(Not recommended) Write binary data to device
This serial object function is not recommended. Use serialport
object functions instead. See Compatibility Considerations.
fwrite(obj,A)
fwrite(obj,A,'precision')
fwrite(obj,A,'mode')
fwrite(obj,A,'precision','mode')
fwrite(obj,A) writes the binary
data A to the device connected to the serial port
object, obj.
fwrite(obj,A,'
writes binary data with precision specified by
precision')precision.
precision controls the number of bits written
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. The supported values for precision
are listed in Tips.
fwrite(obj,A,'
writes binary data with command-line access specified by
mode')mode. If
mode is sync,
A is written synchronously and the
command line is blocked. If mode is
async, A is written
asynchronously and the command line is not blocked. If
mode is not specified, the write
operation is synchronous.
fwrite(obj,A,'
writes binary data with precision specified by
precision','mode')precision and command-line access
specified by mode.
Before you can write data to the device, it must be connected to
obj with the
fopenStatus property value of
open. An error is returned if you attempt
to perform a write operation while obj is not
connected to the device.
The ValuesSent property value is increased by the
number of values written each time fwrite 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
OutputBufferSize property.
If you set the FlowControl (Instrument Control Toolbox)
property to hardware on a serial object, and a
hardware connection is not detected, fwrite
returns an error message. This occurs if a device is not connected, or
a connected device is not asserting that is ready to receive data.
Check the remote device status and flow control settings to see if
hardware flow control is causing errors in MATLAB®.
Note
If you want to check to see if the device is asserting that it
is ready to receive data, set the FlowControl (Instrument Control Toolbox) to
none. Once you connect to the device,
check the PinStatus structure for
ClearToSend. If
ClearToSend is
off, there is a problem on the
remote device side. If ClearToSend is
on, there is a hardware
FlowControl (Instrument Control Toolbox) device prepared to receive
data and you can execute fwrite.
By default, data 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:
The BytesToOutput
property value is continuously updated to reflect
the number of bytes in the output buffer.
The callback function specified for the
OutputEmptyFcn property is
executed when the output buffer is empty.
You can determine whether an asynchronous write operation is in
progress with the TransferStatus
property.
A binary write operation using fwrite
completes when:
The specified data is written.
The time specified by the
Timeout property
passes.
Note
The Terminator property
is not used with binary write operations.
The following table shows the supported values for
precision.
Data Type | Precision | Interpretation |
|---|---|---|
Character |
| 8-bit unsigned character |
| 8-bit signed character | |
| 8-bit signed or unsigned character | |
Integer |
| 8-bit integer |
| 16-bit integer | |
| 32-bit integer | |
| 8-bit unsigned integer | |
| 16-bit unsigned integer | |
| 32-bit unsigned integer | |
| 16-bit integer | |
| 32-bit integer | |
| 32- or 64-bit integer | |
| 16-bit unsigned integer | |
| 32-bit unsigned integer | |
| 32- or 64-bit unsigned integer | |
Floating-point |
| 32-bit floating point |
| 32-bit floating point | |
| 32-bit floating point | |
| 64-bit floating point | |
| 64-bit floating point |