Matlab instance variable not being saved, reverts to 0s - oop

Question

I am struggling to understand why my instance variables not being saved. Whenever I make a change to CurrentSettings, it does not appear next time I call another function. Basically it does not save and reverts to 0s after each function.
classdef laserControl
%LASERCONTROL This module is designed to control the laser unit.
% It can set the filter position, open and close the shutter and turn
% on/off the laser.
%
%%%%%%%%%%PORT LISTINGS%%%%%%%%%%%
%The set filter command is on port0
%The set shutter is in port1
%Laser 1 on port2
%Laser 2 on port3
%The filter digits are on ports 8-15 (the are on the second box)
properties%(GetAccess = 'public', SetAccess = 'private')
laserPorts; %The #'s of the output ports
currentSettings; %Current high/low settings
dio;
end
methods
%Constructor
%Opens the connection with the digital outputs
%Make sure to close the connection when finished
function Lobj = laserControl()
%Setup the laser
Lobj.laserPorts = [0:3 8:15];% 8:15
Lobj.currentSettings = zeros(1, length(Lobj.laserPorts));
%Make connection and reset values
Lobj.dio = digitalio('nidaq','Dev1');
addline(Lobj.dio, Lobj.laserPorts, 'out');
putvalue(Lobj.dio, Lobj.currentSettings);
end
%Closes the connection to the digital output
function obj = CloseConnection(obj)
putvalue(obj.dio, zeros(1, length(obj.currentSettings)));
delete(obj.dio);
clear obj.dio;
end
%Sets the position of the filter.
%positionValue - the integer amount for the position, cannot be
%larger than 150, as regulated by the box.
%The set filter command is on port0
%The filter digits are on ports 8-15 (the are on the second box)
function obj = SetFilterPosition(obj, positionValue)
if 0 <= positionValue && positionValue < 150
binaryDigit = de2bi(positionValue); %Convert it to binary form
%LaserOn OldSettings NewValue ExtraZeros
obj()
obj.currentSettings()
obj.currentSettings = [1 obj.currentSettings(1, 2:4) binaryDigit...
zeros(1, 8 - length(binaryDigit))];
putvalue(obj.dio, obj.currentSettings);
else
display('Error setting the filer: Value invalid');
end
end
end

Answer 1

Because your class does not inherit from handle, you've written a "value"-type class - in other words, when you make changes, you must capture the return value, like so:
myObj = SetFilterPosition( myObj, 7 );
For more on handle and value classes, see the doc