|MATLAB Function Reference|
Write text to the device
||A serial port object.
||The string written to the device.
||C language conversion specification.
||Specifies whether data is written synchronously or asynchronously.
writes the string
cmd to the device connected to
obj. The default format is
%s\n. The write operation is synchronous and blocks the command line until execution is complete.
writes the string using the format specified by
format is a C language conversion specification. Conversion specifications involve the
% character and the conversion characters d, i, o, u, x, X, f, e, E, g, G, c, and s. Refer to the
sprintf file I/O format specifications or a C manual for more information.
writes the string with command line access specified by
cmd is written synchronously and the command line is blocked. If
cmd is written asynchronously and the command line is not blocked. If
mode is not specified, the write operation is synchronous.
writes the string using the specified format. If
cmd is written synchronously. If
cmd is written asynchronously.
Before you can write text to 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 write operation while
obj is not connected to the device.
ValuesSent property value is increased by the number of values written each time
fprintf is issued.
An error occurs if the output buffer cannot hold all the data to be written. You can specify the size of the output buffer with the
If you use the
help command to display help for
fprintf, then you need to supply the pathname shown below.
Synchronous Versus Asynchronous Write Operations
By default, text is written to the device synchronously and the command line is blocked until the operation completes. You can perform an asynchronous write by configuring the
mode input argument to be
async. For asynchronous writes:
BytesToOutputproperty value is continuously updated to reflect the number of bytes in the output buffer.
OutputEmptyFcnproperty is executed when the output buffer is empty.
You can determine whether an asynchronous write operation is in progress with the
Synchronous and asynchronous write operations are discussed in more detail in Controlling Access to the MATLAB Command Line.
Rules for Completing a Write Operation with fprintf
A synchronous or asynchronous write operation using
fprintf completes when:
Additionally, you can stop an asynchronous write operation with the
Rules for Writing the Terminator
All occurrences of
cmd are replaced with the
Terminator property value. Therefore, when using the default format
%s\n, all commands written to the device will end with this property value. The terminator required by your device will be described in its documentation.
Create the serial port object
s to a Tektronix TDS 210 oscilloscope, and write the
RS232? command with the
RS232? instructs the scope to return serial port communications settings.
Because the default format for
%s\n, the terminator specified by the
Terminator property was automatically written. However, in some cases you might want to suppress writing the terminator. To do so, you must explicitly specify a format for the data that does not include the terminator, or configure the terminator to empty.