User`s manual

5 Calling Java from MATLAB
5-68
Example – Communicating Through a Serial Port
The serialexample program uses classes of the Java API javax.comm package,
which support access to communications ports. After defining port
configuration variables,
serialexample constructs a
javax.comm.CommPortIdentifier object, to manage the serial
communications port.
The program calls the open method on that object to
return an object of the
javax.comm.SerialPort class, which describes the
low-level interface to the
COM1 serial port, assumed to be connected to a
Tektronix oscilloscope. (The example can be run without an oscilloscope.) The
serialexample
program then calls several methods on the SerialPort object
to configure the serial port.
The
serialexample program uses the I/O package java.io, to write to and
read from the serial port. It calls a
static method to return an OutputStream
object for the serial port. It then passes that object to the constructor for
java.io.OutputStreamWriter. It calls the write method on the
OutputStreamWriter object to write a command to the serial port, which sets
the contrast on the oscilloscope. It calls
write again to write a command that
checks the contrast. It then constructs an object of the
java.io.InputStreamWriter class to read from the serial port.
It calls another
static method on the SerialPort object to return an
OutputStream object for the serial port. It calls a method on that object to get
the number of bytes to read from the port. It passes the InputStream object to
the constructor for
java.io.OutputStreamWriter. Then, if there is data to
read, it calls the
read method on the OutputStreamWriter object to read the
contrast data returned by the oscilloscope.
Note MATLAB also provides built-in serial port support, described in
Chapter 8, “Serial Port I/O”.