Problem using start and getsnapshot

Hello,

I am trying to take pictures with a Basler Camera using a trigger sent by an Arduino card via the serial port (the camera and the arduino are connected to my laptop but are not connected together).

My code works sometimes, but most of the time it doesn't... I keep getting various error messages from my code, but I can't find the solution. I also have to unplug and plug again the arduino card everytime I want to run my code.

Here is an example of an error message I get:

Error using imaqdevice/start

Multiple image acquisition objects cannot access the same device simultaneously.

Error in testTriggerBasic (line 7)

start(vid);

Warning: Error updating Image.

Here is my code:

s=serialport('COM4', 9600);
vid=videoinput("gentl",1,"Mono8");
triggerconfig(vid,"immediate");        %I don't if this line is necessary%
start(vid);
stopprog=0;

while stopprog<100000                   %I did this just so that the loop would end and the last lines could be executed
    if s.NumBytesAvailable>0
        data=read(s,s.NumBytesAvailable, 'uint8');
        image=getsnapshot(vid);
        imshow(image)
    end
    stopprog=stopprog+1;
end

stop(vid);
delete(vid);
clear(vid);
clear(s);

Thank you for your help.

Answer 1

[Walter Roberson]

You have an existing videoinput active. For example you might have used control-C to stop acquisition, and so missed out on deleting the object.

The easiest approach is to exit MATLAB and restart it.

[Emilie]

Thank you for your answer, but even after restarting matlab and making sure the videoinput wasn't active, I still get the same error message... I managed to make it work once this morning but I have no idea how.