概要
serial 创建一个串口对象，格式:s = serial('coml' )
fopen 打开串口对象，格式:fope n( s)
fread 读取串口数据，格式: fread(s)
fclose 关闭串口对象，格式:fclose(s)
free  解除Matlab对串口对象的控制，使
serial 其他程序能对该串口进行读写操作
delete 删除对象s，格式:delete( s)
clear 从工作空间中删除对象s，格式:clear(s)
fopen
Open file, or obtain information about open files
Syntax
fileID = fopen(filename)
fileID = fopen(filename, permission)
fileID = fopen(filename, permission, machineformat)
fileID = fopen(filename, permission, machineformat, encoding) [fileID, message] = fopen(filename, ...)
fIDs = fopen('all')
[filename, permission, machineformat, encoding] = fopen(fileID) Description
fileID = fopen(filename) opens the file filename for read access, and returns an integer file identifier.
fileID = fopen(filename, permission) opens the file with the specified permission.
fileID= fopen(filename, permission, machineformat) specifies the order for reading or writing bytes or bits in the file.
fileID= fopen(filename, permission, machineformat, encoding) specifies the character encoding scheme associated with the file.
[fileID, message] = fopen(filename, ...) opens a file. If the operation fails, message is a system-dependent error message. Otherwise, message is an empty string.
fIDs= fopen('all') returns a row vector containing the file identifiers of all open files.
[filename, permission, machineformat, encoding] = fopen(fileID) returns the file name, permission, machine format, and encoding that a previous call to fopen used when it opened the specified file. fopen does not read information from the file to determine these output values. An invalid fileID returns empty strings for all output arguments.
Input Arguments
filename String in single quotation marks that specifies the
name of the file to open. Can include a full or partial
path.
On UNIX systems, if filename begins with '~/' or
'~username/', the fopen function expands the path to
the current or specified user's home directory,
respectively.
If you open a file with read access and fopen cannot
find filename in the current folder, fopen searches
along the MATLAB search path. Otherwise, fopen
creates a file in the current directory.
permission String that describes the type of access for the file:
read, write, append, or update. Also specifies
whether to open files in binary or text mode.
To open files in binary mode, specify one of the
following:
'r' Open file for reading (default).
'w' Open or create new file for writing. Discard
existing contents, if any.
'a' Open or create new file for writing. Append data
to the end of the file.
'r+' Open file for reading and writing.
'w+' Open or create new file for reading and writing.
Discard existing contents, if any.
'a+' Open or create new file for reading and writing.
Append data to the end of the file.
'A' Append without automatic flushing. (Used with
tape drives.)
'W' Write without automatic flushing. (Used with
tape drives.)
To read and write to the same file:
∙Open the file in update mode (with a permission
that includes a plus sign, '+').
∙Call fseek or frewind between read and write
operations. For example, do not call fread
followed by fwrite, or fwrite followed by
fread, unless you call fseek or frewind between
them.
To open files in text mode, attach the letter 't' to
the permission, such as 'rt' or 'wt+'. For better
performance, do not use text mode. The following
applies on Windows systems, in text mode:
∙Read operations that encounter a carriage
return followed by a newline character ('\r\n')
remove the carriage return from the input.
∙Write operations insert a carriage return
before any newline character in the output.
This additional processing is unnecessary for most
cases. All MATLAB import functions, and most text
editors (including Microsoft Word and WordPad),
recognize both '\r\n' and '\n' as newline sequences.
However, when you create files for use in Microsoft
Notepad, end each line with '\r\n'. For an example,
see fprintf.
machineformat String that specifies the order for reading or writing
bytes or bits in the file. Specify machineformat to:
∙Read a file created on a different system.
∙Read bits in a particular order.
∙Create a file for use on a different system.
Possible values are:
'n' or 'native' The byte ordering that your system
uses (default)
'b' or 'ieee-be' Big-endian ordering
'l' or 'ieee-le' Little-endian ordering
's' or
'ieee-be.l64' Big-endian ordering, 64-bit data type
'a' or
'ieee-le.l64' Little-endian ordering, 64-bit data type
Windows systems use little-endian ordering, and most
UNIX systems use big-endian ordering, for both bytes
and bits.
encoding String that specifies the character encoding scheme
to use for subsequent read and write operations,
including fscanf, fprintf, fgetl, fgets, fread, and
fwrite.
Supported values are:
'Big5' 'ISO-8859-1' 'windows-932'
'EUC-JP' 'ISO-8859-2' 'windows-936'
'GBK' 'ISO-8859-3' 'windows-949'
'Macintosh' 'ISO-8859-4' 'windows-950'
'Shift_JIS' 'ISO-8859-9' 'windows-1250'
'US-ASCII' 'ISO-8859-13' 'windows-1251'
'UTF-8' 'ISO-8859-15' 'windows-1252'
'windows-1253'
'windows-1254'
'windows-1257'
For a list of additional encoding character sets, see
/assignments/character-sets. If
you specify a value for encoding that is not in the
list of supported values, MATLAB issues a warning.
Specifying other encodings sometimes (but not always)
fopen和open区别
produces correct results.
Default: system-dependent
Output Arguments
fileID An integer that identifies the file for all subsequent
low-level file I/O operations. If fopen cannot open
the file, fileID is -1.
MATLAB reserves file identifiers 0, 1, and 2 for
standard input, standard output (the screen), and
standard error, respectively. When fopen
successfully opens a file, it returns a file
identifier greater than or equal to 3.
message    A system-dependent error message when fopen cannot
open the specified file. Otherwise, an empty string.
fIDs Row vector containing the identifiers for all open
files, except the identifiers reserved for standard
input, output, and error. The number of elements in
the vector is equal to the number of open files. filename Name of the file associated with the specified fileID. permission The permission that fopen assigned to the file
specified by fileID.
machineformat The value of machineformat that fopen used when it
opened the file specified by fileID.
encoding The character encoding scheme that fopen associated
with the file specified by fileID.
The value that fopen returns for encoding is a
standard character encoding scheme name. It is not
always the same as the encoding argument that you used
in the call to fopen to open the file. Examples
Open a file. Pass the file identifier, fid, to other file I/O functions to read data and close the file.
fid = fopen('fgetl.m');

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