尝试连接到打开COM端口时出错

Question

我正在尝试使用Matlab GUI连接到我的微控制器。第一步是设置元素，我的窗口包含4个轴，1个弹出窗口（选择com端口）和3个按钮，“connect”，“start”和“stop” 我需要用户选择COM端口，按下“connect”后将打开该端口。这是我的界面：

这是我的代码：

function varargout = gui2(varargin)
% GUI2 MATLAB code for gui2.fig
%      GUI2, by itself, creates a new GUI2 or raises the existing
%      singleton*.
%
%      H = GUI2 returns the handle to a new GUI2 or the handle to
%      the existing singleton*.
%
%      GUI2('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in GUI2.M with the given input arguments.
%
%      GUI2('Property','Value',...) creates a new GUI2 or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before gui2_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to gui2_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help gui2

% Last Modified by GUIDE v2.5 02-Mar-2017 15:10:00

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
    'gui_Singleton',  gui_Singleton, ...
    'gui_OpeningFcn', @gui2_OpeningFcn, ...
    'gui_OutputFcn',  @gui2_OutputFcn, ...
    'gui_LayoutFcn',  [] , ...
    'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT


% --- Executes just before gui2 is made visible.
function gui2_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to gui2 (see VARARGIN)

global comport ;
global COMnum ;


% Choose default command line output for gui2
handles.output = hObject;


% Update handles structure
guidata(hObject, handles);

% UIWAIT makes gui2 wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = gui2_OutputFcn(hObject, eventdata, handles)
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;


% --- Executes on button press in Connect1.
function Connect1_Callback(hObject, eventdata, handles)
% hObject    handle to Connect1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
COMnum = get(handles.COM2,'String');
comport = serial(COMnum, 'BaudRate', 115200); % setup comport
comport.InputBufferSize = 500000;
flushinput(comport);
fopen(comport);



% --- Executes on button press in Start1.
function Start1_Callback(hObject, eventdata, handles)
% hObject    handle to Start1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)


% --- Executes on button press in Stop1.
function Stop1_Callback(hObject, eventdata, handles)
% hObject    handle to Stop1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% --- Executes on selection change in COM2.
function COM2_Callback(hObject, eventdata, handles)
% hObject    handle to COM2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns COM2 contents as cell array
%        contents{get(hObject,'Value')} returns selected item from COM2
Com=get(handles.COM2,'string');
setappdata(0,'COM',Com);
guidata(hObject, handles);


% --- Executes during object creation, after setting all properties.
function COM2_CreateFcn(hObject, eventdata, handles)
% hObject    handle to COM2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

我的问题是，当我运行此程序时，我收到以下错误：

gui2


Error using serial (line 107)
Cannot create: No constructor with appropriate signature exists in Java class com.mathworks.toolbox.instrument.SerialComm

Error in gui2>Connect1_Callback (line 87)
comport = serial(COMnum, 'BaudRate', 115200); % setup comport

Error in gui_mainfcn (line 95)
        feval(varargin{:});

Error in gui2 (line 42)
    gui_mainfcn(gui_State, varargin{:});

Error in
matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)gui2('Connect1_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback

为什么会这样？

由于

Answer 1

查看uicontrol文档的示例部分，我们可以看到String（又名下拉列表）的'popup'属性包含单元格数组：

% Create pop-up menu
popup = uicontrol('Style', 'popup',...
       'String', {'parula','jet','hsv','hot','cool','gray'},...
       'Position', [20 340 100 50],...
       'Callback', @setmap);   

这就是为什么，当你打电话

时

COMnum = get(handles.COM2,'String');
comport = serial(COMnum, 'BaudRate', 115200); % setup comport

您正在为第一个参数传递serial个单元格数组，而期待字符串。

可以做些什么呢？文档也告诉我们：

  

Value属性存储当前所选列表框项的行索引

要使它起作用，你应该做类似的事情：

comport = serial(COMnum{get(handles.COM2,'Value')}, 'BaudRate', 115200);

我建议您调查一下 - 它包含有用的提示，可以帮助您自己找到问题。