External Interfaces Reference |
Read binary data from the device
Syntax
A = fread(obj,size)
A = fread(obj,size,'precision
')
[A,count] = fread(...)
[A,count,msg] = fread(...)
Arguments
Description
A = fread(obj,size)
reads binary data from the device connected to obj
, and returns the data to A.
The maximum number of values to read is specified by size
. Valid options for size
are:
n |
Read at most n values into a column vector. |
[m,n] |
Read at most m-by-n values filling an m-by-n matrix in column order. |
size
cannot be inf
, and an error is returned if the specified number of values cannot be stored in the input buffer. You specify the size, in bytes, of the input buffer with the InputBufferSize
property. A value is defined as a byte multiplied by the precision
(see below).
A = fread(obj,
reads binary data with precision specified by size
,'precision
')
precision
.
precision
controls the number of bits read for each value and the interpretation of those bits as integer, floating-point, or character values. If precision
is not specified, uchar
(an 8-bit unsigned character) is used. By default, numeric values are returned in double-precision arrays. The supported values for precision
are listed below in Remarks.
[A,count] = fread(...)
returns the number of values read to count
.
[A,count,msg] = fread(...)
returns a warning message to msg
if the read operation was unsuccessful.
Remarks
Before you can read data from the device, it must be connected to obj
with the fopen
function. A connected serial port object has a Status
property value of open
. An error is returned if you attempt to perform a read operation while obj
is not connected to the device.
If msg
is not included as an output argument and the read operation was not successful, then a warning message is returned to the command line.
The ValuesReceived
property value is increased by the number of values read, each time fread
is issued.
If you use the help
command to display help for fread
, then you need to supply the pathname shown below.
Rules for Completing a Binary Read Operation
A read operation with fread
blocks access to the MATLAB command line until:
Timeout
property passes.
Note
The Terminator property is not used for binary read operations.
|
Supported Precisions
The supported values for precision
are listed below.
Functions
Properties
BytesAvailable
, BytesAvailableFcn
, InputBufferSize
, Status
, Terminator
, ValuesReceived
fprintf (serial) | fscanf (serial) |
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