameters.
set(ai, 'SampleRate', 2000);
set(ai, 'TriggerType', 'immediate');
set(ai, 'SamplesPerTrigger', 2000);
set(ai, 'TriggerRepeat', Inf);

%Set timer parameters.
set(ai, 'TimerPeriod', .5);
set(ai, 'TimerFcn', {@daq_peek});
set(ai, {'StartFcn', 'StopFcn', 'TriggerFcn'}, {'','',''});


%Start acquiring data.
start(ai)
%%%%%%

end

%%%%%%%%
function daq_peek(obj, event) %#ok<INUSD> %saves the data
and transmits it back to the main_gui

persistent data;
size1 = min(floor((obj.SampleRate)*
(obj.Timerperiod)),obj.SamplesAvailable);
data = cat(1, data, peekdata(obj, size1));
fprintf('%s %5d %d\n', datestr(now, 'HH:MM:SS.FFF'), size1,
obj.SamplesAvailable)

end

MY RESULTS:
08:41:53.385 1000 16384
08:41:53.885 1000 17408
08:41:54.385 1000 18432
08:41:54.885 1000 19456
08:41:55.385 1000 20480
08:41:55.885 1000 21504
08:41:56.385 1000 22528
08:41:56.885 1000 23552
08:41:57.385 1000 24576
08:41:57.885 1000 25600
>> stop(daqfind)

From: Sean on 19 Jun 2008 12:30
"Sherryl Radbil" <sherryl.radbil.dontspamme(a)mathworks.com>
> function dothis
>
> %Stop running DAQ processes.
> if(~isempty(daqfind))
> stop(daqfind)
> delete(daqfind) % It is important to delete unused
> object to free resources
> end
>
> %Get analog input device and add channels.
> ai = analoginput('nidaq', 'Dev1');
> addchannel(ai, 0:1);
>
> %Set trigger parameters.
> set(ai, 'SampleRate', 2000);
> set(ai, 'TriggerType', 'immediate');
> set(ai, 'SamplesPerTrigger', 2000);
> set(ai, 'TriggerRepeat', Inf);
>
> %Set timer parameters.
> set(ai, 'TimerPeriod', .5);
> set(ai, 'TimerFcn', {@daq_peek});
> set(ai, {'StartFcn', 'StopFcn', 'TriggerFcn'},
{'','',''});
>
>
> %Start acquiring data.
> start(ai)
> %%%%%%
>
> end

^^^^ ^^^^

Thanks a lot Sherryl!!
The problem was I was missing the end right there. Those
three letters absorbed about 8hrs of my life.
Thank you again.

 | 
Pages: 1
Prev: imline (R2007a) wait resume
Next: XOR 2 matrices with decimal values