MATLAB: Unexpected MATLAB expression in app designer, using app designer in general

app designerMATLABmatlab guiserial

I wrote a code that compares a code coming in from a serial reader to a known set of codes. This is the code:
delete(instrfind('Port', 'COM3'));
tag = serial('COM3'); %check which port is used

fopen(tag);
%readData = fscanf(tag); %initialize

%writeData = uint16(500); % 0x01F4

%fwrite(tag, writeData, 'uint16') %write data

BOX = char(zeros(2,14)); 
i=1;
c=0;
TrueValueData = 'C:\Location_of_known_codes.xlsx';
[~,~,TrueValMat] = xlsread(TrueValueData); % Creates matrix filled with the correct values, 

                                           % indexed by box, which is the first row

                                           % all proceeding rows are the master values

for i=1:9223372036854775807
    if i>10 %first couple reads are filled with unicode nonsense, this skips that stage

    
     readData = fscanf(tag);
    if length(readData)>12
        
       BOX(str2num(readData(8)),1:14)= readData(11:24); % these numbers just give us what we want; 

                                                   % tags come in initially with some gobbledy-gook     

    end
%     
%      if(length(readData)>10) %if chip has been read
%          
%      ReadChips
    
   
          if strcmp(TrueValMat{2,1}, BOX(1,:))
             disp('hurray1')%set(handles.uipanel3, 'Backgroundcolor', 'g');
          else 
             disp('not hurray1') %set(handles.uipanel3, 'Backgroundcolor', 'r');
          end
        
            if strcmp(TrueValMat{2,2}, BOX(2,:))
             disp('hurray2') %set(handles.uipanel2, 'Backgroundcolor', 'g');
            else 
             disp('not hurray2') %set(handles.uipanel2, 'Backgroundcolor', 'r');
            end
    end
    
end
This code works as I want it to, much of the comments are leftovers from the code I initially found online. I want to turn this into a GUI, where instead of printing out 'hurray1' or 'not hurray1', it changes the color of a button in the GUI (as seen in the comments on line 31-41). Note that the above code does exactly what I want it to.
To this end, I used app designer, and played around until i came up with this code:
classdef GuiScanner_1 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure       matlab.ui.Figure
        GUITESTLabel   matlab.ui.control.Label
        READER1Button  matlab.ui.control.StateButton
        READER2Button  matlab.ui.control.StateButton
    end
delete(instrfindall); 
clear
clc
tag = serial('COM3'); %check which port is used
fopen(tag);
%readData = fscanf(tag); %initialize
%writeData = uint16(500); % 0x01F4
%fwrite(tag, writeData, 'uint16') %write data
BOX = char(zeros(2,14)); 
i=1;
c=0;
TrueValueData = 'C:\Location_of_known_codes.xlsx';
[~,~,TrueValMat] = xlsread(TrueValueData); % Creates matrix filled with the correct values, 
                                           % indexed by box, which is the first row
                                           % all proceeding rows are the master values
for i=1:9223372036854775807
    if i>10 %first couple reads are filled with unicode nonsense, this skips that stage
    
     readData = fscanf(tag);
    if length(readData)>12
        
       BOX(str2num(readData(8)),1:14)= readData(11:24); % these numbers just give us what we want; 
                                                   % tags come in initially with some gobbledy-gook     
    end
    methods (Access = private)
        % Value changed function: READER1Button
        function READER1ButtonValueChanged(app, event)
            value = app.READER1Button.Value;
              if strcmp(TrueValMat{2,1}, BOX(1,:))
             app.READER1Button.BackgroundColor = [0 1 0];
              else 
             app.READER1Button.BackgroundColor = [1 0 0];
              end
              
        end
        % Value changed function: READER2Button
        function READER2ButtonValueChanged(app, event)
            value = app.READER2Button.Value;
              if strcmp(TrueValMat{2,2}, BOX(2,:))
            app.READER2Button.BackgroundColor = [0 1 0];
            else 
            app.READER2Button.BackgroundColor = [1 0 0];
            end
        end
    end
    % App initialization and construction
    methods (Access = private)
        % Create UIFigure and components
        function createComponents(app)
            % Create UIFigure
            app.UIFigure = uifigure;
            app.UIFigure.Position = [100 100 640 480];
            app.UIFigure.Name = 'UI Figure';
            % Create GUITESTLabel
            app.GUITESTLabel = uilabel(app.UIFigure);
            app.GUITESTLabel.Position = [305 234 59 15];
            app.GUITESTLabel.Text = 'GUI TEST';
            % Create READER1Button
            app.READER1Button = uibutton(app.UIFigure, 'state');
            app.READER1Button.ValueChangedFcn = createCallbackFcn(app, @READER1ButtonValueChanged, true);
            app.READER1Button.Text = 'READER 1';
            app.READER1Button.BackgroundColor = [1 1 0];
            app.READER1Button.Position = [285 439 100 22];
            % Create READER2Button
            app.READER2Button = uibutton(app.UIFigure, 'state');
            app.READER2Button.ValueChangedFcn = createCallbackFcn(app, @READER2ButtonValueChanged, true);
            app.READER2Button.Text = 'READER 2';
            app.READER2Button.BackgroundColor = [1 1 0];
            app.READER2Button.Position = [285 24 100 22];
        end
    end
    methods (Access = public)
        % Construct app
        function app = GuiScanner_1
            % Create and configure components
            createComponents(app)
            % Register the app with App Designer
            registerApp(app, app.UIFigure)
            if nargout == 0
                clear app
            end
        end
        % Code that executes before app deletion
        function delete(app)
            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end
I have no idea if I even placed any of my code in the correct places at all. I keep getting an 'Unexpected MATLAB code' error on line 11, and I can't find what that means.
Another issue is that I want the color of the buttons to stay yellow, until something has actually been scanned, and not immediately turn red. I assume that would need a loop to keep the color yellow when BOX is still a matrix of only zeros. Again, I dont know whereor how to put that into th eGUI code.
Any help is much appreciated.

Best Answer

classdef GuiScanner_1 < matlab.apps.AppBase
    % Properties that correspond to app components
    properties (Access = public)
        UIFigure       matlab.ui.Figure
        GUITESTLabel   matlab.ui.control.Label
        READER1Button  matlab.ui.control.StateButton
        READER2Button  matlab.ui.control.StateButton
    end
delete(instrfindall); 
clear
clc
The line of code where you delete the objects returned by instrfindall is not inside any method of the class GuiScanner_1. Rather than copying your code into the class definition file, I would create a button or something else that when activated you want to run your code, and write a callback for that component in your app to call the script you've written. Why make a copy of the script in your app, which could get out of sync with your original script file as you fix bugs or add new features to one but not the other?
By the way, I would eliminate these lines from your script.
delete(instrfindall); 
clear
clc
clear eliminates all the variables in the workspace in which it's called. If this script gets called from a component's callback function that's more limited in scope, but you're still going to eliminate some of the useful variables the app passes into the callback by default. Usually it should be run interactively, at the MATLAB Command Prompt, when you've made a conscious decision that you want to clear the workspace.
clc is another tool with wide ranging effects. Again, I recommend using this interactively rather than in a script or function. Using it in an app (which a user likely would not expect to interact at all with the Command Window) is likely to lead to at least mild user confusion or annoyance.
delete(instrfindall) suggests to me that someone created an instrument object and forgot or chose not to delete that instrument object once they were finished. As this documentation page states "A good programming practice is to make sure that you leave your program environment in a clean state that does not interfere with any other program code." If what you're cleaning up is the object you created with:
tag = serial('COM3');
I would create an onCleanup to close and delete the serial object when the callback function that runs your script finishes its execution.
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