function hPhotoMeter=ieInitializePhotoMeter(nCommPort);
% --- Helper function for initialize the PR650 photometer.

ieClearSerialPorts;

try
   hPhotoMeter = cmeter(nCommPort);
catch
   uiwait(errordlg('Error accessing the photometer, please check the
device...', 'Error', 'modal'));
   hPhotoMeter=[];
end;



function ieClearSerialPorts;
% --- Helper function for clearing all opened serial ports.
%See also: INSTRFIND. INSTRFIND Find serial port objects with specified
property values.

s=instrfind;
if ~isempty(s)
   fclose(s);
   delete(instrfind);
end;

Then use:

vSPD=getdata(hPhotoMeter, 'spectral');

or 

vXYZ=getdata(hPhotoMeter, 'xyz');

to get data.